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• avcodec/ljpegenc : Allow full range yuv420p, yuv422p, yuv444p by default

  6 avril 2021, par Andreas Rheinhardt

  avcodec/ljpegenc : Allow full range yuv420p, yuv422p, yuv444p by default
  The documentation for AV_PIX_FMT_YUVJ420P reads :
  
  "planar YUV 4:2:0, 12bpp, full scale (JPEG), deprecated in favor of
  
  AV_PIX_FMT_YUV420P and setting color_range"
  
  Yet the LJPEG encoder only accepts full scale yuv420p when strictness is
  
  set to unofficial or lower ; with default strictness it emits a nonsense
  
  error message that says that limit range YUV is unofficial. This has
  
  been changed to allow full range yuv420p, yuv422p and yuv444p irrespective
  
  of the level of strictness.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/ljpegenc.c

• Merge two videos with different HTTP Range header bytes

  5 avril 2022, par Mohammad Momeni

  I want to save 10 seconds from any part of a video by using its URL (without downloading it completely).
the server supports the Range header and it's possible to get specific byte ranges, the video is ok when I save it with something like Range: bytes=0-102400 but when I change the start byte and save a video with Range: bytes=307200-614400 it's no longer playable.

  


  I know maybe it lacks a MIME/header type that should be at the beginning of a file, but the first bytes are not in this response to specify the correct format of the file.
so I saved the video from 0-102400, which is ok and playable, and wanted to get that specific range and somehow append it after the first file to have both a correct file header (less than 1 sec) and that middle part of the video.

  


  first.webm Range : bytes=0-102400 (valid playable file)

  


  middle.webm Range : bytes=307200-614400 (not playable file)

  


  I tried to merge them using this command recommended by this answer

  


  ffmpeg -f concat -i list.txt -c copy merged.webm


  


  logs :

  


  [matroska,webm @ 000002143c3e77c0] File ended prematurely00 bitrate=3752.0kbits/s speed=N/A
[matroska,webm @ 000002143c429e40] Format matroska,webm detected only with low score of 1, misdetection possible!
[matroska,webm @ 000002143c429e40] EBML header parsing failed
[concat @ 000002143c3dda80] Impossible to open 'middle.webm'
list.txt: Invalid data found when processing input
frame=   42 fps=0.0 q=-1.0 Lsize=      10kB time=00:00:01.64 bitrate=  48.7kbits/s speed= 231x    
video:9kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 8.500000%


  


  generated video only shows the first video (which was already playable before merging) and ends.
I inspired this idea from this answer and don't want to download the complete video. If I can't merge them is it possible and how to write a MIME/header for the middle.webm manually to make it a valid playable video ?

  


• avformat/matroskadec : Fix probing of unknown-length headers

  17 mai 2019, par Andreas Rheinhardt

  avformat/matroskadec : Fix probing of unknown-length headers
  matroska_probe did not support the case of an unknown-length EBML header
  
  at all ; given that libavformat's Matroska muxer used to produce such
  
  files in the streaming case, support for them has been added.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskadec.c