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• How convert High bitrate mp3 to lower rate using ffmpeg in android

  23 mars 2018, par Android Team

  We want to convert 320kbps mp3 file to 128kbps mp3 so currently we are using below ffmpeg command but its not working.

  ffmpeg -i input.mp3 -codec:a libmp3lame -qscale:a 5 output.mp3

  Result :-the output bitrate same as input mp3.

  And we are following the FFmpeg Encoding guideline for that here is the link :- https://trac.ffmpeg.org/wiki/Encode/MP3

  so please suggest any solution.

• ffmpeg clean all noise background silences in a poscast

  23 mars 2019, par fireDevelop.com

  I have hundreds of podcast without music, just the voice and the room silence.
  In the silences, I have many clicks, respirations, etc...
  I need to clean all silences with a script, keeping intact the voice.

  In this picture you can see my dirty silences

  And here the result I want in all my audios

  When I use some scripts of sox. I don`t get the result I spect because the voice is affected by the script, the room-silence disappear and some clic still in the silences.

  Then in order to keep intact the voice, I want to do this :

  1. Delete all the silences longer than 3 seconds.

  ---

  2. Split all the audio and silences with in a sequence numbers. ie. :

     • 001-Silence-2.0seconds.wav
     • 002-voice.wav
     • 003-Silence-0.25seconds.wav
     • 004-voice.wav
     • 005-Silence-0.75seconds.wav
     • 006-voice.wav
     • ...
     • ...

  ---

  3. Before, run the script I created manually many files with silences of diferents silences I will use :

     • myManuallySilence-0.25seconds.wav
     • myManuallySilence-0.50seconds.wav
     • myManuallySilence-0.75seconds.wav
     • myManuallySilence-0.1seconds.wav
     • myManuallySilence-1.25seconds.wav
     • ...
     • ...
     • myManuallySilence-2.50seconds.wav
     • myManuallySilence-2.75seconds.wav
     • myManuallySilence-3.0seconds.wav

  ---

  4. the script will check the dirty silences duration and replace by the files myManuallySilence-x.xseconds.wav

  ---

  5. merge all files in one wav file, with the original voice and all the silences cleanned.

  ---

  At the moment I have only this script :

  # get the path of Adobe Audition and add timestamp in the output 
  
  filename
  
  fileName=out
  
  current_time=$(date "+%Y.%m.%d-%H.%M.%S")
  
  newFileName=$fileName.$current_time.wav
  
  #yourPathAPP=/Applications/Adobe\ Audition\ CC\ 2019/Adobe\ Audition\ 
  
  CC\ 2019.app
  
  yourPathAPP=/Volumes/6TB/Applications/ocenaudio.app
  
  # # First denoise audio
  
  
  
  # ## Get noise sample
  
   ffmpeg -i in.wav -vn -ss 00:00:00 -t 00:00:01 noise-sample.wav
  
  
  
  # ## Create noise profile
  
   sox noise-sample.wav -n noiseprof noise.prof
  
  
  
  # ## Clean audio from noise
  
   sox in.wav $newFileName noisered noise.prof 0.50
  
  # # Split audio by noise
  
   sox -V3 $newFileName output.wav silence 1 00:00:02.000 - 80d 1 
  
   00:00:02.000 -80d : newfile : restart
  
  
  
  # ####### (these settings worked for my computer mic - maybe we need to 
  
  finetune them later) #######

  Is getting all the voice in separate files like this :
  output001.wav
  output002.wav
  output003.wav
  output004.wav
  ...
  output00x.wav

  Please, any suggestion will be appreciated.
  Thanks so much in advance !

• How to save ffmpeg segmets to disk immediately with sub-second intervals ?

  20 octobre 2023, par amfast

  I'm trying to record video on a raspberry and have it save as much as possible (sub-second resolution) in case of a power cutoff.

  


  I use -f segment to save the encoded stream in 100ms segments with the hope that all but the interrupted (by power cutoff) segment will be saved in memory. Unfortunately, when cutting off power, all the destination files (output_0001.mp4, output_0002.mp4, ...) are created, but empty.

  


  To save the files to disk immediately, I added the -strftime 1 option that allows formatting the output filename as time. It seems weird that this is the (only ?) way to trigger immediate saving of files, but it works - untill I try to have segments smaller than 1 second. The problem seems to be that the format string %d, that previously added a sequence number in my output filenames, now represents "day" (i.e. date) and the smallest resolution time format string is %S for second. I saw %f suggested somewhere for smaller resolutions, but it only prints "%f".

  


  The result is that the segmentation part of ffmpeg does create 100ms segments and save them to disk immediately, but the strftime feature gives the output files names that only change every second, so all the interim files are overwritten.

  


  Example of the failing command below. Without the -strftime option this creates nice segments, but does not save them to disk immediately.

  


  libcamera-vid --flush \
    --framerate ${FRAMERATE} \
    --width ${WIDTH} \
    --height ${HEIGHT} \
    -n \
    -t ${TIMEOUT} \
    --codec yuv420 \
    -o - | 
ffmpeg \
    -fflags nobuffer \
    -strict experimental \
    -loglevel debug \
    -flags low_delay \
    -f rawvideo \
    -pix_fmt yuv420p \
    -s:v ${WIDTH}x${HEIGHT} \
    -r ${FRAMERATE} \
    -i - \
    -c:v h264_v4l2m2m \
    -f segment \
    -segment_time 0.1 \
    -segment_format mp4 \
    -reset_timestamps 1 \
    -strftime 1 \
    -b:v ${ENCODING_BITRATE} \
    -g 1 \
    "output_%04d.mp4"


  


  Question :
  
Is there another way besides -strftime to trigger immediate saving ? Or is there a mechanism to feed finer resolution format strings to the output filename ?