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• Changing video frame rate and keeping duration intact

  6 mai 2018, par Idan

  I am trying to segment a video file, transcode each of the segments and then stitch them all back to one. The process is working but I have noticed that the final file has a different duration than the original one. Probably because I am transcoding to a fixed frame rate which is different from the source frame rate.

  To segment the video I use :

  ffmpeg -y -i video_only.mp4 -c copy -flags -global_header -segment_time 50 -break_non_keyframes 0 -reset_timestamps 0 \
  
    -segment_list file_segs.list -segment_format mp4 -segment_list_type ffconcat -write_empty_segments 0 \
  
    -f segment file_seg-%d.mp4

  Then, each segment is transcoded with this command :

  ffmpeg -y -i $f -vcodec libx264 -vsync 1 -crf 18 -vf "fps=30" -pix_fmt yuv420p -preset:v fast -profile:v main -level:v 4.1 transcoded/$f

  And finally, concat :

  ffmpeg -y -f concat -i file_segs.list -c:v copy -c:a copy -movflags +faststart video_final.mp4

  I’ve tried using "-r 30" instead on the filter (-vf), the same result.
  As this is a part of a transcoding system I prefer not to check for the input file fps before transcoding as it can be anything - variable fps too (which is not so easy to detect)

  Is there any way I can keep the duration intact while changing the frame rate in this type of transcoding flow ?

• FFMPEG mixing .wav files volume control [closed]

  1er avril 2024, par JoonSeo Yang

  I am working on Java, using the ffmpeg library with command line processing to mix 2 .wav files into one .wav file, but I would like to know how to control the volume of each original file.

  


  My problem : i have 2 audio files (human voice BGM), but BGM is too loud, so i can barely hear human voice, i would like to -> volume down the BGM file, or volume up voice file

  


  Here is my partial code

  


  String ffmpegCommand = file_exe.getAbsolutePath()
    + String.format(
        " -i %s -i %s -filter_complex amix=inputs=2:duration=first:dropout_transition=3 %s",
        file_1.getAbsolutePath(), file_2.getAbsolutePath(), outputFilePath);
Process process = Runtime.getRuntime().exec(ffmpegCommand);


  


  it is quite simple code. I need help on this, and it would be very thankful to which document to read to get such information

  


  PS.sorry for my poor eng.. Im not native :D

  


  I was wandering around documentations, but its quite hard to find what i want

  


• Revision 5e766ccee0 : Use rate/distortion thresholds to control non-RD partition search Compare the e

  15 octobre 2014, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_speed_features.c

  
  
  Use rate/distortion thresholds to control non-RD partition search

  Compare the estimated rate and distortion to the thresholds scaled
  according to the operating block size and determine if further
  split partition search will be run. The compression performance of
  speed -5 is changed by -0.074%. The encoding speed is 10% - 15%
  faster.

  vidyo1 720p
  16545 b/f, 40.492 dB, 11475 ms -> 16535 b/f, 40.486 dB, 10100 ms

  nik720p
  16624 b/f, 36.310 dB, 10071 ms -> 16617 b/f, 36.313 dB, 8346 ms

  Change-Id : Ic9197ab5761279ae55d2fb7813b2af0e0db497b8