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• How to mimic Audacity's "truncate silence" with ffmpeg "silenceremove" filter

  16 juin 2024, par Cara Duf

  I want to remove completely silence parts from wav files with ffmpeg.

  


  Input wav can be like :


  


  I am using the following ffmpeg command to remove silence part ffmpeg -i input.wav -af silenceremove=stop_periods=-1:stop_duration=0.2:stop_threshold=-45dB output.wav because I understand from the doc that it will remove all silence parts longer than 0.2 s (silence being below -45dB).

  


  But I get that where silence part has only been reduced to around 0.1 wheras I want it to be 0 (no remaining silence).

  


  In Audacity I will use "truncate audio" filter and choose the above parameters to detect silence and in the action part I will choose to truncate to 0 : .

  


  This will yield to what I want (ie an audio with no silence part remaining) :


  


  Searching on the internet only lead me to what I already do.

  


  So how can I reproduce the output I get from Audacity "Truncate Silence" filter with ffmpeg and remove all silence parts from audio ?

  


  Edit : The output from silencedetect filter is correct : ffmpeg -i input.wav -af silencedetect=0.2:n=-45dB -f null - detects exactly what audacity detects.

  


  Thanks in advance for your help

  


• Revert "Revert "lavfi/buffersrc : push the frame deeper if requested.""

  16 juillet 2017, par Nicolas George

  Revert "Revert "lavfi/buffersrc : push the frame deeper if requested.""
  This reverts commit 04aa09c4bcf2d5a634a35da3a3ae3fc1abe30ef8
  
  and reintroduces 0ff5567a30be6d7c804e95997ae282d6bacd76c3 that
  
  was temporarily reverted due to minor regressions.
  It also reverts e5bce8b4ce7b1f3a83998febdfa86a3771df96ce that fixed FATE refs.
  
  The fate-ffm change is caused by field_order now being set
  
  on the output format because the first frame arrives earlier.
  
  The fate-mxf change is assumed to be the same.
  

  • [DH] libavfilter/buffersrc.c
  • [DH] tests/ref/lavf/ffm
  • [DH] tests/ref/lavf/mxf

• ffmpeg crashes with "Internal bug", "Failed to inject frame into filter network" while trying to convert PNG files into an animated gif using filters

  12 août 2022, par EigentlichOracler

  ffmpeg version : ffmpeg version 4.2.7-0ubuntu0.1

  


  Kernel : 5.4.0-122-lowlatency #138-Ubuntu SMP PREEMPT x86_64 x86_64 x86_64 GNU/Linux

  


  PNG-Images : 996 pieces, all equal in size : 1000x50

  


  Then trying to build palette using palettegen :

  


  export filters="scale=1000:-1:flags=lanczos"
export palette=./stripes_palette.png
ffmpeg -v warning -i ./palette_source_stripes.png -vf "$filters,palettegen=stats_mode=diff" -y $palette
[Parsed_palettegen_1 @ 0x55f0eea30e00] Dupped color: FF63000D


  


  Palette file has been created, looks good so far. Then I tried to convert all 996 PNG files into one single (space optimized) animated GIF file using paletteuse :

  


  ffmpeg -v warning -framerate 5 -thread_queue_size 2048 -i ./tmp/temp.%04d.png -i $palette -lavfi "$filters,paletteuse=dither=bayer:bayer_scale=5:diff_mode=rectangle" -r 5 -loop -1 -y testanim.gif
Error while filtering: Internal bug, should not have happened
Failed to inject frame into filter network: Internal bug, should not have happened
Error while processing the decoded data for stream #0:0


  


  The reason for "-framerate 5" for the input and "-r 5" for the output is : I wanted the animated GIF to use a determined time for running through animation. It already had worked out without using complex filtering, but the results were huge GIF files which are hard to handle.
But even when I avoid both framerate parameters, still the same error message occurs.

  


  Should I look deeper into the "Dupped color" which has been mentioned ? Did anybody encounter a similar issue using ffmpeg ?
I'm not used to deal with filters (nor "complex filters") in ffmpeg, I'm very new at this, but I've found no tips regarding an ffmpeg crash like I've right here.

  


  ------------------------------- EDIT 2022-08-12/1 ---------------------

  


  Same error occurs with current stable version
ffmpeg version 4.4.2-0ubuntu0.22.04.1 Copyright (c) 2000-2021 the FFmpeg developers

  


  ------------------------------- EDIT 2022-08-12/2 ---------------------

  


  Found workaround, see answer below