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Add gstreamer-video docs
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Sebastian Dröge
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docs/gstreamer-video/docs.md
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docs/gstreamer-video/docs.md
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<!-- file * -->
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<!-- enum VideoColorMatrix -->
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The color matrix is used to convert between Y'PbPr and
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non-linear RGB (R'G'B')
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<!-- enum VideoColorMatrix::variant Unknown -->
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unknown matrix
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<!-- enum VideoColorMatrix::variant Rgb -->
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identity matrix
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<!-- enum VideoColorMatrix::variant Fcc -->
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FCC color matrix
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<!-- enum VideoColorMatrix::variant Bt709 -->
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ITU-R BT.709 color matrix
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<!-- enum VideoColorMatrix::variant Bt601 -->
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ITU-R BT.601 color matrix
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<!-- enum VideoColorMatrix::variant Smpte240m -->
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SMPTE 240M color matrix
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<!-- enum VideoColorMatrix::variant Bt2020 -->
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ITU-R BT.2020 color matrix. Since: 1.6.
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<!-- enum VideoColorPrimaries -->
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The color primaries define the how to transform linear RGB values to and from
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the CIE XYZ colorspace.
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<!-- enum VideoColorPrimaries::variant Unknown -->
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unknown color primaries
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<!-- enum VideoColorPrimaries::variant Bt709 -->
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BT709 primaries
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<!-- enum VideoColorPrimaries::variant Bt470m -->
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BT470M primaries
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<!-- enum VideoColorPrimaries::variant Bt470bg -->
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BT470BG primaries
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<!-- enum VideoColorPrimaries::variant Smpte170m -->
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SMPTE170M primaries
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<!-- enum VideoColorPrimaries::variant Smpte240m -->
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SMPTE240M primaries
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<!-- enum VideoColorPrimaries::variant Film -->
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Generic film
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<!-- enum VideoColorPrimaries::variant Bt2020 -->
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BT2020 primaries. Since: 1.6.
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<!-- enum VideoColorPrimaries::variant Adobergb -->
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Adobe RGB primaries. Since: 1.8
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<!-- enum VideoColorRange -->
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Possible color range values. These constants are defined for 8 bit color
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values and can be scaled for other bit depths.
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<!-- enum VideoColorRange::variant Unknown -->
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unknown range
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<!-- enum VideoColorRange::variant 0255 -->
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[0..255] for 8 bit components
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<!-- enum VideoColorRange::variant 16235 -->
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[16..235] for 8 bit components. Chroma has
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[16..240] range.
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<!-- struct VideoColorimetry -->
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Structure describing the color info.
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<!-- impl VideoColorimetry::fn from_string -->
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Parse the colorimetry string and update `self` with the parsed
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values.
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## `color`
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a colorimetry string
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# Returns
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`true` if `color` points to valid colorimetry info.
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<!-- impl VideoColorimetry::fn is_equal -->
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Compare the 2 colorimetry sets for equality
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## `other`
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another `VideoColorimetry`
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# Returns
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`true` if `self` and `other` are equal.
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<!-- impl VideoColorimetry::fn matches -->
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Check if the colorimetry information in `info` matches that of the
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string `color`.
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## `color`
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a colorimetry string
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# Returns
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`true` if `color` conveys the same colorimetry info as the color
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information in `info`.
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<!-- impl VideoColorimetry::fn to_string -->
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Make a string representation of `self`.
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# Returns
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a string representation of `self`.
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<!-- enum VideoFieldOrder -->
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Field order of interlaced content. This is only valid for
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interlace-mode=interleaved and not interlace-mode=mixed. In the case of
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mixed or GST_VIDEO_FIELD_ORDER_UNKOWN, the field order is signalled via
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buffer flags.
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<!-- enum VideoFieldOrder::variant Unknown -->
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unknown field order for interlaced content.
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The actual field order is signalled via buffer flags.
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<!-- enum VideoFieldOrder::variant TopFieldFirst -->
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top field is first
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<!-- enum VideoFieldOrder::variant BottomFieldFirst -->
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bottom field is first
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Feature: `v1_12`
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<!-- enum VideoFormat -->
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Enum value describing the most common video formats.
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<!-- enum VideoFormat::variant Unknown -->
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Unknown or unset video format id
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<!-- enum VideoFormat::variant Encoded -->
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Encoded video format. Only ever use that in caps for
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special video formats in combination with non-system
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memory GstCapsFeatures where it does not make sense
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to specify a real video format.
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<!-- enum VideoFormat::variant I420 -->
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planar 4:2:0 YUV
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<!-- enum VideoFormat::variant Yv12 -->
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planar 4:2:0 YVU (like I420 but UV planes swapped)
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<!-- enum VideoFormat::variant Yuy2 -->
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packed 4:2:2 YUV (Y0-U0-Y1-V0 Y2-U2-Y3-V2 Y4 ...)
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<!-- enum VideoFormat::variant Uyvy -->
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packed 4:2:2 YUV (U0-Y0-V0-Y1 U2-Y2-V2-Y3 U4 ...)
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<!-- enum VideoFormat::variant Ayuv -->
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packed 4:4:4 YUV with alpha channel (A0-Y0-U0-V0 ...)
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<!-- enum VideoFormat::variant Rgbx -->
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sparse rgb packed into 32 bit, space last
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<!-- enum VideoFormat::variant Bgrx -->
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sparse reverse rgb packed into 32 bit, space last
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<!-- enum VideoFormat::variant Xrgb -->
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sparse rgb packed into 32 bit, space first
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<!-- enum VideoFormat::variant Xbgr -->
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sparse reverse rgb packed into 32 bit, space first
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<!-- enum VideoFormat::variant Rgba -->
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rgb with alpha channel last
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<!-- enum VideoFormat::variant Bgra -->
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reverse rgb with alpha channel last
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<!-- enum VideoFormat::variant Argb -->
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rgb with alpha channel first
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<!-- enum VideoFormat::variant Abgr -->
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reverse rgb with alpha channel first
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<!-- enum VideoFormat::variant Rgb -->
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rgb
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<!-- enum VideoFormat::variant Bgr -->
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reverse rgb
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<!-- enum VideoFormat::variant Y41b -->
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planar 4:1:1 YUV
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<!-- enum VideoFormat::variant Y42b -->
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planar 4:2:2 YUV
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<!-- enum VideoFormat::variant Yvyu -->
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packed 4:2:2 YUV (Y0-V0-Y1-U0 Y2-V2-Y3-U2 Y4 ...)
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<!-- enum VideoFormat::variant Y444 -->
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planar 4:4:4 YUV
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<!-- enum VideoFormat::variant V210 -->
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packed 4:2:2 10-bit YUV, complex format
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<!-- enum VideoFormat::variant V216 -->
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packed 4:2:2 16-bit YUV, Y0-U0-Y1-V1 order
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<!-- enum VideoFormat::variant Nv12 -->
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planar 4:2:0 YUV with interleaved UV plane
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<!-- enum VideoFormat::variant Nv21 -->
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planar 4:2:0 YUV with interleaved VU plane
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<!-- enum VideoFormat::variant Gray8 -->
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8-bit grayscale
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<!-- enum VideoFormat::variant Gray16Be -->
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16-bit grayscale, most significant byte first
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<!-- enum VideoFormat::variant Gray16Le -->
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16-bit grayscale, least significant byte first
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<!-- enum VideoFormat::variant V308 -->
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packed 4:4:4 YUV (Y-U-V ...)
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<!-- enum VideoFormat::variant Rgb16 -->
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rgb 5-6-5 bits per component
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<!-- enum VideoFormat::variant Bgr16 -->
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reverse rgb 5-6-5 bits per component
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<!-- enum VideoFormat::variant Rgb15 -->
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rgb 5-5-5 bits per component
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<!-- enum VideoFormat::variant Bgr15 -->
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reverse rgb 5-5-5 bits per component
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<!-- enum VideoFormat::variant Uyvp -->
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packed 10-bit 4:2:2 YUV (U0-Y0-V0-Y1 U2-Y2-V2-Y3 U4 ...)
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<!-- enum VideoFormat::variant A420 -->
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planar 4:4:2:0 AYUV
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<!-- enum VideoFormat::variant Rgb8p -->
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8-bit paletted RGB
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<!-- enum VideoFormat::variant Yuv9 -->
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planar 4:1:0 YUV
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<!-- enum VideoFormat::variant Yvu9 -->
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planar 4:1:0 YUV (like YUV9 but UV planes swapped)
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<!-- enum VideoFormat::variant Iyu1 -->
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packed 4:1:1 YUV (Cb-Y0-Y1-Cr-Y2-Y3 ...)
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<!-- enum VideoFormat::variant Argb64 -->
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rgb with alpha channel first, 16 bits per channel
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<!-- enum VideoFormat::variant Ayuv64 -->
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packed 4:4:4 YUV with alpha channel, 16 bits per channel (A0-Y0-U0-V0 ...)
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<!-- enum VideoFormat::variant R210 -->
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packed 4:4:4 RGB, 10 bits per channel
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<!-- enum VideoFormat::variant I42010be -->
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planar 4:2:0 YUV, 10 bits per channel
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<!-- enum VideoFormat::variant I42010le -->
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planar 4:2:0 YUV, 10 bits per channel
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<!-- enum VideoFormat::variant I42210be -->
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planar 4:2:2 YUV, 10 bits per channel
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<!-- enum VideoFormat::variant I42210le -->
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planar 4:2:2 YUV, 10 bits per channel
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<!-- enum VideoFormat::variant Y44410be -->
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planar 4:4:4 YUV, 10 bits per channel (Since: 1.2)
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<!-- enum VideoFormat::variant Y44410le -->
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planar 4:4:4 YUV, 10 bits per channel (Since: 1.2)
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<!-- enum VideoFormat::variant Gbr -->
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planar 4:4:4 RGB, 8 bits per channel (Since: 1.2)
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<!-- enum VideoFormat::variant Gbr10be -->
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planar 4:4:4 RGB, 10 bits per channel (Since: 1.2)
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<!-- enum VideoFormat::variant Gbr10le -->
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planar 4:4:4 RGB, 10 bits per channel (Since: 1.2)
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<!-- enum VideoFormat::variant Nv16 -->
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planar 4:2:2 YUV with interleaved UV plane (Since: 1.2)
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<!-- enum VideoFormat::variant Nv24 -->
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planar 4:4:4 YUV with interleaved UV plane (Since: 1.2)
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<!-- enum VideoFormat::variant Nv1264z32 -->
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NV12 with 64x32 tiling in zigzag pattern (Since: 1.4)
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<!-- enum VideoFormat::variant A42010be -->
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planar 4:4:2:0 YUV, 10 bits per channel (Since: 1.6)
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<!-- enum VideoFormat::variant A42010le -->
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planar 4:4:2:0 YUV, 10 bits per channel (Since: 1.6)
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<!-- enum VideoFormat::variant A42210be -->
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planar 4:4:2:2 YUV, 10 bits per channel (Since: 1.6)
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<!-- enum VideoFormat::variant A42210le -->
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planar 4:4:2:2 YUV, 10 bits per channel (Since: 1.6)
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<!-- enum VideoFormat::variant A44410be -->
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planar 4:4:4:4 YUV, 10 bits per channel (Since: 1.6)
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<!-- enum VideoFormat::variant A44410le -->
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planar 4:4:4:4 YUV, 10 bits per channel (Since: 1.6)
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<!-- enum VideoFormat::variant Nv61 -->
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planar 4:2:2 YUV with interleaved VU plane (Since: 1.6)
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<!-- enum VideoFormat::variant P01010be -->
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planar 4:2:0 YUV with interleaved UV plane, 10 bits per channel (Since: 1.10)
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<!-- enum VideoFormat::variant P01010le -->
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planar 4:2:0 YUV with interleaved UV plane, 10 bits per channel (Since: 1.10)
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<!-- enum VideoFormat::variant Iyu2 -->
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packed 4:4:4 YUV (U-Y-V ...) (Since 1.10)
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<!-- enum VideoFormat::variant Vyuy -->
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packed 4:2:2 YUV (V0-Y0-U0-Y1 V2-Y2-U2-Y3 V4 ...)
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<!-- enum VideoFormat::variant Gbra -->
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planar 4:4:4:4 ARGB, 8 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Gbra10be -->
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planar 4:4:4:4 ARGB, 10 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Gbra10le -->
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planar 4:4:4:4 ARGB, 10 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Gbr12be -->
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planar 4:4:4 RGB, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Gbr12le -->
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planar 4:4:4 RGB, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Gbra12be -->
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planar 4:4:4:4 ARGB, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Gbra12le -->
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planar 4:4:4:4 ARGB, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant I42012be -->
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planar 4:2:0 YUV, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant I42012le -->
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planar 4:2:0 YUV, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant I42212be -->
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planar 4:2:2 YUV, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant I42212le -->
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planar 4:2:2 YUV, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Y44412be -->
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planar 4:4:4 YUV, 12 bits per channel (Since: 1.12)
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<!-- enum VideoFormat::variant Y44412le -->
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planar 4:4:4 YUV, 12 bits per channel (Since: 1.12)
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<!-- struct VideoFormatInfo -->
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Information for a video format.
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<!-- struct VideoFrame -->
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A video frame obtained from `VideoFrame::map`
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<!-- impl VideoFrame::fn copy -->
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Copy the contents from `src` to `self`.
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## `src`
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a `VideoFrame`
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# Returns
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TRUE if the contents could be copied.
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<!-- impl VideoFrame::fn copy_plane -->
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Copy the plane with index `plane` from `src` to `self`.
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## `src`
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a `VideoFrame`
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## `plane`
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a plane
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# Returns
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TRUE if the contents could be copied.
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<!-- impl VideoFrame::fn map -->
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Use `info` and `buffer` to fill in the values of `self`. `self` is usually
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allocated on the stack, and you will pass the address to the `VideoFrame`
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structure allocated on the stack; `VideoFrame::map` will then fill in
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the structures with the various video-specific information you need to access
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the pixels of the video buffer. You can then use accessor macros such as
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GST_VIDEO_FRAME_COMP_DATA(), GST_VIDEO_FRAME_PLANE_DATA(),
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GST_VIDEO_FRAME_COMP_STRIDE(), GST_VIDEO_FRAME_PLANE_STRIDE() etc.
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to get to the pixels.
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```C
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GstVideoFrame vframe;
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...
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// set RGB pixels to black one at a time
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if (gst_video_frame_map (&vframe, video_info, video_buffer, GST_MAP_WRITE)) {
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guint8 *pixels = GST_VIDEO_FRAME_PLANE_DATA (vframe, 0);
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guint stride = GST_VIDEO_FRAME_PLANE_STRIDE (vframe, 0);
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guint pixel_stride = GST_VIDEO_FRAME_COMP_PSTRIDE (vframe, 0);
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for (h = 0; h < height; ++h) {
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for (w = 0; w < width; ++w) {
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guint8 *pixel = pixels + h * stride + w * pixel_stride;
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memset (pixel, 0, pixel_stride);
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}
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}
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gst_video_frame_unmap (&vframe);
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}
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...
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```
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All video planes of `buffer` will be mapped and the pointers will be set in
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`self`->data.
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The purpose of this function is to make it easy for you to get to the video
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pixels in a generic way, without you having to worry too much about details
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such as whether the video data is allocated in one contiguous memory chunk
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or multiple memory chunks (e.g. one for each plane); or if custom strides
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and custom plane offsets are used or not (as signalled by GstVideoMeta on
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each buffer). This function will just fill the `VideoFrame` structure
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with the right values and if you use the accessor macros everything will
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just work and you can access the data easily. It also maps the underlying
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memory chunks for you.
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## `info`
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a `VideoInfo`
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## `buffer`
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the buffer to map
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## `flags`
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`gst::MapFlags`
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# Returns
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`true` on success.
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<!-- impl VideoFrame::fn map_id -->
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Use `info` and `buffer` to fill in the values of `self` with the video frame
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information of frame `id`.
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When `id` is -1, the default frame is mapped. When `id` != -1, this function
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will return `false` when there is no GstVideoMeta with that id.
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All video planes of `buffer` will be mapped and the pointers will be set in
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`self`->data.
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## `info`
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a `VideoInfo`
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## `buffer`
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the buffer to map
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## `id`
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the frame id to map
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## `flags`
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`gst::MapFlags`
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# Returns
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`true` on success.
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<!-- impl VideoFrame::fn unmap -->
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Unmap the memory previously mapped with gst_video_frame_map.
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<!-- struct VideoInfo -->
|
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Information describing image properties. This information can be filled
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in from GstCaps with `VideoInfo::from_caps`. The information is also used
|
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to store the specific video info when mapping a video frame with
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`VideoFrame::map`.
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Use the provided macros to access the info in this structure.
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<!-- impl VideoInfo::fn new -->
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Allocate a new `VideoInfo` that is also initialized with
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`VideoInfo::init`.
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# Returns
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a new `VideoInfo`. free with `VideoInfo::free`.
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<!-- impl VideoInfo::fn align -->
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Adjust the offset and stride fields in `self` so that the padding and
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stride alignment in `align` is respected.
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Extra padding will be added to the right side when stride alignment padding
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is required and `align` will be updated with the new padding values.
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## `align`
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alignment parameters
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# Returns
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`false` if alignment could not be applied, e.g. because the
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size of a frame can't be represented as a 32 bit integer (Since: 1.12)
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<!-- impl VideoInfo::fn convert -->
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Converts among various `gst::Format` types. This function handles
|
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GST_FORMAT_BYTES, GST_FORMAT_TIME, and GST_FORMAT_DEFAULT. For
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raw video, GST_FORMAT_DEFAULT corresponds to video frames. This
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function can be used to handle pad queries of the type GST_QUERY_CONVERT.
|
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## `src_format`
|
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`gst::Format` of the `src_value`
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## `src_value`
|
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value to convert
|
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## `dest_format`
|
||||
`gst::Format` of the `dest_value`
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## `dest_value`
|
||||
pointer to destination value
|
||||
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# Returns
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||||
|
||||
TRUE if the conversion was successful.
|
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<!-- impl VideoInfo::fn copy -->
|
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Copy a GstVideoInfo structure.
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# Returns
|
||||
|
||||
a new `VideoInfo`. free with gst_video_info_free.
|
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<!-- impl VideoInfo::fn free -->
|
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Free a GstVideoInfo structure previously allocated with `VideoInfo::new`
|
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or `VideoInfo::copy`.
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<!-- impl VideoInfo::fn from_caps -->
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Parse `caps` and update `self`.
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## `caps`
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||||
a `gst::Caps`
|
||||
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||||
# Returns
|
||||
|
||||
TRUE if `caps` could be parsed
|
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<!-- impl VideoInfo::fn init -->
|
||||
Initialize `self` with default values.
|
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<!-- impl VideoInfo::fn is_equal -->
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Compares two `VideoInfo` and returns whether they are equal or not
|
||||
## `other`
|
||||
a `VideoInfo`
|
||||
|
||||
# Returns
|
||||
|
||||
`true` if `self` and `other` are equal, else `false`.
|
||||
<!-- impl VideoInfo::fn set_format -->
|
||||
Set the default info for a video frame of `format` and `width` and `height`.
|
||||
|
||||
Note: This initializes `self` first, no values are preserved. This function
|
||||
does not set the offsets correctly for interlaced vertically
|
||||
subsampled formats.
|
||||
## `format`
|
||||
the format
|
||||
## `width`
|
||||
a width
|
||||
## `height`
|
||||
a height
|
||||
|
||||
# Returns
|
||||
|
||||
`false` if the returned video info is invalid, e.g. because the
|
||||
size of a frame can't be represented as a 32 bit integer (Since: 1.12)
|
||||
<!-- impl VideoInfo::fn to_caps -->
|
||||
Convert the values of `self` into a `gst::Caps`.
|
||||
|
||||
# Returns
|
||||
|
||||
a new `gst::Caps` containing the info of `self`.
|
||||
<!-- enum VideoInterlaceMode -->
|
||||
The possible values of the `VideoInterlaceMode` describing the interlace
|
||||
mode of the stream.
|
||||
<!-- enum VideoInterlaceMode::variant Progressive -->
|
||||
all frames are progressive
|
||||
<!-- enum VideoInterlaceMode::variant Interleaved -->
|
||||
2 fields are interleaved in one video
|
||||
frame. Extra buffer flags describe the field order.
|
||||
<!-- enum VideoInterlaceMode::variant Mixed -->
|
||||
frames contains both interlaced and
|
||||
progressive video, the buffer flags describe the frame and fields.
|
||||
<!-- enum VideoInterlaceMode::variant Fields -->
|
||||
2 fields are stored in one buffer, use the
|
||||
frame ID to get access to the required field. For multiview (the
|
||||
'views' property > 1) the fields of view N can be found at frame ID
|
||||
(N * 2) and (N * 2) + 1.
|
||||
Each field has only half the amount of lines as noted in the
|
||||
height property. This mode requires multiple GstVideoMeta metadata
|
||||
to describe the fields.
|
||||
<!-- enum VideoMultiviewMode -->
|
||||
All possible stereoscopic 3D and multiview representations.
|
||||
In conjunction with `VideoMultiviewFlags`, describes how
|
||||
multiview content is being transported in the stream.
|
||||
<!-- enum VideoMultiviewMode::variant None -->
|
||||
A special value indicating
|
||||
no multiview information. Used in GstVideoInfo and other places to
|
||||
indicate that no specific multiview handling has been requested or
|
||||
provided. This value is never carried on caps.
|
||||
<!-- enum VideoMultiviewMode::variant Mono -->
|
||||
All frames are monoscopic.
|
||||
<!-- enum VideoMultiviewMode::variant Left -->
|
||||
All frames represent a left-eye view.
|
||||
<!-- enum VideoMultiviewMode::variant Right -->
|
||||
All frames represent a right-eye view.
|
||||
<!-- enum VideoMultiviewMode::variant SideBySide -->
|
||||
Left and right eye views are
|
||||
provided in the left and right half of the frame respectively.
|
||||
<!-- enum VideoMultiviewMode::variant SideBySideQuincunx -->
|
||||
Left and right eye
|
||||
views are provided in the left and right half of the frame, but
|
||||
have been sampled using quincunx method, with half-pixel offset
|
||||
between the 2 views.
|
||||
<!-- enum VideoMultiviewMode::variant ColumnInterleaved -->
|
||||
Alternating vertical
|
||||
columns of pixels represent the left and right eye view respectively.
|
||||
<!-- enum VideoMultiviewMode::variant RowInterleaved -->
|
||||
Alternating horizontal
|
||||
rows of pixels represent the left and right eye view respectively.
|
||||
<!-- enum VideoMultiviewMode::variant TopBottom -->
|
||||
The top half of the frame
|
||||
contains the left eye, and the bottom half the right eye.
|
||||
<!-- enum VideoMultiviewMode::variant Checkerboard -->
|
||||
Pixels are arranged with
|
||||
alternating pixels representing left and right eye views in a
|
||||
checkerboard fashion.
|
||||
<!-- enum VideoMultiviewMode::variant FrameByFrame -->
|
||||
Left and right eye views
|
||||
are provided in separate frames alternately.
|
||||
<!-- enum VideoMultiviewMode::variant MultiviewFrameByFrame -->
|
||||
Multiple
|
||||
independent views are provided in separate frames in sequence.
|
||||
This method only applies to raw video buffers at the moment.
|
||||
Specific view identification is via the `GstVideoMultiviewMeta`
|
||||
and `VideoMeta`(s) on raw video buffers.
|
||||
<!-- enum VideoMultiviewMode::variant Separated -->
|
||||
Multiple views are
|
||||
provided as separate `gst::Memory` framebuffers attached to each
|
||||
`gst::Buffer`, described by the `GstVideoMultiviewMeta`
|
||||
and `VideoMeta`(s)
|
||||
<!-- struct VideoOverlay -->
|
||||
The `VideoOverlay` interface is used for 2 main purposes :
|
||||
|
||||
* To get a grab on the Window where the video sink element is going to render.
|
||||
This is achieved by either being informed about the Window identifier that
|
||||
the video sink element generated, or by forcing the video sink element to use
|
||||
a specific Window identifier for rendering.
|
||||
* To force a redrawing of the latest video frame the video sink element
|
||||
displayed on the Window. Indeed if the `gst::Pipeline` is in `gst::State::Paused`
|
||||
state, moving the Window around will damage its content. Application
|
||||
developers will want to handle the Expose events themselves and force the
|
||||
video sink element to refresh the Window's content.
|
||||
|
||||
Using the Window created by the video sink is probably the simplest scenario,
|
||||
in some cases, though, it might not be flexible enough for application
|
||||
developers if they need to catch events such as mouse moves and button
|
||||
clicks.
|
||||
|
||||
Setting a specific Window identifier on the video sink element is the most
|
||||
flexible solution but it has some issues. Indeed the application needs to set
|
||||
its Window identifier at the right time to avoid internal Window creation
|
||||
from the video sink element. To solve this issue a `gst::Message` is posted on
|
||||
the bus to inform the application that it should set the Window identifier
|
||||
immediately. Here is an example on how to do that correctly:
|
||||
|
||||
```text
|
||||
static GstBusSyncReply
|
||||
create_window (GstBus * bus, GstMessage * message, GstPipeline * pipeline)
|
||||
{
|
||||
// ignore anything but 'prepare-window-handle' element messages
|
||||
if (!gst_is_video_overlay_prepare_window_handle_message (message))
|
||||
return GST_BUS_PASS;
|
||||
|
||||
win = XCreateSimpleWindow (disp, root, 0, 0, 320, 240, 0, 0, 0);
|
||||
|
||||
XSetWindowBackgroundPixmap (disp, win, None);
|
||||
|
||||
XMapRaised (disp, win);
|
||||
|
||||
XSync (disp, FALSE);
|
||||
|
||||
gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (GST_MESSAGE_SRC (message)),
|
||||
win);
|
||||
|
||||
gst_message_unref (message);
|
||||
|
||||
return GST_BUS_DROP;
|
||||
}
|
||||
...
|
||||
int
|
||||
main (int argc, char **argv)
|
||||
{
|
||||
...
|
||||
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
|
||||
gst_bus_set_sync_handler (bus, (GstBusSyncHandler) create_window, pipeline,
|
||||
NULL);
|
||||
...
|
||||
}
|
||||
```
|
||||
|
||||
## Two basic usage scenarios
|
||||
|
||||
There are two basic usage scenarios: in the simplest case, the application
|
||||
uses `playbin` or `plasink` or knows exactly what particular element is used
|
||||
for video output, which is usually the case when the application creates
|
||||
the videosink to use (e.g. `xvimagesink`, `ximagesink`, etc.) itself; in this
|
||||
case, the application can just create the videosink element, create and
|
||||
realize the window to render the video on and then
|
||||
call `VideoOverlay::set_window_handle` directly with the XID or native
|
||||
window handle, before starting up the pipeline.
|
||||
As `playbin` and `playsink` implement the video overlay interface and proxy
|
||||
it transparently to the actual video sink even if it is created later, this
|
||||
case also applies when using these elements.
|
||||
|
||||
In the other and more common case, the application does not know in advance
|
||||
what GStreamer video sink element will be used for video output. This is
|
||||
usually the case when an element such as `autovideosink` is used.
|
||||
In this case, the video sink element itself is created
|
||||
asynchronously from a GStreamer streaming thread some time after the
|
||||
pipeline has been started up. When that happens, however, the video sink
|
||||
will need to know right then whether to render onto an already existing
|
||||
application window or whether to create its own window. This is when it
|
||||
posts a prepare-window-handle message, and that is also why this message needs
|
||||
to be handled in a sync bus handler which will be called from the streaming
|
||||
thread directly (because the video sink will need an answer right then).
|
||||
|
||||
As response to the prepare-window-handle element message in the bus sync
|
||||
handler, the application may use `VideoOverlay::set_window_handle` to tell
|
||||
the video sink to render onto an existing window surface. At this point the
|
||||
application should already have obtained the window handle / XID, so it
|
||||
just needs to set it. It is generally not advisable to call any GUI toolkit
|
||||
functions or window system functions from the streaming thread in which the
|
||||
prepare-window-handle message is handled, because most GUI toolkits and
|
||||
windowing systems are not thread-safe at all and a lot of care would be
|
||||
required to co-ordinate the toolkit and window system calls of the
|
||||
different threads (Gtk+ users please note: prior to Gtk+ 2.18
|
||||
GDK_WINDOW_XID() was just a simple structure access, so generally fine to do
|
||||
within the bus sync handler; this macro was changed to a function call in
|
||||
Gtk+ 2.18 and later, which is likely to cause problems when called from a
|
||||
sync handler; see below for a better approach without GDK_WINDOW_XID()
|
||||
used in the callback).
|
||||
|
||||
## GstVideoOverlay and Gtk+
|
||||
|
||||
|
||||
```text
|
||||
#include <gst/video/videooverlay.h>
|
||||
#include <gtk/gtk.h>
|
||||
#ifdef GDK_WINDOWING_X11
|
||||
#include <gdk/gdkx.h> // for GDK_WINDOW_XID
|
||||
#endif
|
||||
#ifdef GDK_WINDOWING_WIN32
|
||||
#include <gdk/gdkwin32.h> // for GDK_WINDOW_HWND
|
||||
#endif
|
||||
...
|
||||
static guintptr video_window_handle = 0;
|
||||
...
|
||||
static GstBusSyncReply
|
||||
bus_sync_handler (GstBus * bus, GstMessage * message, gpointer user_data)
|
||||
{
|
||||
// ignore anything but 'prepare-window-handle' element messages
|
||||
if (!gst_is_video_overlay_prepare_window_handle_message (message))
|
||||
return GST_BUS_PASS;
|
||||
|
||||
if (video_window_handle != 0) {
|
||||
GstVideoOverlay *overlay;
|
||||
|
||||
// GST_MESSAGE_SRC (message) will be the video sink element
|
||||
overlay = GST_VIDEO_OVERLAY (GST_MESSAGE_SRC (message));
|
||||
gst_video_overlay_set_window_handle (overlay, video_window_handle);
|
||||
} else {
|
||||
g_warning ("Should have obtained video_window_handle by now!");
|
||||
}
|
||||
|
||||
gst_message_unref (message);
|
||||
return GST_BUS_DROP;
|
||||
}
|
||||
...
|
||||
static void
|
||||
video_widget_realize_cb (GtkWidget * widget, gpointer data)
|
||||
{
|
||||
#if GTK_CHECK_VERSION(2,18,0)
|
||||
// Tell Gtk+/Gdk to create a native window for this widget instead of
|
||||
// drawing onto the parent widget.
|
||||
// This is here just for pedagogical purposes, GDK_WINDOW_XID will call
|
||||
// it as well in newer Gtk versions
|
||||
if (!gdk_window_ensure_native (widget->window))
|
||||
g_error ("Couldn't create native window needed for GstVideoOverlay!");
|
||||
#endif
|
||||
|
||||
#ifdef GDK_WINDOWING_X11
|
||||
{
|
||||
gulong xid = GDK_WINDOW_XID (gtk_widget_get_window (video_window));
|
||||
video_window_handle = xid;
|
||||
}
|
||||
#endif
|
||||
#ifdef GDK_WINDOWING_WIN32
|
||||
{
|
||||
HWND wnd = GDK_WINDOW_HWND (gtk_widget_get_window (video_window));
|
||||
video_window_handle = (guintptr) wnd;
|
||||
}
|
||||
#endif
|
||||
}
|
||||
...
|
||||
int
|
||||
main (int argc, char **argv)
|
||||
{
|
||||
GtkWidget *video_window;
|
||||
GtkWidget *app_window;
|
||||
...
|
||||
app_window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
|
||||
...
|
||||
video_window = gtk_drawing_area_new ();
|
||||
g_signal_connect (video_window, "realize",
|
||||
G_CALLBACK (video_widget_realize_cb), NULL);
|
||||
gtk_widget_set_double_buffered (video_window, FALSE);
|
||||
...
|
||||
// usually the video_window will not be directly embedded into the
|
||||
// application window like this, but there will be many other widgets
|
||||
// and the video window will be embedded in one of them instead
|
||||
gtk_container_add (GTK_CONTAINER (ap_window), video_window);
|
||||
...
|
||||
// show the GUI
|
||||
gtk_widget_show_all (app_window);
|
||||
|
||||
// realize window now so that the video window gets created and we can
|
||||
// obtain its XID/HWND before the pipeline is started up and the videosink
|
||||
// asks for the XID/HWND of the window to render onto
|
||||
gtk_widget_realize (video_window);
|
||||
|
||||
// we should have the XID/HWND now
|
||||
g_assert (video_window_handle != 0);
|
||||
...
|
||||
// set up sync handler for setting the xid once the pipeline is started
|
||||
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
|
||||
gst_bus_set_sync_handler (bus, (GstBusSyncHandler) bus_sync_handler, NULL,
|
||||
NULL);
|
||||
gst_object_unref (bus);
|
||||
...
|
||||
gst_element_set_state (pipeline, GST_STATE_PLAYING);
|
||||
...
|
||||
}
|
||||
```
|
||||
|
||||
## GstVideoOverlay and Qt
|
||||
|
||||
|
||||
```text
|
||||
#include <glib.h>
|
||||
#include <gst/gst.h>
|
||||
#include <gst/video/videooverlay.h>
|
||||
|
||||
#include <QApplication>
|
||||
#include <QTimer>
|
||||
#include <QWidget>
|
||||
|
||||
int main(int argc, char *argv[])
|
||||
{
|
||||
if (!g_thread_supported ())
|
||||
g_thread_init (NULL);
|
||||
|
||||
gst_init (&argc, &argv);
|
||||
QApplication app(argc, argv);
|
||||
app.connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit ()));
|
||||
|
||||
// prepare the pipeline
|
||||
|
||||
GstElement *pipeline = gst_pipeline_new ("xvoverlay");
|
||||
GstElement *src = gst_element_factory_make ("videotestsrc", NULL);
|
||||
GstElement *sink = gst_element_factory_make ("xvimagesink", NULL);
|
||||
gst_bin_add_many (GST_BIN (pipeline), src, sink, NULL);
|
||||
gst_element_link (src, sink);
|
||||
|
||||
// prepare the ui
|
||||
|
||||
QWidget window;
|
||||
window.resize(320, 240);
|
||||
window.show();
|
||||
|
||||
WId xwinid = window.winId();
|
||||
gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (sink), xwinid);
|
||||
|
||||
// run the pipeline
|
||||
|
||||
GstStateChangeReturn sret = gst_element_set_state (pipeline,
|
||||
GST_STATE_PLAYING);
|
||||
if (sret == GST_STATE_CHANGE_FAILURE) {
|
||||
gst_element_set_state (pipeline, GST_STATE_NULL);
|
||||
gst_object_unref (pipeline);
|
||||
// Exit application
|
||||
QTimer::singleShot(0, QApplication::activeWindow(), SLOT(quit()));
|
||||
}
|
||||
|
||||
int ret = app.exec();
|
||||
|
||||
window.hide();
|
||||
gst_element_set_state (pipeline, GST_STATE_NULL);
|
||||
gst_object_unref (pipeline);
|
||||
|
||||
return ret;
|
||||
}
|
||||
```
|
||||
|
||||
# Implements
|
||||
|
||||
[`VideoOverlayExt`](trait.VideoOverlayExt.html)
|
||||
<!-- trait VideoOverlayExt -->
|
||||
Trait containing all `VideoOverlay` methods.
|
||||
|
||||
# Implementors
|
||||
|
||||
[`VideoOverlay`](struct.VideoOverlay.html)
|
||||
<!-- trait VideoOverlayExt::fn expose -->
|
||||
Tell an overlay that it has been exposed. This will redraw the current frame
|
||||
in the drawable even if the pipeline is PAUSED.
|
||||
<!-- trait VideoOverlayExt::fn got_window_handle -->
|
||||
This will post a "have-window-handle" element message on the bus.
|
||||
|
||||
This function should only be used by video overlay plugin developers.
|
||||
## `handle`
|
||||
a platform-specific handle referencing the window
|
||||
<!-- trait VideoOverlayExt::fn handle_events -->
|
||||
Tell an overlay that it should handle events from the window system. These
|
||||
events are forwarded upstream as navigation events. In some window system,
|
||||
events are not propagated in the window hierarchy if a client is listening
|
||||
for them. This method allows you to disable events handling completely
|
||||
from the `VideoOverlay`.
|
||||
## `handle_events`
|
||||
a `gboolean` indicating if events should be handled or not.
|
||||
<!-- trait VideoOverlayExt::fn prepare_window_handle -->
|
||||
This will post a "prepare-window-handle" element message on the bus
|
||||
to give applications an opportunity to call
|
||||
`VideoOverlay::set_window_handle` before a plugin creates its own
|
||||
window.
|
||||
|
||||
This function should only be used by video overlay plugin developers.
|
||||
<!-- trait VideoOverlayExt::fn set_render_rectangle -->
|
||||
Configure a subregion as a video target within the window set by
|
||||
`VideoOverlay::set_window_handle`. If this is not used or not supported
|
||||
the video will fill the area of the window set as the overlay to 100%.
|
||||
By specifying the rectangle, the video can be overlayed to a specific region
|
||||
of that window only. After setting the new rectangle one should call
|
||||
`VideoOverlay::expose` to force a redraw. To unset the region pass -1 for
|
||||
the `width` and `height` parameters.
|
||||
|
||||
This method is needed for non fullscreen video overlay in UI toolkits that
|
||||
do not support subwindows.
|
||||
## `x`
|
||||
the horizontal offset of the render area inside the window
|
||||
## `y`
|
||||
the vertical offset of the render area inside the window
|
||||
## `width`
|
||||
the width of the render area inside the window
|
||||
## `height`
|
||||
the height of the render area inside the window
|
||||
|
||||
# Returns
|
||||
|
||||
`false` if not supported by the sink.
|
||||
<!-- trait VideoOverlayExt::fn set_window_handle -->
|
||||
This will call the video overlay's set_window_handle method. You
|
||||
should use this method to tell to an overlay to display video output to a
|
||||
specific window (e.g. an XWindow on X11). Passing 0 as the `handle` will
|
||||
tell the overlay to stop using that window and create an internal one.
|
||||
## `handle`
|
||||
a handle referencing the window.
|
||||
<!-- enum VideoTileMode -->
|
||||
Enum value describing the available tiling modes.
|
||||
<!-- enum VideoTileMode::variant Unknown -->
|
||||
Unknown or unset tile mode
|
||||
<!-- enum VideoTileMode::variant Zflipz2x2 -->
|
||||
Every four adjacent blocks - two
|
||||
horizontally and two vertically are grouped together and are located
|
||||
in memory in Z or flipped Z order. In case of odd rows, the last row
|
||||
of blocks is arranged in linear order.
|
||||
<!-- enum VideoTransferFunction -->
|
||||
The video transfer function defines the formula for converting between
|
||||
non-linear RGB (R'G'B') and linear RGB
|
||||
<!-- enum VideoTransferFunction::variant Unknown -->
|
||||
unknown transfer function
|
||||
<!-- enum VideoTransferFunction::variant Gamma10 -->
|
||||
linear RGB, gamma 1.0 curve
|
||||
<!-- enum VideoTransferFunction::variant Gamma18 -->
|
||||
Gamma 1.8 curve
|
||||
<!-- enum VideoTransferFunction::variant Gamma20 -->
|
||||
Gamma 2.0 curve
|
||||
<!-- enum VideoTransferFunction::variant Gamma22 -->
|
||||
Gamma 2.2 curve
|
||||
<!-- enum VideoTransferFunction::variant Bt709 -->
|
||||
Gamma 2.2 curve with a linear segment in the lower
|
||||
range
|
||||
<!-- enum VideoTransferFunction::variant Smpte240m -->
|
||||
Gamma 2.2 curve with a linear segment in the
|
||||
lower range
|
||||
<!-- enum VideoTransferFunction::variant Srgb -->
|
||||
Gamma 2.4 curve with a linear segment in the lower
|
||||
range
|
||||
<!-- enum VideoTransferFunction::variant Gamma28 -->
|
||||
Gamma 2.8 curve
|
||||
<!-- enum VideoTransferFunction::variant Log100 -->
|
||||
Logarithmic transfer characteristic
|
||||
100:1 range
|
||||
<!-- enum VideoTransferFunction::variant Log316 -->
|
||||
Logarithmic transfer characteristic
|
||||
316.22777:1 range
|
||||
<!-- enum VideoTransferFunction::variant Bt202012 -->
|
||||
Gamma 2.2 curve with a linear segment in the lower
|
||||
range. Used for BT.2020 with 12 bits per
|
||||
component. Since: 1.6.
|
||||
<!-- enum VideoTransferFunction::variant Adobergb -->
|
||||
Gamma 2.19921875. Since: 1.8
|
||||
Loading…
Reference in a new issue