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• VLC - Transcoding a 4k Picture to a Transport Stream

  20 janvier 2020, par gdogg371

  After a lot of crying, stamping my feet and pulling my hair out, I have now managed to transcode my 4k capture card into an RTP MPEG2 transport stream using VLC, as per the below :

  vlc dshow:// :dshow-vdev="Video (00 Pro Capture HDMI 4K+)" :dshow-adev="Audio (2- 00 Pro Capture HDMI 4K+)" :dshow-threads=8 :dshow-aspect-ratio=16\:9 :dshow-size="2160x1080" :dshow-pixel_format=NV12 :dshow-tune=film :dshow-preset=veryslow :dshow-vcodec=hevc_nvenc :dshow-fps=50 :dshow-crf=0 :dshow-acodec=mp4a :dshow-stereo-mode=5 :dshow-force-surround-sound=0 :dshow-ab=128 :dshow-samplerate=44100 :no-dshow-config :live-caching=100 :sout=#transcode{venc=ffmpeg,vcodec=mp2v,threads=8,aspect=16:9,width=2160,height=1080,fps=50,aenc=ffmpeg,acodec=a52,ab=1500,channels=6,samplerate=48000,soverlay}:rtp{dst=192.168.1.15,port=8554,mux=ts}

  My remaining issue though is, that I cannot get a 4k picture to transcode cleanly. I get horrendous stutter of the picture if I try and 2160x1080 at 50 fps is the best I have been able to achieve.

  The Magewell 4k card I have been using runs natively at 3840x2160 at 50fps, outputting a raw video signal. Is there some kind of built in limitation of MPEG2 where it cannot handle a 4k signal that I am not aware of ?

  Can anyone suggests some amendments to the above, so as to process a 4k signal properly ?

  Thanks

• FFMPEG mp4 videos not suddenly stops playing on Browsers

  14 janvier 2020, par Harley Lapuz

  I have been struggling with this issue in regards to playing my converted mp4 videos using FFMPEG into an html 5 video player, I basically just use a single video player and just replace the source when the video ends.

  What happens is that a MediaError occurs randomly with different videos saying :

  PIPELINE_ERROR_DECODE: Failed to send audio packet for decoding

  or

  PIPELINE_ERROR_DECODE: audio decode error

  Videos have no issues on Safari, Internet Explorer, and Firefox. But this error shows up randomly on Opera and Google Chrome.

  I am using Laravel [Laravel FFMpeg][1] to convert the videos, please see my conversion code below :

  $bitrateFormat = (new FFMpeg\Format\Video\X264('aac', 'libx264'))->setKiloBitrate(1500);
  
  
  
  $converted_video = FFMpeg::fromDisk('videos')
  
      ->open($this->video_id)
  
      ->addFilter(['-pix_fmt', 'yuv420p'], ['-movflags', '+faststart'])
  
      ->export()
  
      ->inFormat($bitrateFormat)
  
      ->toDisk('do_spaces_video')
  
      ->save($this->video_id);

  Any help would be appreciated guys, thanks in advance !

  EDIT - Added Media Internals Error

  00:04:02.892    for_suspended_start false
  
  00:04:02.892    pipeline_buffering_state    BUFFERING_HAVE_ENOUGH
  
  00:04:33.919    error   Failed to send audio packet for decoding: timestamp=272341333 duration=21333 size=346 side_data_size=0 is_key_frame=1 encrypted=0 discard_padding (us)=(0, 0)
  
  00:04:33.919    error   audio decode error
  
  00:04:33.943    error   audio error during playing, status: PIPELINE_ERROR_DECODE
  
  00:04:33.943    pipeline_error  PIPELINE_ERROR_DECODE
  
  00:04:33.944    pipeline_state  kStopping
  
  00:04:33.945    pipeline_state  kStopped
  
  00:04:33.950    event   PAUSE

• Batch merge audio files by specific timestamp without reencoding

  8 mai, par Saccarab

  I want to batch merge mp3 audio files where every single file has a specific start time. So below is the fluent-ffmpeg spawn I use right now to merge 3 files with each starting at respectively 200, 7400 and 10600.

  



  ffmpeg -i firstFile.mp3 -i secondFile.mp3 -i thirdFile.mp3 -filter_complex 
[0]adelay=200[a0];[1]adelay=7400[a1];[2]adelay=10600[a2];[a0][a1] 
[a2]amix=inputs=3:dropout_transition=1000,volume=3 -f mp3 pipe:1


  



  This works pretty good, except for longer files re-encoding makes the process take real long. So I wanted to do the same thing using concat demuxer. Since I already know how long each audio file is, I've put in silent audio files between them to create a delay until next audio file so it actually starts on the time position it is supposed to.

  



  #concatfile.txt

file silence.mp3
outpoint 200
file firstFile.mp3
file silence.mp3
outpoint 1500
file secondFile.mp3
file silence.mp3
outpoint 2000
file thirdFile.mp3

ffmpeg -f concat -safe 0 -i concatfile.txt -c copy output.mp3


  



  This solution also works okay when merging few files but when I merge higher count of files like 30 or 40 result file will have a slowly increasing synchronization problem where audio files actually start later than the start timestamps they are supposed to have.

  



  Looks like an issue similar to this post

  



  I'm open for any suggestion on solving the issue.