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A device can support more than one colorspace for a given image dimension and pixel format. So we have to probe all the supported colorspace and not only rely on the default one. Otherwise we could end up with negotiation failure if the caps colorimetry field don't match the v4l2 device default one even if the v4l2 could support such colorimetry. This patch enable probing if colorspace for both capture and output device. It really makes sense for output device since the colorspace shall be set by the application and a little less for capture device which, at the moment, shall provide the colorspace; ie: the v4l2 specification seems to not take into account the fact that a capture device could do colorspace conversion. As a side effet, probing takes some times and so sligthly delay v4l2 initialization. Note that this patch only probe colorspace and not all colorspace, matrix, transfer and range combination to avoid taking too much time, especially with low-speed devices as full probing do 1782 ioctl. https://bugzilla.gnome.org/show_bug.cgi?id=755937 |
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|---|---|---|
| .. | ||
| ext | ||
| gstv4l2.c | ||
| gstv4l2allocator.c | ||
| gstv4l2allocator.h | ||
| gstv4l2bufferpool.c | ||
| gstv4l2bufferpool.h | ||
| gstv4l2colorbalance.c | ||
| gstv4l2colorbalance.h | ||
| gstv4l2deviceprovider.c | ||
| gstv4l2deviceprovider.h | ||
| gstv4l2object.c | ||
| gstv4l2object.h | ||
| gstv4l2radio.c | ||
| gstv4l2radio.h | ||
| gstv4l2sink.c | ||
| gstv4l2sink.h | ||
| gstv4l2src.c | ||
| gstv4l2src.h | ||
| gstv4l2transform.c | ||
| gstv4l2transform.h | ||
| gstv4l2tuner.c | ||
| gstv4l2tuner.h | ||
| gstv4l2videodec.c | ||
| gstv4l2videodec.h | ||
| gstv4l2vidorient.c | ||
| gstv4l2vidorient.h | ||
| Makefile.am | ||
| README | ||
| tuner.c | ||
| tuner.h | ||
| tunerchannel.c | ||
| tunerchannel.h | ||
| tunernorm.c | ||
| tunernorm.h | ||
| v4l2-utils.c | ||
| v4l2-utils.h | ||
| v4l2_calls.c | ||
| v4l2_calls.h | ||
v4l2 plugins
============
The idea is a bit the same as the idea for the v4l1 plugins. We want
one generic v4l2element, and a few child objects (probably only two:
v4l2src and v4l2sink):
/-------- v4l2src
v4l2element ---=
\-------- v4l2sink
Both v4l2src and v4l2sink have a uncompressed and a compressed
recording-/playback-mode. Since this is all part of v4l2, the 'client'
of these elements, i.e. an application using v4l2src/v4l2sink, will
hardly notice this. All capsnego stuff is done inside, and the plugin
knows which formats are compressed and which are not.
Please note that the v4l1 and the v4l2 plugins are *not* compatible
concerning properties. Naming has been kept the same where possible,
but in some cases, properties had to be removed or added to make
full use of v4l2.
V4L2 API: http://linux.bytesex.org/v4l2/.
http://v4l2spec.bytesex.org/
/usr/include/linux/videodev2.h or
Kernel patches available from
http://dl.bytesex.org/patches/.
Articles:
http://lwn.net/Articles/203924/