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• checkasm/sw_range_convert : test all supported bit depths

  18 septembre 2024, par Ramiro Polla

  checkasm/sw_range_convert : test all supported bit depths
  This commit also reduces the number of times ff_sws_init_scale() gets
  
  called (only once per bit depth), and the number of times randomize_buffers()
  
  gets called (only if the function must be checked).
  Benchmarks are only performed on bit depths 8 and 16 (since they are
  
  different functions, and not only different constants).
  

  • [DH] tests/checkasm/sw_range_convert.c

• Is there a way to strip B frames from a .mp4 with ffmpeg script

  14 décembre 2020, par QWKSILVER

  I have a series of videos that run in a very stuttery way on my hardware. In avidemux I get an error about B frames not being linearly correct, do I wish to open, may take a long time. I open it, and then resave it, without re-encoding anything, but it fixes the issue in the new file, and the stutteryness goes away in playback.

  


  I would like to do this with ffmpeg so i can just run a script on the files that have the issue, and not have to go one at a time.

  


  So the question is, Can I strip the b-frame data, or fix it, remove any duplicate frames, leave the time/date data alone, and resave it in the same format (.mp4) without file size growing, or quality degrading, option would be to actually reencode to x265 but not required.

  


  i would also entertain a move to another format mkv, webm, if I could keep the rest stable, and have smaller or equal files. Videos will exist in multiple resolutions, but usually typical 16:9 dimension.

  


  Any help would be appreciated.

  


• Can ffmpeg write metadata encoder when transcoding alac/flac to aac audio file ?

  11 juin 2022, par David I

  I have a collection of alac and flac files from Bandcamp and an ffmpeg instance compiled with libfdk_aac https://trac.ffmpeg.org/wiki/CompilationGuide/Centos#libfdk_aac and am trying to convert these to lossy audio aac files for non-critical listening.

  


  With ffmpeg -i Liholesie\ -\ Shamanic\ Twilight\ -\ 09\ Gray\ Wings.m4a -c:a libfdk_aac -vbr 4 -c:v copy 09_Gray_wings_vbr4.m4a an expected aac .m4a audio file is produced, album art included, works well. There's one slight detail missing :

  


  During the ffmpeg conversion process ffmpeg says :

  


  Output #0, ipod, to '09_Gray_wings_vbr4.m4a':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: M4A isomiso2
    title           : Gray Wings
    artist          : Liholesie
    album_artist    : Liholesie
    album           : Shamanic Twilight
    comment         : Visit https://liholesie.bandcamp.com
    date            : 2021
    track           : 9
    encoder         : Lavf59.24.100
  Stream #0:0: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 700x700 [SAR 72:72 DAR 1:1], q=2-31, 90k tbr, 90k tbn (attached pic)
  Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, s16 (default)
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
      encoder         : Lavc59.33.100 libfdk_aac 
..




  


  and the file produced looks like that when ffprobed except that the Metadata : encoder field is missing :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '09_Gray_wings_vbr4.m4a':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: M4A isomiso2
    title           : Gray Wings
    artist          : Liholesie
    album_artist    : Liholesie
    album           : Shamanic Twilight
    date            : 2021
    encoder         : Lavf59.24.100
    comment         : Visit https://liholesie.bandcamp.com
    track           : 9
  Duration: 00:06:57.78, start: 0.000000, bitrate: 155 kb/s
  Stream #0:0[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x0]: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 700x700 [SAR 72:72 DAR 1:1], 90k tbr, 90k tbn (attached pic)


  


  Is there a way to write the encoder field in the Metadata section when transcoding (or is "encoder" not supported for aac m4a ? That would be weird since ffmpeg says what it says when specifying output during transcoding) .

  


  Any hints on how to write a self-defined text to said tag during transcoding are also welcome.