[FFmpeg-trac] #1387(undetermined:new): v4l2 uses wrong (default) parameters

[FFmpeg]

#1387: v4l2 uses wrong (default) parameters
-------------------------------------+-------------------------------------
             Reporter:  burek        |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Using web cameras, usual way of setting web cam parameters is by using
 v4l2-ctl tool, to set the default width, height, pixel_format, frame_rate,
 etc. so that when we use:

 {{{
 ffmpeg -f v4l2 -i /dev/video0 ...
 }}}

 FFmpeg should use those defaults (after all, that's the purpose of such
 tool). But that doesn't happen. For example, I've got a usb web cam that
 supports input using H264 stream (beside raw and mjpeg), which is
 confirmed by v4l2-ctl:

 {{{
 $ v4l2-ctl --list-formats
 ioctl: VIDIOC_ENUM_FMT
         Index       : 0
         Type        : Video Capture
         Pixel Format: 'YUYV'
         Name        : YUV 4:2:2 (YUYV)

         Index       : 1
         Type        : Video Capture
         Pixel Format: 'H264' (compressed)
         Name        : H.264

         Index       : 2
         Type        : Video Capture
         Pixel Format: 'MJPG' (compressed)
         Name        : MJPEG
 }}}

 so, setting up some web cam defaults like this:

 {{{
 $ v4l2-ctl --all
 Driver Info (not using libv4l2):
         Driver name   : uvcvideo
         Card type     : HD Pro Webcam C920
         Bus info      : usb-0000:00:1d.7-8
         Driver version: 3.2.17
         Capabilities  : 0x04000001
                 Video Capture
                 Streaming
 Format Video Capture:
         Width/Height  : 640/480
         Pixel Format  : 'H264'
         Field         : None
         Bytes per Line: 1280
         Size Image    : 614400
         Colorspace    : SRGB
 Crop Capability Video Capture:
         Bounds      : Left 0, Top 0, Width 640, Height 480
         Default     : Left 0, Top 0, Width 640, Height 480
         Pixel Aspect: 1/1
 Video input : 0 (Camera 1: ok)
 Streaming Parameters Video Capture:
         Capabilities     : timeperframe
         Frames per second: 30.000 (30/1)
         Read buffers     : 0
 }}}

 should make Ffmpeg's command work in such way that it grabs the input from
 web cam using frame size of 640x480 and pixel_format of 'H264' (or was it
 -vcodec in FFmpeg, I'm not sure). But, running the FFmpeg command gives
 this:

 {{{
 $ ffmpeg -f v4l2 -i /dev/video0 -vcodec copy out.ts
 ffmpeg version N-41142-g8f61526 Copyright (c) 2000-2012 the FFmpeg
 developers
   built on May 30 2012 13:40:37 with gcc 4.6.3
   configuration: --enable-static --enable-shared --enable-gpl --enable-
 nonfree --enable-postproc --enable-libx264 --enable-libaacplus --enable-
 libmp3lame --enable-libopenjpeg --enable-zlib
   libavutil      51. 55.100 / 51. 55.100
   libavcodec     54. 23.100 / 54. 23.100
   libavformat    54.  6.101 / 54.  6.101
   libavdevice    54.  0.100 / 54.  0.100
   libavfilter     2. 77.100 /  2. 77.100
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0. 15.100 /  0. 15.100
   libpostproc    52.  0.100 / 52.  0.100
 [video4linux2,v4l2 @ 0x9fee420] Estimating duration from bitrate, this may
 be inaccurate
 Input #0, video4linux2,v4l2, from '/dev/video0':
   Duration: N/A, start: 175879.115402, bitrate: 147456 kb/s
     Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 640x480,
 147456 kb/s, 30 tbr, 1000k tbn, 30 tbc
 [mpegts @ 0x9febaa0] muxrate VBR, pcr every 3 pkts, sdt every 200, pat/pmt
 every 40 pkts
 Output #0, mpegts, to 'out.ts':
   Metadata:
     encoder         : Lavf54.6.101
     Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 640x480,
 q=2-31, 147456 kb/s, 90k tbn, 30 tbc
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
 Press [q] to stop, [?] for help
 frame=  113 fps= 30 q=-1.0 Lsize=   73103kB time=00:00:03.76
 bitrate=158903.9kbits/s
 video:67800kB audio:0kB global headers:0kB muxing overhead 7.822064%
 }}}

 As you can see, the input is set to "rawvideo (YUY2 / 0x32595559)" mode
 (which is wrong) and frame size is set to 640x480 (which is correct).
 Further testing shows that setting various default frame sizes, using
 v4l2-ctl, is properly detected in FFmpeg, but input pixel_format of
 H264/MJPG is not.

 P.S.
 Using the following command, I can get FFmpeg to "recognize" that I want
 input format to be mjpeg instead of raw:

 {{{
 $ ffmpeg -f v4l2 -vcodec mjpeg -i /dev/video0 ...
 ...
 Input #0, video4linux2,v4l2, from '/dev/video0':
   Duration: N/A, start: 176610.262086, bitrate: N/A
     Stream #0:0: Video: mjpeg, yuvj422p, 352x288, -5 kb/s, 30 tbr, 1000k
 tbn, 30 tbc
 }}}

 but, I can't get the same for H264, because I get error instead:

 {{{
 $ ffmpeg -y -f v4l2 -vcodec h264 -i /dev/video0 ...
 ...
 [video4linux2,v4l2 @ 0x8ca24a0] Cannot find a proper format for codec_id
 28, pix_fmt -1.
 }}}

 So, this is either some kind of bug in FFmpeg or unimplemented feature or
 something, so I don't know how to correctly flag this report.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1387>
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