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• avcodec/encode, frame_thread_encoder : Unify calling encode callback

  23 août 2022, par Andreas Rheinhardt

  avcodec/encode, frame_thread_encoder : Unify calling encode callback
  The encode-callback (the callback used by the FF_CODEC_CB_TYPE_ENCODE
  
  encoders) is currently called in two places : encode_simple_internal()
  
  and by the worker threads of frame-threaded encoders.
  After the call, some packet properties are set based upon
  
  the corresponding AVFrame properties and the packet is made
  
  refcounted if it isn't already. So there is some code duplication.
  There was also non-duplicated code in encode_simple_internal()
  
  which is executed even when using frame-threading. This included
  
  an emms_c() (which is needed for frame-threading, too, if it is
  
  needed for the single-threaded case, because there are allocations
  
  (via av_packet_make_refcounted()) immediately after returning
  
  from the encode-callback).
  Furthermore, some further properties are only set in
  
  encode_simple_internal() : For audio, pts and duration are derived
  
  from the corresponding fields of the frame if the encoder does not
  
  have the AV_CODEC_CAP_DELAY set. Yet this is wrong for frame-threaded
  
  encoders, because frame-threading always introduces delay regardless
  
  of whether the underlying codec has said cap. This only worked because
  
  there are no frame-threaded audio encoders.
  This commit fixes the code duplication and the above issue by factoring
  
  this code out and reusing it in both places. It would work in case
  
  of audio codecs with frame-threading, because now the values are
  
  derived from the correct AVFrame.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/encode.c
  • [DH] libavcodec/encode.h
  • [DH] libavcodec/frame_thread_encoder.c

• insert audio into another audio file (eg a censor bleep)

  3 avril 2019, par Redzarf

  I need to insert a short beep into another audio file (similar to a censorship bleep) using linux and/or php.

  I’m thinking there should be some way to do it with ffmpeg (with some combination of -t, concat, map, async, adelay, itsoffset ?) or avconv or mkvmerge - but haven’t found anyone doing this. Maybe I need to do it in 2 stages somehow ?

  For example if I have a 60 second mp3 and want to beep out 2 seconds at 2 places the desired result would be :

  0:00-0:15  from original
  
  0:15-0:17  beep (overwrites the 2 secs of original)
  
  0:17-0:40  from original
  
  0:40-0:42  beep
  
  0:42-0:60  from original

  I have a 2 second beep.mp3, but can use something else instead like -i "sine=frequency=1000:duration=2"

• ffmpeg render file with transparent background

  16 novembre 2022, par Валентин Никин

  I have the next scheme of tracks. I need to render that tracks to one track with ffmpeg.

  


  

  


  After rendering it's should looks like

  


  

  


  I want to use the next scheme :

  


  

  1. Rendering Track 001 to file.

  


  2. Rendering Track 002 to file.

  


  3. Overlay Track 002 on Track 001.

  


  


  For the "Track 001" I can "concat" clips to one track without any problem.

  


  But the question is how I should concat clips for the "Track 002" ? The "Empty" places must be transparent for the overlaying on the 3 step.

  


  I already tried to use for the Empty places input with transparent color. But on the overlaying step transparent doesn't work.

  


  ffmpeg -f lavfi -i color=c=red@0.0:s=1920x1080:r=25:d=1 \
    -i Clip004.mp4 \
    -i Rendered_track_001.mp4 \
    -filter_complex "[0:v] [1:v] xfade=transition=fade:duration=2:offset=0.5[trak]; \
                    [2:v][trak]overlay[out]" \
     -map "[out]" -c:v vp9 -c:a copy test.webm


  


  I also tried to use alphaextract and alphamerge like this

  


  ffmpeg -f lavfi -i color=c=red@0.0:s=1920x1080:r=25:d=1 \
    -i Clip004.mp4 \
    -i Rendered_track_001.mp4 \
    -filter_complex "[0:v] [1:v] xfade=transition=fade:duration=2:offset=0.5[out]; \
                    [out]alphaextract[alpha];[2:v][alpha]alphamerge[out1]" \
     -map "[out1]" -c:v vp9 -c:a copy test.webm


  


  But it's fail with error

  


  [AVFilterGraph @ 0x556557d3ce00] The following filters could not choose their formats: 
Parsed_alphaextract_1
Consider inserting the (a)format filter near their input or output.
Error reinitializing filters!
Failed to inject frame into filter network: Input/output error
Error while processing the decoded data for stream #2:0


  


  Any help would be appreciated.