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• avcodec/cbs_av1 : Avoid shift overflow

  1er mai 2024, par Michael Niedermayer

  avcodec/cbs_av1 : Avoid shift overflow
  Fixes : CID1465488 Unintentional integer overflow
  Sponsored-by : Sovereign Tech Fund
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/cbs_av1.c

• How to record video from old webcam using ffmpeg on Linux ?

  5 février 2015, par Moomin

  After couple of hours I finally accepted my absolute lack of knowledge and decided to post this question here.
  I’m trying to record video from an old external USB webcam (Media-Tech MT400 -> 0c45:6029) with ffmpeg but without much success.

  First thing I’ve tried was to run to try something that works for the built-in webcam) :

  ffmpeg -f v4l2 -i /dev/video1 test.avi

  But that returned a following error :

  Cannot find a proper format for codec 'none' (id 0), pixel format 'none' (id -1)

  Here is what I get from v4l2-ctl -d /dev/video1/ --all --list-formats-ext

  Driver Info (not using libv4l2):
  
          Driver name   : sonixb
  
          Card type     : USB camera
  
          Bus info      : usb-0000:04:00.0-1
  
          Driver version: 3.10.17
  
          Capabilities  : 0x85000001
  
                  Video Capture
  
                  Read/Write
  
                  Streaming
  
                  Device Capabilities
  
          Device Caps   : 0x05000001
  
                  Video Capture
  
                  Read/Write
  
                  Streaming
  
  Priority: 2
  
  Video input : 0 (sonixb: ok)
  
  Format Video Capture:
  
          Width/Height  : 352/288
  
          Pixel Format  : 'S910'
  
          Field         : None
  
          Bytes per Line: 352
  
          Size Image    : 126720
  
          Colorspace    : SRGB
  
  Streaming Parameters Video Capture:
  
          Frames per second: invalid (0/0)
  
          Read buffers     : 2
  
  
  
  
  
  
  
  ioctl: VIDIOC_ENUM_FMT
  
      Index       : 0
  
      Type        : Video Capture
  
      Pixel Format: 'S910'
  
      Name        : S910
  
              Size: Discrete 160x120
  
              Size: Discrete 176x144
  
              Size: Discrete 320x240
  
              Size: Discrete 352x288
  
  
  
      Index       : 1
  
      Type        : Video Capture
  
      Pixel Format: 'BA81'
  
      Name        : BA81
  
              Size: Discrete 160x120
  
              Size: Discrete 176x144

  Unfortunately that was not of much help to me, but I tried capturing webcam output with VLC and recording it which.... WORKED !

  I tried ffmpeg -i vlc-record[...].avi on VLC recording which returned following information :

  Input #0, avi, from 'vlc-record-2015-02-05-05h22m52s-v4l2____dev_video1-.avi':
  
    Duration: 00:00:01.58, start: 0.000000, bitrate: 26937 kb/s
  
      Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 352x288, 27671 kb/s, 22.10 tbr, 22.10 tbn, 22.10 tbc

  I thought that was enough information (rawvideo and yuv420p) led to run ffmpeg with following arguments (I have found yuv4 using ffmpeg -formats)

  ffmpeg -f rawvideo -vcodec yuv4 -i /dev/video1 test.avi

  The result was only slightly better than one that I saw after my first attempt :

  [IMGUTILS @ 0x7fff497d3920] Picture size 0x0 is invalid
  
  [rawvideo @ 0x9c4720] Could not find codec parameters for stream 0 (Video: yuv4, yuv420p, -4 kb/s): unspecified size
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  /dev/video1: could not find codec parameters

  Again after some searching and several tries I added ’-video_size cif` option and.... it WORKED !!!!

  Well, not really...

  Input #0, rawvideo, from '/dev/video1':
  
    Duration: N/A, start: 0.000000, bitrate: 30412 kb/s
  
      Stream #0:0: Video: yuv4, yuv420p, 352x288, 30412 kb/s, 25 tbr, 25 tbn, 25 tbc
  
  Output #0, avi, to 'test.avi':
  
    Metadata:
  
      ISFT            : Lavf55.19.104
  
      Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 352x288, q=2-31, 200 kb/s, 25 tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (yuv4 -> mpeg4)
  
  Press [q] to stop, [?] for help
  
  frame=   13 fps=6.3 q=24.8 Lsize=    1064kB time=00:00:00.52 bitrate=16759.3kbits/s    
  
  video:1058kB audio:0kB subtitle:0 global headers:0kB muxing overhead 0.554114%

  LED on webcam turned on as during capturing video with VLC but all that was recorded was TV-like noise.

  So here I am after 7 hours - still without work solution - asking for your help.

  Thanks in advance.

• avcodec/dovi_rpuenc : Initialize bl_compat_id

  3 mai 2024, par Michael Niedermayer

  avcodec/dovi_rpuenc : Initialize bl_compat_id
  Fixes : CID1596607 Uninitialized scalar variable
  Sponsored-by : Sovereign Tech Fund
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/dovi_rpuenc.c