Recherche avancée

Sur d’autres sites (15007)

• How to reduce audio delay in FFmpeg using HTTP FLV stream ?

  20 février 2018, par albert200000

  I have problem with live http flv stream. I’m using the following command and it works great except for the audio. Audio has delay that increasing over time. I can fix the this by removing refresh rate option on the output (-r 30) but then stream latency goes higher for about half second.

  ffmpeg -f v4l2 -threads 0 -video_size 672X420 -i /dev/video1 -f alsa -thread_queue_size 512 -i hw:1,0 -c:a aac -ar 44100 -b:a 128k -c:v libx264 -s 672x420 -r 30 -g 60 -preset superfast -tune zerolatency -strict -2 -f flv rtmp://localhost/live/primary

  Can someone explain why this happening and what possible fixes are ?
  On the client I’m using Chrome with flv.js library.
  On the server Node-Media-Server.

• Convert M3U8 playlist to MP4 using GStreamer

  9 février 2023, par Idan

  I'm trying to convert an HLS playlist to MP4 file. The .ts files in the list are guaranteed to be h264/aac and with the same resolution (for cases when there is a EXT-X-DISCONTINUITY tag).

  



  this is the closes I got to a working pipeline :

  



  gst-launch-1.0 mp4mux name=mux ! filesink location=x.mp4 souphttpsrc location="https://remote/path/to/index.m3u8" ! decodebin name=decode ! videoconvert ! queue ! x264enc ! mux. decode. ! audioconvert ! avenc_aac ! mux.


  



  Don't really know if the result is valid as this command line gets GStreamer to play the HLS in playing time instead of fast forward and ingest as fast as possible (the list is closed with #EXT-X-ENDLIST).

  



  Second issue is that it looks to me like this pipeline is encoding the stream instead of just coping it. I don't need it to encode, only change the container. H264/aac in the .TS files is what I also need in the .MP4 file.

  



  So, is it possible to only copy and not transcode using as-fast-as-u-can ingestion and not real-life speed ?

  



  Basically, I am trying to find the GStreamer equivalent to this FFmpeg command :

  



  FFmpeg -i "https://remote/path/to/index.m3u8" -c copy x.mp4


  



  (I have to use GStreamer and not FFmpeg.)

  


• How to extract video clip from larger video based on specific time and duration

  26 juillet 2022, par user19019404

  I have video clips that get created. Each video is recorded for 5 minutes and starts at a time e.g. 10:01:20 to 10:06:19 then the next video from 10:06:20 etc. These videos are recorded at a specific frame rate, be it 5 frames or 30 frames (its dependent on the platform making the recording). The net result is NOT a 5 minute video clip but might be a 2 minute video clip (where everyone moves very quickly in the view as a result of the frame rates). I cannot restrict a 1 to 1 recording as these are generated by external systems.

  


  I need to extract specific portions out of the video. For example I need to extract from 10:03:10 to 10:03:35 (25 seconds). This would equate to 10 seconds into the video up to 14 seconds into the video, in those 4 seconds of video, 25 real world seconds are displayed.

  


  My question is do you have any guidance as to how I can calculate that each second of recording actually means 10 or 12 seconds in real life, therefore go to this frame and record to this frame for example.

  


  I have been looking at cv2.CAP_PROP_FPS to get the video frame rates, CAP_PROP_POS_MSEC and CAP_PROP_FRAME_COUNT and believe the answer might lie there, but not sure.

  


  The thinking being if I work out the frame rate of the video, the total frames then I can divide the one by the other to get to how many frames make up real world seconds (this is where I fail). This way I can run from frame to frame as a result.

  


  Thank you