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• How can I intercept encoded video data using ffmpeg with C ?

  24 février 2017, par TerNer

  First of all, I hope you’ll understand my poor english skill. I’ll do my best to write question about it.

  I’m currently developing some application. That application will captures desktop and encodes to MP4 video and send mp4 video data/chunks to another clients (all this process should run in memory not file). so another client should can play mp4 video/data/chunks that received from server.

  so I used avio = avio_open(...) and reassigned write function as like avio->write_packet = some_function. but this way seems not "generate" mp4 file/chunk correctly. and It seems the original write_packet callback having actual logic that write packet to a file. but I don’t want to write to a file. so I was thinking about it for a week but I did’t getting any of idea about it.

  so my question is : How can I intercept "encoded" video data that should processed by avio->write_packet ?

• How to sync multiple rtsp inputs in ffmpeg ?

  9 décembre 2019, par KOMsandFriends

  I am combining multiple rtsp streams from local network cameras to a single output using ffmpeg. In the resulting video, the videos are out of sync.

  ffmpeg -loglevel warning \
  
          -f image2 -loop 1 \
  
          -i logo.png \
  
          -rtsp_transport tcp -thread_queue_size 1024 \
  
          -i "rtsp://10.0.0.1" \
  
          -rtsp_transport tcp -thread_queue_size 1024 \
  
          -i "rtsp://10.0.0.2" \
  
          -rtsp_transport tcp -thread_queue_size 1024 \
  
          -i "rtsp://10.0.0.3" \
  
          -filter_complex "[3:v][2:v][0:v][1:v]xstack=inputs=4:layout=0_0|w0_0|0_h0|w0_h0[v]" \
  
          -map "[v]" \
  
          -filter_complex "[1:a][1:a]amerge=inputs=2[aout]" -map "[aout]" \
  
          -vcodec libx264 -pix_fmt yuv420p -r 30 -g 60 \
  
          -preset fast -b:v 2400k -maxrate 4600k -bufsize 6000k \
  
          -acodec aac -ar 44100 -b:a 128k \
  
          -f flv "rtmp://live-api-s.facebook.com:80/rtmp/$STREAMKEY"

  If we take the first input (0) (10.0.0.1) as reference, the second input (1) is initially about 1000ms ahead, the third input (2) is about 2000ms ahead. It looks like the offset is even slightly increasing over time.

  I tried to exchange the different inputs (e.g. 10.0.0.3 to input 0, 10.0.0.1 to input 2), then 10.0.0.1 is ahead of 10.0.0.3. So I would assume this is a matter of ffmpeg and how it processes the inputs.

  How could I sync the different sources in the output ?

• FFmpeg live streaming with a camera source but the camera source can be changed in realtime

  11 janvier 2018, par Faiz A. Farooqui

  I have a scenario where I would be using a camera source for the live streaming onto YouTube / Facebook.

  But I have more than one camera source, so basically I need to change the camera source in real time.

  Streaming with a single camera source is working fine for me, here below is the command I am using for the same.

  ffmpeg 
      -f avfoundation -framerate 30 -i "1:0"  # Camera Source with Mic
      -f avfoundation -framerate 30 -i "0"    # Screen Capture
      -loop 1 -i background.jpg               # Background Image
      -filter_complex "
          [2:v] format=argb,colorchannelmixer=aa=0.5 [base] ;
          [0:v] setpts=PTS-STARTPTS, scale=1440x900 [upperleft] ;
          [1:v] setpts=PTS-STARTPTS, scale=576x324 [lowerright] ;
          [base][upperleft] overlay=shortest=1:x=20:y=20 [interim] ;
          [interim][lowerright] overlay=shortest=1:x=1320:y=740
      " 
      -preset fast 
      -pix_fmt bgr0 
      -s 1920x1080 
      -threads 1 
      -f flv "rtmp ://a.rtmp.youtube.com/live2/stream-api-key"
  

  Here I am using a camera source and a screen capture source with a background image for live streaming, and I need to change the camera source in real-time.