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• ffmpeg : How to concat audio files and add background music in a single command ?

  1er mai 2018, par harishkumar329

  Need to concat audio files and add background music in a single command.

  Right now I use the following commands to do so,

  To concat :

  ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 -i 4.mp4 -i 5.mp4 -i 6.mp4 -i 7.mp4 -i 8.mp4 -i 9.mp4 -i 10.mp4  -filter_complex '[0:0][1:0]concat=n=10:v=0:a=1[out]'  -map '[out]' -strict -2 -y 10_final.mp4

  To add background music :

  ffmpeg -i 10_final.mp4 -i music.mp4 -filter_complex "[0:a]volume=1dB[a0];[1:a]volume=0.5[a1];[a0][a1]amerge=inputs=2[a]" -map "[a]" -ac 1 -ab 32000 -ar 22050 -strict -2 -y 10_with_music.mp4

  But his process is a quite time-consuming process as every time the file read/write happening to the output.

  Is there a way I can merge these two above commands to a single so that the command should be optimized.

• Fix "Non-monotonic DTS" Warning Caused By asetnsamples Filter

  3 septembre 2024, par Harry Muscle

  I'm using the following complex filter to mute certain parts of an audio file and replace those parts with a beep generated by the sine filter :

  


  [0]asetnsamples=n=1,volume=0:enable='between(t,1.57,1.97)+between(t,4.77,5.27)+between(t,5.37,5.87)+between(t,6.37,6.77)'[dippedVocals];sine=d=10:f=1000:samples_per_frame=1,pan=stereo|FL=c0|FR=c0[constantBleep];[constantBleep]atrim=start=0:end=6.77[shortenedBleep];[shortenedBleep]volume=0:enable='between(t,0,1.57)+between(t,1.97,4.77)+between(t,5.27,5.37)+between(t,5.87,6.37)'[dippedBleep];[dippedVocals][dippedBleep]amix=inputs=2


  


  Since I need the locations specified to be exact I'm using the asetnsamples filter to set 1 sample per frame to get the highest possible accuracy. However, as soon as I add this asetnsamples filter to my filter chain I get thousands of these messages :

  


  Non-monotonic DTS; previous: XXX, current: XXX; changing to XXX.  This may result in incorrect timestamps in the output file.


  


  Any idea what's causing that and how to fix it ? BTW, the input file is a ogg file encoded at 44100Hz and the output file is a wav file. Do wav files even contain timestamps ?

  


• playing, decoding, seeking, audio from command line

  25 août 2017, par AbstractDissonance

  There are various way to use audio, I would like to find several different audio players that can do the following easily, from the command line :

  1. Carry out the standard audio function : Play, pause, stop, seek(absolute), volume(absolute), mute.

  2. Be able to decode and get the raw data of the audio input so one can display a waveform.

  — Correct answers will provide the player, the command line to do the functions and/or how one can interact with it programmatically if necessary.

  e.g.,

  Program : FFmpeg
  decode : pipe out using -i <filename> -f s16le -ac 1 -</filename>
  play : ffplay -nodisp then send keys to wmproc(keys don’t work without window open and -nodisp closes window, so much wm the keys)
  stop, pause, etc are the same. Does not have a way to absolutely seek or set volume.

  Other programs might be vlc, etc.

  The reason I am asking this is because I would like to provide several options for my program to use what the user might already have without having to require shipping or downloading dlls(i.e., hard dependencies).

  Bonus points for being able to control pitch and speed.