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• ffmpeg : Apply a time-based expr to control intensity of lowpass, highpass, aphaser, or aecho [closed]

  17 mai 2024, par Wes Modes

  I am procedurally constructing complexFilters for ffmpeg via fluent-ffmpeg. My fluent-ffmpeg complex filters look like :

  


  {
   "filter": "volume",
   "options": {
       "volume": "min(1, max(0, ((cos(PI * t * 1 / 13) * 1 + cos(PI * t * 1 / 7) * 0.5 + cos(PI * t * 1 / 3) * 0.25) +
-0.5 ) * 0.75 * -1 + 0.5))",
       "eval": "frame"
    },
    "inputs": "track_1_output",
    "outputs": "track_1_adjusted"
},


  


  Note that I am using an expression to determine the volume dynamically.

  


  Here I'm testing on the command line, to understand the mysteries of lightly-documented ffmpeg filters. I'm fading in and out two sources, intertwined in the output. Now I want to apply lowpass, highpass, aphaser, and/or aecho to the transitions using a time-based expr.

  


  I've already succeeded using the volume filter to fade the sources in and out (Note that the sine has reversed polarity for the second volume filter) :

  


  # working fade in/out
ffmpeg -i knox.mp3 -i static.mp3 -filter_complex \
"[0:a] \
    volume = 'min(1, max(0, 0.5 + 0.5 * cos(PI * t / 5)))': eval=frame \
    [a0]; \
[1:a] \
    volume = 'min(1, max(0, 0.5 - 0.5 * cos(PI * t / 5)))': eval=frame \
    [a1]; \
[a0][a1]
    amix = inputs=2: duration=shortest" \
-c:a libmp3lame -q:a 2 output.mp3


  


  ffmpeg -filters says that lowpass has time-based support :

  


    T.. = Timeline support
 TSC lowpass           A->A       Apply a low-pass filter with 3dB point frequency.


  


  How can I similarly apply these other filters to source1 using a time-bassed expr ? I was unsuccessful in figuring out lowpass and highpass :

  


  # applying a lowpass filter
ffmpeg -i knox.mp3 -i static.mp3 -filter_complex \
"[0:a] \
    volume = 'min(1, max(0, 0.5 + 0.5 * cos(PI * t / 5)))': eval=frame, \
    lowpass=f=3000: mix='0.5 + 0.5 * cos(PI * t / 5)' \
    [a0]; \
[1:a] \
    volume = 'min(1, max(0, 0.5 - 0.5 * cos(PI * t / 5)))': eval=frame \
    [a1]; \
[a0][a1]
    amix = inputs=2: duration=shortest" \
-c:a libmp3lame -q:a 2 output.mp3


  


  With the resultant error :

  


  [Parsed_lowpass_1 @ 0x7f9a72005c00] [Eval @ 0x7ff7bec423d8] Undefined constant or missing '(' in 't/5)'
[Parsed_lowpass_1 @ 0x7f9a72005c00] Unable to parse option value "0.5 + 0.5 * cos(PI * t / 5)"
Error applying option 'mix' to filter 'lowpass': Invalid argument


  


  What complicated fffmpeg faerie magic is needed to make some of the filters other than volume controlled by a time-based expr ?

  


• movenc : Set the last packet duration based on the next packet when autoflushing

  9 mars 2015, par Martin Storsjö

  movenc : Set the last packet duration based on the next packet when autoflushing
  When automatically flushing fragments based on set conditions
  
  (fragmentation on keyframes, after some interval or byte size),
  
  we already have the next packet for one stream - use this for setting
  
  the duration of the last packet in the flushed fragment correctly.
  This avoids having to adjust the timestamp of the first packet in
  
  the new fragment since the last duration was unknown.
  Unfortunately, this only works for automatic flushing (not for
  
  caller-triggered flushing, like in the dash muxer), and only for the
  
  one single track that triggered the flushing. The duration of the
  
  last sample in all other tracks still is dependent on AVPacket
  
  duration (or heuristics).
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/movenc.c

• Revision ac53c41e64 : Merge "Tile based adaptive mode search in RD loop"

  25 octobre 2014, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_encoder.c

  
   Modify /vp9/encoder/vp9_encoder.h

  
  
  Merge "Tile based adaptive mode search in RD loop"