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• How to get rec script of SOX to work on Android ?

  1er mai 2013, par Arif Nadeem

  I built sox for Android and I am using the generated binary files i.e. sox, rec, play and soxi generated directly in my app by installing them as binaries within my app.

  I am able to invoke commands using sox directly however I have a problem in invoking rec command.

  I used the following command, rec -r 8000 -c 2 output.wav
  But it fails saying that sox is not found or sox is expected but is not found.

  The above rec command works perfectly in Ubuntu when I use it in command line

  Please note that I am able to use operation related to sox binary successfully, but I am unable to use commands related to rec binary.

  Initially I thought the problem may be because of permissions imposed by Android so I included these permissions in manifest.xml but to no avail.

  I did some research and got this link, it says in section Using Sox to Play and Record that there might be some Linux systems which do not accept rec command directly.

  I followed his suggestion and appended my commands with padsp etc, but it still doesn't work.

  So my question is how do I invoke rec command successfully on Android system, has anyone tried this before ?

• Trim with ffmpeg without re-encoding gives issues on the trimming point

  3 mai 2022, par Oleg Merkulov

  I have a video file with following parameters :

  


  Container: mp4
Video: h264
Audio: AAC
Duration: 00:29:38.03


  


  I need to extract 2 parts from it and merge it into one video. I want to keep the quality and make the operation as fast as possible. Thus -> I don't want to re-encode.

  


  I'm using the following :

  


  ffmpeg -y -ss 00:01:00 -to 00:03:00 -i 30.mp4 -c copy part-1.mp4
ffmpeg -y -ss 00:21:00 -to 00:29:00 -i 30.mp4 -c copy part-2.mp4
ffmpeg -y -f concat -safe 0 -i parts.txt -c copy merged.mp4
parts.txt:
file 'part-1.mp4'
file 'part-2.mp4'


  


  the output has 103 warnings like that :

  


  [mp4 @ 0x7fa91d707e40] Non-monotonous DTS in output stream 0:1; previous: 5759491, current: 5719904; changing to 5759492. This may result in incorrect timestamps in the output file.
[mp4 @ 0x7fa91d707e40] Non-monotonous DTS in output stream 0:0; previous: 3598631, current: 3574391; changing to 3598632. This may result in incorrect timestamps in the output file.


  


  merged.mp4 has an issue on 00:02:00, right after the cut.
The audio is not in sync with video for around 5 seconds and then after that it goes perfectly.

  


  What can cause such an issue ? Is there is a way to trim without losing quality ?

  


• Merge two audio files using ffmpeg : Unsafe file name './temp/speech/audio0.mp3'

  18 juillet 2022, par PixelPage

  i want to merge audio files (/temp/speech/audio.mp3) into one (/temp/audio.mp3). I already tried ffmpeg -f concat -i ./temp/speech/afiles.txt -c copy ./temp/audio.mp3 (I use nodejs child_process), but i get this error :

  


  [concat @ 0x7fc08f70f140] Unsafe file name './temp/speech/audio0.mp3'
./temp/speech/afiles.txt: Operation not permitted

at ChildProcess.exithandler (node:child_process:398:12)
at ChildProcess.emit (node:events:527:28)
at maybeClose (node:internal/child_process:1092:16)
at Process.ChildProcess._handle.onexit (node:internal/child_process:302:5)


  


  Note : This is my ./temp/speech/afiles.txt file :

  


  file './temp/speech/audio0.mp3'
file './temp/speech/audio1.mp3'
file './temp/speech/audio2.mp3'
file './temp/speech/audio3.mp3'
file './temp/speech/audio4.mp3'


  


  Thanks, Pixelpage