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• lavc/vvc : Check slice structure

  10 janvier, par Frank Plowman

  lavc/vvc : Check slice structure
  The criteria for slice structure validity is similar to that of
  
  subpicture structure validity that we saw not too long ago [1].
  
  The relationship between tiles and slices must satisfy the following
  
  properties :
  * Exhaustivity.  All tiles in a picture must belong to a slice.  The
  
    tiles cover the picture, so this implies the slices must cover the
  
    picture.
  
  * Mutual exclusivity.  No tile may belong to more than one slice, i.e.
  
    slices may not overlap.
  In most cases these properties are guaranteed by the syntax.  There is
  
  one noticable exception however : when pps_tile_idx_delta_present_flag is
  
  equal to one, each slice is associated with a syntax element
  
  pps_tile_idx_delta_val[i] which "specifies the difference between the
  
  tile index of the tile containing the first CTU in the ( i + 1 )-th
  
  rectangular slice and the tile index of the tile containing the first
  
  CTU in the i-th rectangular slice" [2].  When these syntax elements are
  
  present, the i-th slice can begin anywhere and the usual guarantees
  
  provided by the syntax are lost.
  The patch detects slice structures which violate either of the two
  
  properties above, and are therefore invalid, while building the
  
  slice map.  Should the slice map be determined to be invalid, an
  
  AVERROR_INVALIDDATA is returned.  This prevents issues including
  
  segmentation faults when trying to decode,  invalid bitstreams.
  [1] : https://ffmpeg.org//pipermail/ffmpeg-devel/2024-October/334470.html
  
  [2] : H.266 (V3) Section 7.4.3.5, Picture parameter set RBSP semantics
  Signed-off-by : Frank Plowman <post@frankplowman.com>
  

  • [DH] libavcodec/vvc/ps.c

• How to reinsert edited metadata stream information from the FFMETADATAFILE file ? [closed]

  6 septembre 2024, par SENYCH

  I'm working on simplifying and speeding up the process of editing video metadata for user convenience. I've successfully edited metadata streams using console commands, such as :

  


  ffmpeg -i INPUT.mp4 -map 0 -metadata:s:0 "handler_name=An other video" -metadata:s:1 "handler_name=An other audio recording in russian" -metadata:s:2 "handler_name=An other audio recording in english" -metadata:s:3 "handler_name=An other audio recording in japanese" -c copy OUTPUT.mp4


  


  However, I'd like to accomplish this through a ffmetadata file. Here's the approach I've taken :

  


  ffmpeg -t 0 -i INPUT.mp4 -map 0 -c copy -f ffmetadata ffmetadata.txt -hide_banner


  


  Original ffmetadata.txt is :

  


  ;FFMETADATA1
major_brand=isom
minor_version=512
compatible_brands=isomiso2avc1mp41
encoder=Lavf61.5.101
[STREAM]
language=und
handler_name=The best video
vendor_id=[0][0][0][0]
[STREAM]
language=rus
handler_name=The best russian language
vendor_id=[0][0][0][0]
[STREAM]
language=eng
handler_name=The best english language
vendor_id=[0][0][0][0]
[STREAM]
language=jpn
handler_name=The best japanese language
vendor_id=[0][0][0][0]


  


  Edit the ffmetadata.txt file to update the handler_name values :

  


  ;FFMETADATA1
major_brand=isom
minor_version=512
compatible_brands=isomiso2avc1mp41
encoder=Lavf61.5.101
[STREAM]
language=und
handler_name=An other video
vendor_id=[0][0][0][0]
[STREAM]
language=rus
handler_name=An other audio recording in russian
vendor_id=[0][0][0][0]
[STREAM]
language=eng
handler_name=An other audio recording in english
vendor_id=[0][0][0][0]
[STREAM]
language=jpn
handler_name=An other audio recording in japanese
vendor_id=[0][0][0][0]


  


  Attempt to apply the updated metadata from ffmetadata2.txt :

  


  C:\Users\Alexander\Videos>ffmpeg -i INPUT.mp4 -i ffmetadata2.txt -map 0:v -map 0:a -map_metadata 1 -c copy OUTPUT2.mp4 -hide_banner


  


  Despite these steps, I've noticed that only the global metadata is updated, while the metadata for each stream remains unchanged. The console output shows that metadata for each stream is not updated as expected.

  


  What am I missing ? How can I ensure that the stream-specific metadata is also updated correctly when using a ffmetadata file ?

  


  Additional Information :

  


  

  • FFmpeg version : 2024-08-26-git-98610fe95f-full_build

  


  • The ffmetadata file format and the approach I've used should be correct according to the FFmpeg documentation.

  


  


  I would greatly appreciate any recommendations or suggestions on how to solve this problem !

  


  I found a bad solution for my problem, but it still isn't ideal as it requires specifying -map_metadata:s:N 1:s:N for each stream individually, which is quite cumbersome. Is there a way to simplify this process and avoid having to set metadata for each stream separately ?

  


  The command I’m using is :

  


  C:\Users\Alexander\Videos>ffmpeg -i INPUT.mp4 -i ffmetadata2.txt -map 0 -map_metadata:s:0 1:s:0 -map_metadata:s:1 1:s:1 -map_metadata:s:2 1:s:2 -map_metadata:s:3 1:s:3 -c copy OUTPUT2.mp4 -hide_banner


  


  This works, but having to specify -map_metadata:s:N for each stream creates extra work, especially as the number of streams increases. Is there a more efficient way to handle this ?

  


• Empty audio backends for torchaudio list audio backends, with ffmpeg installed on system libraries [closed]

  28 mars, par Alberto Agudo Dominguez

  I installed torchaudio 2.5.1 and a system install of ffmpeg on Windows and get :

  


  PS C:\Users\> ffmpeg -version
ffmpeg version 2025-01-05-git-19c95ecbff-essentials_build-www.gyan.dev Copyright (c) 2000-2025 the FFmpeg developers
built with gcc 14.2.0 (Rev1, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-sdl2 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-dxva2 --enable-d3d11va --enable-d3d12va --enable-ffnvcodec --enable-libvpl --enable-nvdec --enable-nvenc --enable-vaapi --enable-libgme --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libtheora --enable-libvo-amrwbenc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-librubberband
libavutil      59. 54.101 / 59. 54.101
libavcodec     61. 31.100 / 61. 31.100
libavfilter    10.  6.101 / 10.  6.101
libswresample   5.  4.100 /  5.  4.100
libpostproc    58.  4.100 / 58.  4.100

PS C:\Users\> python
Python 3.12.5 (tags/v3.12.5:ff3bc82, Aug  6 2024, 20:45:27) [MSC v.1940 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import torchaudio
>>> torchaudio.list_audio_backends()
[]


  


  Hence ffmpeg is added to the path and recognized by the console, but not by torchaudio.