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• C++ How to make a H.264 encoded buffer in RAM from rtsp stream and write it to file if needed without decoding

  19 septembre 2023, par FenyaHere

  The task is to receive data from H.264 encoded rtsp stream and keep last 60 seconds of it in RAM to save to file *.mp4 when needed without decoding. Right now i'm using OpenCV to decode frames, store an array of decoded cv::Mat and when event triggers i just copy the buffer, encode it and save to file. But current method uses too much memory and CPU to decode/encode and keep unencoded frames.

  


  I've tried to look into gstreamer library but failed to come up with a solution (i'm new to gstreamer). Is there an easy way to do it, that i'm missing ? Thank you for your help !

  


• How to simplify the script for ffmpeg ?

  27 mars 2018, par Pravesh Kumar

  I want this script to be simplified

  I am having this given simple script ; I would like to simplify this script can anyone help me to add text with the proper time interval and fade in and out effect.

  ffmpeg -y -i video.mp4 -filter_complex \
  
  "[0]split[base][text];[text] \
  
  drawtext=fontfile=gvr.otf:text='Which of these is not an event listener adapter defined in the java.awt.event package?': fontcolor=white: fontsize=40: x=100:y=200, \
  
  format=yuva444p,fade=t=in:st=1:d=1:alpha=1,fade=t=out:st=8:d=1:alpha=1[subtitles]; \
  
  [base][subtitles]overlay" test_out.mp4
  
  
  
  ffmpeg -y -i test_out.mp4 -filter_complex \
  
  "[0]split[base][text];[text] \
  
  drawtext=fontfile=gvr.otf:text='a) public void apple(String s, int i) {}': fontcolor=white: fontsize=40: x=100:y=(200) + 50 * 2, \
  
  format=yuva444p,fade=t=in:st=3:d=1:alpha=1,fade=t=out:st=8:d=1:alpha=1[subtitles]; \
  
  [base][subtitles]overlay" test_out1.mp4
  
  
  
  ffmpeg -y -i test_out1.mp4 -filter_complex \
  
  "[0]split[base][text];[text] \
  
  drawtext=fontfile=gvr.otf:text='b) public int apple(int i, String s) {}': fontcolor=white: fontsize=40: x=100:y=(200) + 50 * 3, \
  
  format=yuva444p,fade=t=in:st=4:d=1:alpha=1,fade=t=out:st=8:d=1:alpha=1[subtitles]; \
  
  [base][subtitles]overlay" test_out2.mp4
  
  
  
  ffmpeg -y -i test_out2.mp4 -filter_complex \
  
  "[0]split[base][text];[text] \
  
  drawtext=fontfile=gvr.otf:text='c) public void apple(int i, String mystring) {}': fontcolor=white: fontsize=40: x=100:y=(200) + 50 * 4, \
  
  format=yuva444p,fade=t=in:st=5:d=1:alpha=1,fade=t=out:st=8:d=1:alpha=1[subtitles]; \
  
  [base][subtitles]overlay" test_out3.mp4
  
  
  
  ffmpeg -y -i test_out3.mp4 -filter_complex \
  
  "[0]split[base][text];[text] \
  
  drawtext=fontfile=gvr.otf:text='d) public void Apple(int i, String s) {}': fontcolor=white: fontsize=40: x=100:y=(200) + 50 * 5, \
  
  format=yuva444p,fade=t=in:st=6:d=1:alpha=1,fade=t=out:st=8:d=1:alpha=1[subtitles]; \
  
  [base][subtitles]overlay" test_out4.mp4

• QtAV/ffmpeg youtube : bufferProgressChanged and positionChanged together

  11 décembre 2017, par Maignan Arnaud

  I’m trying to make a streaming tester with QtAV, under linux, mac and windows.
  Under these 3 systems, when I play a youtube video
  like :

  https://r3---sn-gx1v2vax-atne.googlevideo.com/videoplayback?initcwndbps=3892500&dur=12.208&signature=...

  The problem is :
  The player continues to change it’s position (timer) while it’s still buffering.
  I noticed this only with youTube videos (other video providers are working well) but it’s the one I need to implement.

  Reproduction steps :
  Compile ffmpeg with SSL, take Youtube URL (1080p) from raw page, bandwidth clamping to stalled your video, read this url with QtAV and output this player events :
  mediaStatusChanged, loaded, stateChanged, started, notifyIntervalChanged,
  bufferProgressChanged, positionChanged

  First bad solutions :
  Changing player config like setBufferValue, dont seems to solve my problem (but I may not have tried all possible combinations)

  m_player->setBufferMode(BufferMode::BufferTime);//BufferTime, BufferBytes, BufferPackets
  
  //m_player->setSeekType(SeekType::KeyFrameSeek);//AccurateSeek, KeyFrameSeek, AnyFrameSeek
  
  m_player->setBufferValue(1000);

  Searching to modify QtAV code source, seems complicated to me, but I noticed that void AVPlayer::timerEvent(QTimerEvent *te) have a lot of commented code and particularly, this comment below makes me think that maybe QtAV developper didn’t implement everything yet :

  qint64 AVPlayer::position() const
  
  {
  
      // TODO: videoTime()?
  
      const qint64 pts = d->clock->value()*1000.0;
  
      […]
  
  }

  Expected behavior :

  When bufferProgressChanged, the video must be paused, and replay only when buffer is 100%.
  For example, when mediaStatusChanged=BufferedMedia.
  So the event positionChanged should never change, unless the event bufferProgressChanged == 1 or 0

  Actual behavior :
  See complet logs file :
  https://github.com/wang-bin/QtAV/issues/1004