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• FFMPEG color range cropped to 15-235 in RGB

  20 décembre 2017, par Some1Else

  I have a series of BMPs (or PNG) images that I want to convert to XVID and MP5 movie formats.

  Encoding works but the resulting movie has a washed out color look to it and the blacks are somehow moved to RGB 16 and the brightest 255 values are moved down to 235. I want the output movie to use the same 0 to 255 colors as the source frames.

  Now there are all sorts of conflicting doco out there for FFMPEG so I am hopinbg someone has an example command line that does what I need. I have tried all sorts of pix_fmt flags but none of them get the output movie in the full color range.

  For XVID

  ffmpeg.exe -framerate 60 -i "D:\SRC%05d.BMP"  -c:v mpeg4 -vtag xvid -qscale 1 -y "D:\OUTPUT.AVI""

  For H265

  ffmpeg.exe -framerate 60 -i "D:\SRC%05d.BMP" -c:v libx265 -x265-params lossless=1 -s 3840x2160 -pix_fmt yuvj420p -an -y "D:\OUTPUT.MP4""

  The yuvj420p is supposed to give the full color range but ffmpeg complains "Incompatible pixel format ’yuvj420p’ for codec ’libx265’, auto-selecting format ’yuv420p’"

  So, are there any FFMPEG gurus out there that can give me the magic switches to get my output movies with black blacks and colors that maintain the original frame files 0-255 RGB values.

• 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 ?