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• When I append a silent audio (mp3) to an existing list of audio it garbles the final audio ?

  6 février 2020, par Marie

  After several hours I have narrowed down the issue with the garbled audio to be the 2-seconds silence audio mp3 I am appending (I think I had produced it once with Wavelab)

  However, I tried using ffmpeg according to a post to produce a similar 2 seconds audio but it too will corrupt/garble/chop voice in the final concatenation of audio files.

  ffmpeg -f lavfi -i anullsrc=r=44100:cl=mono -t 2 -q:a 9 -acodec libmp3lame SILENCE_2sec.MP3

  I typically will have several audio files to concatenate together but for simplicity I have able to narrow it to a couple of files simplifying to the following script. A simple Windows batch file you should be able to use and reproduce the issue at your end.

  rem 
  
  rem  
  
  SET EXE="S:\_BINS\FFmpeg 4.2.1 20200112\bin\ffmpeg.exe"
  
  
  
  SET ROOTPATH=.\
  
  
  
  SET IN_FILE="%ROOTPATH%MyList.txt"
  
  
  
  ECHO file '%ROOTPATH%HELLO.mp3' > MyList.txt
  
  ECHO file 'SILENCE_2sec.MP3' >> MyList.txt
  
  
  
  SET OPTIONS= -f concat -safe 0 -i  %IN_FILE%  -c copy -y
  
  
  
  SET OUT_FILE="%ROOTPATH%CONCATENATED_AUDIO_2.MP3"
  
  
  
  SET INFO_FILE="INFO.TXT"
  
  
  
  %EXE% %OPTIONS%  %OUT_FILE% 1> %INFO_FILE% 2>&1 
  
  
  
  ECHO ======================== >> %INFO_FILE%
  
  ECHO IN_FILE=%IN_FILE%  >> %INFO_FILE% 
  
  ECHO EXE=%EXE%  >> %INFO_FILE% 
  
  ECHO OPTIONS=%OPTIONS%  >> %INFO_FILE% 
  
  ECHO ======================== >> %INFO_FILE%

  Here is the console info output from the ffmpeg, let me know if you need other output include ones from ffprobe

  ffmpeg version git-2020-01-10-3d894db Copyright (c) 2000-2020 the FFmpeg developers
  
    built with gcc 9.2.1 (GCC) 20191125
  
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  
    libavutil      56. 38.100 / 56. 38.100
  
    libavcodec     58. 65.103 / 58. 65.103
  
    libavformat    58. 35.101 / 58. 35.101
  
    libavdevice    58.  9.103 / 58.  9.103
  
    libavfilter     7. 70.101 /  7. 70.101
  
    libswscale      5.  6.100 /  5.  6.100
  
    libswresample   3.  6.100 /  3.  6.100
  
    libpostproc    55.  6.100 / 55.  6.100
  
  [mp3 @ 000000000036af80] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, concat, from '.\MyList.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 32 kb/s
  
      Stream #0:0: Audio: mp3, 24000 Hz, mono, fltp, 32 kb/s
  
  Output #0, mp3, to '.\CONCATENATED_AUDIO_2.MP3':
  
    Metadata:
  
      TSSE            : Lavf58.35.101
  
      Stream #0:0: Audio: mp3, 24000 Hz, mono, fltp, 32 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [mp3 @ 0000000000372d00] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 17280 >= 17255
  
  size=      11kB time=00:00:02.73 bitrate=  33.2kbits/s speed=2.73e+03x    
  
  video:0kB audio:11kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.137446%
  
  ======================== 
  
  IN_FILE=".\MyList.txt"   
  
  EXE="S:\_BINS\FFmpeg 4.2.1 20200112\bin\ffmpeg.exe"   
  
  OPTIONS= -f concat -safe 0 -i  ".\MyList.txt"  -c copy -y   
  
  ========================  

  I believe I am running FFmpeg 4.2.1, recently installed (20200112)

  You may produce the HELLO.mp3 by saving the following link

  https://translate.google.com.vn/translate_tts?en=UTF-8&q=Hello+&tl=en&client=tw-ob

  FYI, I am still a novice of ffmpeg and using it more like a black box with the help I received in this very super forum.
  Please be as explicit as you can with command line options on how I can fix this issue.
  Thank you.

  Additional Hints Debugging :

  If I append more files after the silence audio it seems that the silence audio impacts (garbles, chops) the previous audio.
  You may try the following for the list of audio files input.

  ECHO file '%ROOTPATH%HELLO.mp3' > MyList.txt
  
  ECHO file 'SILENCE_2sec.MP3' >> MyList.txt
  
  ECHO file '%ROOTPATH%HELLO.mp3' >> MyList.txt
  
  ECHO file '%ROOTPATH%HELLO.mp3' >> MyList.txt

  I typically add one or more silence file to derive a post silence effect after the actual audio. That’s my current logic. However if you have an alternative to appending a silence in the process of concatenating several audio files or appending x-seconds silence to an existing audio file. I can use that method as well from my coding.

  Thank you.

• What is the difference between raw MediaCodec implementation with FFmpeg integrated MediaCodec ?

  30 avril 2022, par Michael

  I google around the sample code for MediaCodec and notice there are three kinds of implementation in the market :

  


  

  1. Java version

  


  2. NDK version with raw MediaCodec API

  


  3. NDK version but FFmpeg takes care of everything

  


  


  I guess Java version is different on the performance side and use less frequently, but 2 & 3 are very confusing.

  


  If choose option 3, the work is easier and a noticeable change from SW decoding would be avcodec_find_decoder_by_name("h264_mediacodec"), and the implementation can easily share with iOS VideoToolBox.

  


  My question is would it be any performance or device compatible drawbacks compared with raw MediaCodec API ? Why did someone choose to use raw MediaCodec API ?

  


  Plus what if I use surface mode ?

  


• Precompiled FFmpeg for android versus building FFmpeg using android NDK

  19 juin 2017, par App Developer

  I am building an android app which does some video processing.

  I am currently using precompiled FFmpeg from https://github.com/writingminds/ffmpeg-android. The other option is to download FFmpeg source code and compile it using Android NDK. The reason I am contemplating option 2 is to enhance performance. My questions are

  1. Is there a difference between the two options mentioned above ?

  2. If yes, what would be the difference. Would it be enhanced performance (or) the result would simply be the same (or) are there some other benefits or drawbacks ?

  3. When they state precompiled FFmpeg, does it mean it was compiled using Android NDK for a specific architecture ?

  Please let me know.

  Thank you in advance !!!