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• ffmpeg inconsistent speed results by version breaking large audio file into multiple pieces with -ss/-to positional parameters [closed]

  2 novembre 2024, par BenH

  I am trying to chop a large (12 hour+) audio file up into multiple segments using multiple -ss/-to positional operations.

  


  ffmpeg.exe -loglevel error -stats -i "C:\data\chapters\joined_output.mp3" -ss -1 -to 1159 -c copy "C:\data\chapters\001 - Chapter 1.mp3" -ss 1159 -to 1800 -c copy "C:\data\chapters\002 - Chapter 2.mp3" -ss 1800 -to 3181 -c copy "C:\data\chapters\003 - Chapter 3.mp3" ... output.mp3


  


  The '...' indicates that I have more than 20 of such repeated statements to break up into 20 or more chapter files.

  


  I arrived on this because using individual command were processing the entire file each time to parse out the section I wanted. I realize there is an option to place -ss/-to prior to the input file, and have since discovered that this appears to work quicker, but I have not found syntax to use this in a single command and therefore must create a separate command for each chapter.

  


  The above syntax appears to work fine, but was taking about 4 minutes to process. When I reverted to older versions this operation completes much quicker. About 20 seconds with version 6.1 and about 10 seconds on version 5.

  


  There is some discrepancy with how the old versions report the length of the file (it appears to show only about 6.5 hours processed in "out_time" value), but the resulting output files appear to be correct. I think it might be reporting out_time of only the longest section it is processing as the 6.5 hours appear to match the length of that output section.

  


  To be clear, version 5 using my above syntax appears to create all my output files correctly in 10 seconds.

  


  If I split them up into individual commands with -ss/-to before the input, then it actually takes longer with ffmpeg version 5/6 (about 45 seconds compared to 10-20 seconds).
With the latest version 7 it takes about 1 min, 15 secs. Much better than the 4 minutes using my syntax above but still well slower than using version 5/6 with that same syntax.

  


  So, in short, why am I able to (apparently) properly split this 12 hour file into about 25 different segments in about 10 seconds using the syntax above on version 5, but it takes 2x that long on 6, and 30x that long on 7 ? I assume there are just syntax changes I can't figure out or some changes to default behavior ?

  


• How to extract jpegs from a video file using ffmpeg [migrated]

  28 octobre 2013, par Andrew Simpson

  I am using C# and ffmpeg.

  In this scenario I have 279 individual jpegs and i have used ffmpeg to create a AVI file from these images on my client.

  CMD Line :

   -f image2 -r 10 -i "C:\000EC902F17F\img%05d.jpg"  -s 352x288  -y "C:\1\test.avi"

  I then upload to my server.

  CMD Line :

  -i c:\1\1.avi c:\1\img-%05d.jpg

  I then extract jpegs from the AVI file. I get 265 jpegs back.

  Obviously ffmpeg is dropping these frames (most probable) when the avi is 1st created. Is there a way to 'force' to encode using ALL the images I have ?

  Thanks.

  PS
  I did not specify any command line option other than the size of the video output. As far as I am aware if none are specified then ffmpeg automatically chooses the best ones ?

• Pipe ffmpeg stream to sox rec [closed]

  8 novembre 2023, par Red-Tune-84

  I am reading an audio stream via ffpmeg like this :

  



  ffmpeg -i http://icecast.radiovox.org:8000/live.ogg -f mp3 filename

  



  and want to pipe it to a sox command :

  



  rec filename rate 32k silence 1 0.1 3% 1 3.0 3%.

  



  Ultimately, what I am trying to achieve, is to record the audio from a live Icecast stream of a talk show. I only want recordings though of the individual's speaking. Everytime there is silence, I want to stop the recording and start a new one once they start speaking again.