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• Revision 37442 : On se base sur la valeur de l’id_orig pour vérifier si l’on doit mettre ...

  20 avril 2010, par kent1@… — Log

  On se base sur la valeur de l’id_orig pour vérifier si l’on doit mettre dans la file d’encodage et non pas sur le nom de fichier
  Incrément mineur de version

• avcodec/webp : Use LE VLC table for LE bitstream reader

  12 octobre 2020, par Andreas Rheinhardt

  avcodec/webp : Use LE VLC table for LE bitstream reader
  The WebP format uses Huffman tables and the decoder therefore uses
  
  VLC tables. Given that WebP is a LE format, a LE bitreader is used ;
  
  yet the VLC table is not created for a LE reader (the process used to
  
  create the tables puts the last bit to be read in the lowest bit) and
  
  therefore custom code for reading the VLCs that reverses the bits
  
  read is used instead of get_vlc2(). This commit changes this to use
  
  a table designed for LE bitreader which allows to use get_vlc2() directly.
  
  The necessary reversing of the codes is delegated to
  
  ff_init_vlc_sparse() (and is therefore only done during init and not
  
  when actually reading the VLCs).
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/webp.c

• FFMPEG Chapter Metadata added to a song file is sometimes off by 1 second

  6 février 2021, par Elthfa

  I attempted to add chapter metadata to a .opus file, but afterward, the file metadata showed timestamps different than the ones I attempted to add.
It seems to be adding an extra second to the timestamps under certain conditions.
I'm not sure if this is a bug, or if maybe I am just using the command wrong.

  


  Here are the commands I performed :

  


  First I removed all existing metadata from the file. I did this using a command I found on stack overflow :

  


  ffmpeg -i test_song.opus -c copy -map_metadata -1 -fflags +bitexact -flags:a +bitexact no_metadata.opus


  


  Then I added the new metadata from an external file I had written :

  


  ffmpeg -i no_metadata.opus -f ffmetadata -i metadata.txt -c copy -map_metadata 1 out.opus


  


  The file 'metadata.txt' looks like :

  


  ;FFMETADATA1
[CHAPTER]
TIMEBASE=1/1000
START=0
END=400
title=400 ms
[CHAPTER]
TIMEBASE=1/1000
START=400
END=500
title=100 ms
[CHAPTER]
TIMEBASE=1/1000
START=500
END=2000s
title=1500 ms
[CHAPTER]
TIMEBASE=1/1000
START=2000
END=97000
title=The Rest


  


  When I print out the basic data from the file, not all the timestamps shown match the ones I had in the metadata file.

  


  > ffmpeg -i out.opus
...
Input #0, ogg, from 'out.opus':
  Duration: 00:01:37.00, start: 0.000000, bitrate: 147 kb/s

    Chapter #0:0: start 0.000000, end 0.400000
    Metadata:
      title           : 400 ms

    Chapter #0:1: start 0.400000, end 1.500000
    Metadata:
      title           : 100 ms
    
    Chapter #0:2: start 1.500000, end 2.000000
    Metadata:
      title           : 1500 ms
    
    Chapter #0:3: start 2.000000, end 97.000000
    Metadata:
      title           : The Rest
...


  


  You can see the issues for chapters 0:1 and 0:2, which show a start and end time of 1.5 seconds respectively, when it should be 0.5 seconds for each.
I tried several combinations for this, and it seems that if the digit in the hundreds of milliseconds place is between 5 and 9 inclusive, it adds and extra second to the timestamp it saves in the metadata.

  


  Is this due to me using the command wrong ? Or formatting the metadata file wrong ? Or is there an issue in the code with rounding timestamps ?

  


  Thanks !