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• Convert image sequence to video using ffmpeg and list of files

  13 mai 2015, par rensa

  I have a camera taking time-lapse shots every 2–3 seconds, and I keep a rolling record of a few days’ worth. Because that’s a lot of files, I keep them in subdirectories by day and hour :

  images/
  
      2015-05-02/
  
          00/
  
              2015-05-02-0000-02
  
              2015-05-02-0000-05
  
              2015-05-02-0000-07
  
          01/
  
              (etc.)
  
      2015-05-03/

  I’m writing a script to automatically upload a timelapse of the sunrise to YouTube each day. I can get the sunrise time from the web in advance, then go back after the sunrise and get a list of the files that were taken in that period using find :

  touch -d "$SUNRISE_START" sunrise-start.txt
  
  touch -d "$SUNRISE_END" sunrise-end.txt
  
  find images/"$TODAY" -type f -anewer sunrise-start.txt ! -anewer sunrise-end.txt

  Now I want to convert those files to a video with ffmpeg. Ideally I’d like to do this without making a copy of all the files (because we’re talking 3.5 GB per hour of images), and I’d prefer not to rename them to something like image000n.jpg because other users may want to access the images. Copying the images is my fallback.

  But I’m getting stuck sending the results of find to ffmpeg. I understand that ffmpeg can expand wildcards internally, but I’m not sure that this is going to work where the files aren’t all in one directory. I also see a few people using find’s --exec option with ffmpeg to do batch conversions, but I’m not sure if this is going to work with image sequence input (as opposed to, say, converting 1000 images into 1000 single-frame videos).

  Any ideas on how I can connect the two—or, failing that, a better way to get files in a date range across several subdirectories into ffmpeg as an image sequence ?

• Ffmpeg decode H264 video from RTP stream very slow

  3 octobre 2013, par Dmitry Bakhtiyarov

  I have H264 RTP stream over network and I need to decode it. I use libx264 to encode stream and ffmpeg to decode. When I connect to server using VLC, it correct play video without any problem. But when I connect to server using my application I have a long period, when widget, which draw video from this stream, draw only one image.

  I check log file and found, that avcodec_decode_video2() set got_image into 1 very rarely ! Decoder give me new decoded frame average every 1-2 seconds, but on the server I have 12-15 fps on encoder !

  What the reasons of this delays on decoder and how I can fix its ?

  avcodec_register_all();
  
  av_init_packet(&m_packet);
  
  m_decoder = avcodec_find_decoder(CODEC_ID_H264);
  
  if (!m_decoder)
  
  {
  
      QString str = QString("Can't find H264 decoder!");
  
      emit criticalError(str);
  
  }
  
  m_decoderContext = avcodec_alloc_context3(m_decoder);
  
  
  
  m_decoderContext->flags |= CODEC_FLAG_LOW_DELAY;
  
  m_decoderContext->flags2 |= CODEC_FLAG2_CHUNKS;
  
  AVDictionary* dictionary = nullptr;
  
  if (avcodec_open2(m_decoderContext, m_decoder, &dictionary) < 0)
  
  {
  
      QString str = QString("Failed to open decoder!");
  
      emit criticalError(str);
  
  }
  
  qDebug() << "H264 Decoder successfully opened";
  
  m_picture = avcodec_alloc_frame();
  
  ...
  
      while(m_packet.size > 0)
  
      {
  
          int got_picture;
  
          int len = avcodec_decode_video2(m_decoderContext, m_picture, &got_picture, &m_packet);
  
          if (len < 0)
  
          {
  
              QString err("Decoding error");
  
              qDebug() << err;
  
              //emit criticalError(err);
  
              return false;
  
          }
  
          if (got_picture)
  
          {
  
                  //create from frame QImage and send it into GUI thread
  
              qDebug() << "H264Decoder: frame decoded!";

  I try to change some options of m_decoderContext (i.e. thread_count) but this not changing anything.

• ffserver&ffm : Fixed issues preventing ffserver write_index and files_size from being...

  20 février 2016, par Oliver Collyer

  ffserver&ffm : Fixed issues preventing ffserver write_index and files_size from being set correctly which was breaking ffserver streaming.
  I discovered that ffserver streaming was broken (it seems like it has been since 20th November) and I opened a ticket for this (https://trac.ffmpeg.org/ticket/5250 <https://trac.ffmpeg.org/ticket/5250> ;).
  I spent yesterday learning git bisect (with the kind help of cehoyos) to painstakingly track down the cause. This was made more difficult due to the presence of a segfault in ffserver during the period where the bug was introduced so I first had to identify when and how that was fixed and then retrospectively apply that fix again for each step of the second git bisect to find the actual bug.
  Anyway, the fruits of my labour are the innocent looking patch below to correct a couple of typos and define a valid range for two variables.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] ffserver.c
  • [DH] libavformat/ffmdec.c