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• what is The fastest way to scale down a H264 video in 2:1 ?

  12 décembre 2015, par 李天宇

  when I use ffmpeg to scale a H264 video. It seems that the video is decoded to the raw graph then scaled then encoded again. But if the speed is very critical,is there a faster way if I specify a “good" ratio like 2:1, as if I want to pick up one pixel in every four ?

  I know a bit how h264 works, 8*8/4*4 pixels are coded as a group,so it’s not easy to pick up 1/4 pixels in its range. But is there a way to merge 4 group into one quickly ?

• exclude specific streams (e.g. teletext) from ffmpeg conversion

  17 août 2019, par leone1522

  I want to convert several video files (captured from television) to another format, but I want to remove some specific streams. For example, this is one of my input files :

  $ ffprobe -hide_banner -i 'Easy Rider.ts' 2>&1|grep Stream
  
      Stream #0:0[0x4f6]: Unknown: none ([5][0][0][0] / 0x0005)
  
      Stream #0:1[0x4fc]: Unknown: none ([12][0][0][0] / 0x000C)
  
      Stream #0:2[0x13f7]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn, 100 tbc
  
      Stream #0:3[0x13f8](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s
  
      Stream #0:4[0x13f9](fra): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s
  
      Stream #0:5[0x13fa](deu): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
  
      Stream #0:6[0x13fb](deu): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  
      Stream #0:7[0x13fc](mul): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s
  
      Stream #0:8[0x13fd](mis): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s (visual impaired) (descriptions)
  
      Stream #0:9[0x13fe](fra): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
  
      Stream #0:10[0x13ff](deu): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)

  From this file, I want to keep

  • Stream #2 (h264 video)
  • Stream #3 (mp2 audio in german)
  • Stream #10 (dvb_subtitle in german)

  In other words, I want to exclude from conversion

  • all streams of unknown type
  • all audio streams other than german
  • all streams for visual impaired or hearing impaired
  • all dvb_teletext streams

  Of cause, I can do some awk scripting to construct a command like

  $ ffmpeg -hide_banner -ignore_unknown -i 'Easy Rider.ts' -map 0:2 -map 0:3 -map 0:10 -vcodec copy -acodec copy -scodec copy xx.ts

  But I am searching for a solution using ffmpeg’s mapping facilities.
  I already found Mapping streams by language in FFmpeg, which led me to

  $ ffmpeg -hide_banner -ignore_unknown -i 'Easy Rider.ts' -map 0:v -map 0:m:language:deu -vcodec copy -acodec copy -scodec copy xx.ts

  This command creates a file, which still has subtitles for hearing impaired and the dvb_teletext in it

  $ ffprobe -hide_banner -i xx.ts 2>&1|grep Stream
  
      Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn, 100 tbc
  
      Stream #0:1[0x101](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s
  
      Stream #0:2[0x102](deu): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006), 492x250
  
      Stream #0:3[0x103](deu): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  
      Stream #0:4[0x104](deu): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)

  Up to now, I did not find a way to exclude those streams from the output. Any idea ?

• FFmpeg live streaming for media source extensions(MSE)

  1er septembre 2022, par IceCreamVan

  I try implement video live streaming from RTSP stream to webpage with media source extensions(MSE) with using FFmpeg

  


  Expected system diagram.

  


  

  


  I know that this task can realize with HLS or WebRTC, but HLS have large delay and WebRTC very hard to implementation.

  


  I want catch RTSP stream with FFMPEG split it to ISO BMMF(ISO/IEC 14496-12) chuncks in "live mode" and send it to my web server by TCP in which i restream this chunks to webpage by websocket. In webpage i append chunck to buffer sourceBuffer.appendBuffer(new Uint8Array(chunck)) and video play in streaming mode.

  


  Problem in first step with ffmpeg i can easy split RTSP stream to segments with this

  


  ffmpeg -i test.mp4 -map 0 -c copy -f segment -segment_time 2 -reset_timestamps 1 output_%03d.mp4


  


  but i cant redirect output to tcp ://127.0.0.1 or pipe:1, if i correctly understood segment not work with pipes. For example i can easy send video frames in jpg by TCP with image2 catch ff d9 bytes in TCP stream and split stream to jpg images.

  


  ffmpeg -i rtsp://127.0.0.1:8554 -f image2pipe tcp://127.0.0.1:7400


  


  How i can split RTSP stream to ISO BMMF chunks for sending to webpage for playing with media source extensions ? Or other way to prepare RTSP stream with FFmpeg for playing in MSE. Maybe i not correctly understood how working MSE and how prepare video for playing.