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• Java : How to merge and cut H.264 mp4 files with ffmpeg

  15 novembre 2016, par Nico

  I wrote an java application to handle my GoPro video data. Recording for a couple of hours the GoPro produces several chapters (mp4-files). Now the program is able to cut out a sequence no matter if it is in just one chapter or it touches more. I execute the outstanding tool ffmpeg.exe with the Processbuilder.
  First the program exports the mp4-files to *.ts-files and then it merges it togehter to one only mp4-file. At least a sequence will be cut out of this merged mp4-file using ffmpeg.exe for the second time. It works quite reliable and quickly.

  But : I do not have one application in its entirely, but also I have two files (jar-Application and ffmpeg.exe). I think there is are java-libraries of ffmpeg but I do not know how to include and how to use them. I am just searching for a one-file-solution.

  Do you know which library I need and where I can download it ? How may I have to use it ? If that is not possible, do you know some other user-friendly libraries doing the same job with less lines of code ? How to use them ?

  I am very grateful about your help and the examples you will give !

• ffmpeg Muxing Recovered Files - Audio dropping

  7 avril 2020, par Chris McL

  A few years ago, we accidentally deleted all our home movies. We recovered the files from the camera. They have lost their headers and are not playable. I have used a recovery program (recover_mp4) to get an h264 and aac file.

  



  When I try to mux these together, the audio drops off from the stream. It also crackles badly at times. If I play the AAC file by itself, it sounds fine. For some movies, the audio works for a while, on others it drops out quickly.

  



  One thing I noticed is that the resulting muxed mp4 file is often shorter than the audio.

  



  I've tried various ffmpeg commands that look generally like this :

  



  ffmpeg -r 30000/1001 -i recovered_video.h264 -i recovered_audio -bsf:a aac_adtstoasc -c:v copy -c:a copy output.mp4

  



  Any ideas on how to marry the two files together ?

  


• using pocketsphinx_continuous with a .wav file

  3 avril 2013, par user2242131

  I am attempting to write an application that will allow a user to speak a small set of commands from a remote system and have them executed on my server. Using pocketsphinx to parse the spoken text. When run locally with the microphone, pocketsphinx_continuous works perfectly no matter how I slur the words. But when importing the audio file and using ffmpeg to downsample the audio to a single channel, 16 bit PCM file, it will parse the first word without difficulty. Then it will skip everything else and treat it as . I am confident that the problem is in the file format and not in the pocketsphinx configuration.

  Using command line
  ffmpeg -y -i Sound\AddSheet.wav -ac 1 -f s16le -acodec pcm_s16le -ar 16k AddTmp.wav
  in a batch file.

  The bottom of the output I get is :

  INFO: fsg_search.c(1407): Start node ADD.0:5:47
  
  INFO: fsg_search.c(1407): Start node <sil>.0:2:49
  
  INFO: fsg_search.c(1446): End node <sil>.126:128:305 (-486)
  
  INFO: fsg_search.c(1662): lattice start node <s>.0 end node <sil>.126
  
  INFO: ps_lattice.c(1352): Normalizer P(O) = alpha(<sil>:126:305) = -175371
  
  INFO: ps_lattice.c(1390): Joint P(O,S) = -176076 P(S|O) = -705
  
  000000000: ADD USER
  
  </sil></sil></s></sil></sil>

  Which is not the audio in the file. The words spoken in the file are "ADD SPREADSHEET", which works perfectly from the same microphone without the intervening .wav file.

  I have tried increasing the audio volume and decreasing the background noise using sox :

  sox -v 3.0 Sound\%1 Sound\%1-loud.wav ffmpeg -i Sound\%1-loud.wav -vn -ss 00:00:00 -t 00:00:01 -y Sound\%1-noiseaud.wav 
  
  sox Sound\%1-noiseaud.wav -n noiseprof Sound\%1-noise.prof 
  
  sox Sound\%1 Sound\%1-clean.wav noisered sound\noise.prof 0.21 
  
  ffmpeg -y -i Sound\%1-clean.wav -ac 1 -f s16le -acodec pcm_s16le -ar 16k AddTmp.wav

  with no noticeable effect on the final results.

  If you look at the output you will notice that fsg_search.c has found ADD as the start node, then silence for the remainder. Please help on this.