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video-color: add gst_video_color_matrix_get_Kr_Kb()

Browse source 
Move the function to get the color matrix coefficients from
videoconvert to the video library.
This commit is contained in:
Wim Taymans 2014-09-24 11:04:15 +02:00
parent 8242676dc2
commit 0c40b83ed4
5 changed files with 77 additions and 35 deletions
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1
docs/libs/gst-plugins-base-libs-sections.txt
View file

@ -2299,6 +2299,7 @@ gst_video_colorimetry_matches
gst_video_colorimetry_from_string
gst_video_colorimetry_to_string
gst_video_color_range_offsets
gst_video_color_matrix_get_Kr_Kb
<SUBSECTION Standard>
gst_video_color_range_get_type
GST_TYPE_VIDEO_COLOR_RANGE

71
gst-libs/gst/video/video-color.c
View file

@ -243,3 +243,74 @@ static const PrimariesInfo primaries[] = {
0.049}
};
#endif
/**
* gst_video_color_matrix_get_Kr_Kb:
* @matrix: a #GstVideoColorMatrix
* @Kr: result red channel coefficient
* @Kb: result blue channel coefficient
*
* Get the coefficients used to convert between Y'PbPr and R'G'B' using @matrix.
*
* When:
*
* |[
* 0.0 <= [Y',R',G',B'] <= 1.0)
* (-0.5 <= [Pb,Pr] <= 0.5)
* ]|
*
* the general conversion is given by:
*
* |[
* Y' = Kr*R' + (1-Kr-Kb)*G' + Kb*B'
* Pb = (B'-Y')/(2*(1-Kb))
* Pr = (R'-Y')/(2*(1-Kr))
* ]|
*
* and the other way around:
*
* |[
* R' = Y' + Cr*2*(1-Kr)
* G' = Y' - Cb*2*(1-Kb)*Kb/(1-Kr-Kb) - Cr*2*(1-Kr)*Kr/(1-Kr-Kb)
* B' = Y' + Cb*2*(1-Kb)
* ]|
*
* Returns: TRUE if @matrix was a YUV color format and @Kr and @Kb contain valid
* values.
*
* Since: 1.6
*/
gboolean
gst_video_color_matrix_get_Kr_Kb (GstVideoColorMatrix matrix, gdouble * Kr,
gdouble * Kb)
{
gboolean res = TRUE;
switch (matrix) {
/* RGB */
default:
case GST_VIDEO_COLOR_MATRIX_RGB:
res = FALSE;
break;
/* YUV */
case GST_VIDEO_COLOR_MATRIX_FCC:
*Kr = 0.30;
*Kb = 0.11;
break;
case GST_VIDEO_COLOR_MATRIX_BT709:
*Kr = 0.2126;
*Kb = 0.0722;
break;
case GST_VIDEO_COLOR_MATRIX_BT601:
*Kr = 0.2990;
*Kb = 0.1140;
break;
case GST_VIDEO_COLOR_MATRIX_SMPTE240M:
*Kr = 0.212;
*Kb = 0.087;
break;
}
GST_DEBUG ("matrix: %d, Kr %f, Kb %f", matrix, *Kr, *Kb);
return res;
}

2
gst-libs/gst/video/video-color.h
View file

@ -63,6 +63,8 @@ typedef enum {
GST_VIDEO_COLOR_MATRIX_SMPTE240M
} GstVideoColorMatrix;
gboolean gst_video_color_matrix_get_Kr_Kb (GstVideoColorMatrix matrix, gdouble * Kr, gdouble * Kb);
/**
* GstVideoTransferFunction:
* @GST_VIDEO_TRANSFER_UNKNOWN: unknown transfer function

37
gst/videoconvert/videoconvert.c
View file

@ -182,39 +182,6 @@ videoconvert_convert_matrix16 (VideoConvert * convert, gpointer pixels)
}
}
static gboolean
get_Kr_Kb (GstVideoColorMatrix matrix, gdouble * Kr, gdouble * Kb)
{
gboolean res = TRUE;
switch (matrix) {
/* RGB */
default:
case GST_VIDEO_COLOR_MATRIX_RGB:
res = FALSE;
break;
/* YUV */
case GST_VIDEO_COLOR_MATRIX_FCC:
*Kr = 0.30;
*Kb = 0.11;
break;
case GST_VIDEO_COLOR_MATRIX_BT709:
*Kr = 0.2126;
*Kb = 0.0722;
break;
case GST_VIDEO_COLOR_MATRIX_BT601:
*Kr = 0.2990;
*Kb = 0.1140;
break;
case GST_VIDEO_COLOR_MATRIX_SMPTE240M:
*Kr = 0.212;
*Kb = 0.087;
break;
}
GST_DEBUG ("matrix: %d, Kr %f, Kb %f", matrix, *Kr, *Kb);
return res;
}
static gboolean
videoconvert_convert_compute_matrix (VideoConvert * convert)
{
@ -283,7 +250,7 @@ videoconvert_convert_compute_matrix (VideoConvert * convert)
1 / ((float) scale[1]), 1 / ((float) scale[2]));
/* 2. bring components to R'G'B' space */
if (get_Kr_Kb (in_info->colorimetry.matrix, &Kr, &Kb))
if (gst_video_color_matrix_get_Kr_Kb (in_info->colorimetry.matrix, &Kr, &Kb))
color_matrix_YCbCr_to_RGB (&dst, Kr, Kb);
/* 3. inverse transfer function. R'G'B' to linear RGB */
@ -295,7 +262,7 @@ videoconvert_convert_compute_matrix (VideoConvert * convert)
/* 6. transfer function. linear RGB to R'G'B' */
/* 7. bring components to YCbCr space */
if (get_Kr_Kb (out_info->colorimetry.matrix, &Kr, &Kb))
if (gst_video_color_matrix_get_Kr_Kb (out_info->colorimetry.matrix, &Kr, &Kb))
color_matrix_RGB_to_YCbCr (&dst, Kr, Kb);
/* 8, bring color components to nominal range */

1
win32/common/libgstvideo.def
View file

@ -71,6 +71,7 @@ EXPORTS
gst_video_codec_state_get_type
gst_video_codec_state_ref
gst_video_codec_state_unref
gst_video_color_matrix_get_Kr_Kb
gst_video_color_matrix_get_type
gst_video_color_primaries_get_type
gst_video_color_range_get_type