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• Concat creates a still image before the video

  7 décembre 2017, par Vitalis Hommel

  I am creating a cutlist like this

  file 't1.MP4'
  
  inpoint 1.45067
  
  outpoint 3.18133
  
  file 't2.MP4'
  
  inpoint 3.45067
  
  outpoint 6.18133
  
  ...

  and I use it like this

  ffmpeg -y -f concat -safe 0 -i list.txt -c:v libx264 -c:a aac -af aresample=async=1 -pix_fmt yuv420p output.mp4

  The output almost always contains a still image at the start, sometimes half the video time, sometimes less, showing the first frame then the final video starts. I noticed, the less inpoint and outpoint are apart, the longer the still image at the start. Maybe its also connected to the amount of inpoint and outpoint.

  How do I solve this ?

• Revision effd974b16 : Limit arf interval for low fpf clips. This patch limits the maximum arf interv

  16 avril 2015, par paulwilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_ratectrl.c

  
  
  Limit arf interval for low fpf clips.

  This patch limits the maximum arf interval length to
  approximately half a second. In some low fps animations in
  particular the existing code was selecting an overly long interval
  which was hurting visual quality. For a sample problem test clip
  (360P animation , 15fps, 200Kbit/s) this change also improved
  metrics by >0.5 db.

  There may be some clips where this hurts metrics a little, but the
  worst case impact visually is likely to be less than having an
  interval that is much too long. On more normal material at 24
  fps or higher, the impact is likely to be nil/minimal.

  Change-Id : Id8b57413931a670c861213ea91d7cc596375a297

• Xuggler encoding and muxing

  18 décembre 2012, par HeineyBehinds

  I'm trying to use Xuggler (which I believe uses ffmpeg under the hood) to do the following :

  • Accept a raw MPJPEG video bitstream (from a small TTL serial camera) and encode/transcode it to h.264 ; and
  • Accept a raw audio bitsream (from a microphone) and encode it to AAC ; then
  • Mux the two (audio and video) bitsreams together into a MPEG-TS container

  I've watched/read some of their excellent tutorials, and so far here's what I've got :

  // I'll worry about implementing this functionality later, but
  
  // involves querying native device drivers.
  
  byte[] nextMjpeg = getNextMjpegFromSerialPort();
  
  
  
  // I'll also worry about implementing this functionality as well;
  
  // I'm simply providing these for thoroughness.
  
  BufferedImage mjpeg = MjpegFactory.newMjpeg(nextMjpeg);
  
  
  
  // Specify a h.264 video stream (how?)
  
  String h264Stream = "???";
  
  
  
  IMediaWriter writer = ToolFactory.makeWriter(h264Stream);
  
  writer.addVideoStream(0, 0, ICodec.ID.CODEC_ID_H264);
  
  writer.encodeVideo(0, mjpeg);

  For one, I think I'm close here, but it's still not correct ; and I've only gotten this far by reading the video code examples (not the audio - I can't find any good audio examples).

  Literally, I'll be getting byte-level access to the raw video and audio feeds coming into my Xuggler implementation. But for the life of me I can't figure out how to get them into an h.264/AAC/MPEG-TS format. Thanks in advance for any help here.