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• avcodec/sanm : better frame size detection for old codecs

  11 mars, par Manuel Lauss

  avcodec/sanm : better frame size detection for old codecs
  The size of the video frame (FOBJ) of the old codecs (ANIMv0/1/2) can
  
  very reliably be determined :
  
   ANIMv0/1 (=Rebel Assault 1) uses a 384x242 internal buffer for
  
    everything.  The codec parameters only describe the size and offset
  
    of the specific FOBJ on that buffer.
  
   ANIMv2 titles usually use one of the fullscreen codecs (37/47/48)
  
    as first FOBJ, and their dimensions can generally be trusted.
  
   RA2 uses 424x260 as internal buffer, use that if encountered :
  
    08PLAY.SAN does not use codec37 so we need to guess using the
  
    codec coordinates.
  
   ignore sizes smaller than 2x2 or larger than 800x600.
  
   some game videos have an initial fobj with either 1x1 or -1x-1
  
    pixels in size, ignore them with a warning (Full Throttle
  
    and the Rebel Assault 2 xxRETRY.SAN videos).
  Once a known/valid dimension set has been discovered, use it and
  
  don't change it for subsequent FOBJs, rather clamp the large frame
  
  to the determined dimensions.
  Tested with RA1, RA2, Full Throttle, Dig, Outlaws, SotE and MotS
  
  videos.
  Signed-off-by : Manuel Lauss <manuel.lauss@gmail.com>
  

  • [DH] libavcodec/sanm.c

• `ffmpeg -f concat` don't work when all input streams appear to have the same spec

  2 octobre 2024, par Roy

  My ffmpeg command :

  


  ffmpeg -safe 0 -f concat -i list.txt -c copy out.mp4


  


  My 1st input file :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'D:\Applications\ffmpeg_6.0_full\a.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf60.3.100
  Duration: 00:00:04.97, start: 0.000000, bitrate: 40 kb/s
  Stream #0:0[0x1](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 2 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 27 kb/s, 30 fps, 30 tbr, 30k tbn (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      encoder         : Lavc60.3.100 libx264


  


  My 2nd input file :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'D:\Applications\ffmpeg_6.0_full\b.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp41isom
    creation_time   : 2023-03-08T06:47:13.000000Z
    artist          : Microsoft Game DVR
    title           : PUBG: BATTLEGROUNDS
  Duration: 00:10:00.16, start: 0.000000, bitrate: 20885 kb/s
  Stream #0:0[0x1](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 20739 kb/s, 30 fps, 30 tbr, 30k tbn (default)
    Metadata:
      creation_time   : 2023-03-08T06:47:13.000000Z
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 131 kb/s (default)
    Metadata:
      creation_time   : 2023-03-08T06:47:13.000000Z
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]


  


  The above command outputs some warning signals :

  


  [mov,mp4,m4a,3gp,3g2,mj2 @ 0000025239902d40] Auto-inserting h264_mp4toannexb bitstream filter
[mp4 @ 00000252396fe5c0] Non-monotonous DTS in output stream 0:1; previous: 218112, current: 150024; changing to 218113. This may result in incorrect timestamps in the output file.
...
a lot of them
...
frame=25992 fps=21754 q=-1.0 Lsize= 1519621kB time=00:14:49.39 bitrate=13996.8kbits/s speed= 744x
video:9649kB audio:1519216kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown


  


  The resultant video can play the first part of the video correctly, then the video players either skips directly to the end of the video (MPC-HC), or don't render anything at all while timer passes as normal (VLC).

  


  My impression of the concat is that it requires all videos to have the same spec, which I think my input achieved (all the "Steam #0:0", etc, line matches). I only see the following difference, which I assumed that should be okay :

  


  

  1. Metadata are different both for the whole input (e.g. "major_brand") and for each stream (e.g. "encoder"). I assumed that metadata won't affect the processing.

  


  2. The order of video/audio streams are different in the two inputs : the 1st input file has audio then video ; the 2nd input file has video then audio. I assumed that ffmpeg knows the difference and won't concat a video stream to an audio stream.

  


  


  The full output of the command can be found in this pastebin : https://pastebin.com/Z5q97Uyg

  


• avcodec/sanm : disable left/top for fullscreen codecs

  11 mars, par Manuel Lauss

  avcodec/sanm : disable left/top for fullscreen codecs
  The block-based codecs 37/47/48 work on the full frame, and there's no
  
  existing LucasArts game video that uses left/top offsets for these,
  
  as it doesn't make sense. Ignore the left/top parameters for these codecs.
  Signed-off-by : Manuel Lauss <manuel.lauss@gmail.com>
  

  • [DH] libavcodec/sanm.c