Philipp Zabel 02d3f9748b v4l2object: improve colorspace handling for JPEG sources
gstjpegdec sets 1:4:0:0 colorimetry (full range BT.601 YCbCr encoding
with unknown primaries and unknown transfer function). This currently
gets translated to bt601 or bt709 depending on resolution.
Both cases result in a negotiation failure:

    ERROR: from element /GstPipeline:pipeline0/v4l2video0convert:v4l2video0convert0: Device '/dev/video0' does not support 1:4:0:0 colorimetry

Improve the guessing game by selecting JPEG colorimetry (JPEG colorspace
with sRGB transfer function) under these specific conditions, and loosen
the matching so that 1:4:0:0 input gets accepted if the device is
actually configured to 1:4:7:1 (V4L2_PIX_FMT_JPEG default).

https://bugzilla.gnome.org/show_bug.cgi?id=796940
2018-08-21 12:01:41 -04:00
..
2018-07-13 22:58:57 -04:00
2012-11-04 00:07:18 +00:00
2017-02-27 00:34:19 +00:00
2017-02-27 00:34:19 +00:00
2017-08-01 16:01:11 -04:00
2007-02-22 14:35:28 +00:00
2012-11-04 00:07:18 +00:00
2012-11-04 00:07:18 +00:00

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/