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• ffmpeg video stream delay in playback ?

  22 février 2017, par user685869

  I’m trying to capture and stream video from a 5MP USB camera using ffmpeg 3.2.2 on Windows. Here’s the command line that I’m using :

  ffmpeg -f dshow -video_size 320x240 -framerate 30 -i video="HD USB Camera" -vcodec libx264 -preset ultrafast -tune zerolatency -g 60 -f mpegts udp://192.168.1.100:10000

  The destination for my stream (an Ubuntu box on the same subnet) is running ffplay via :

  ffplay -i udp://127.0.0.1:10000

  This works but the video stream seems like it’s delayed by 8 - 10 seconds. It’s my understanding that the destination can’t begin displaying the stream until it receives an I-frame so I tried specifying a GOP value of 60 thinking that this would cause an I-frame to be inserted every 2 seconds (@ 30 FPS).

  The Windows machine that’s doing the transcoding is running an i7-3840QM @ 2.80GHz and has 32 GB RAM. FFmpeg appears to be using very little CPU (like 2%) so it doesn’t seem like it’s CPU bound. Just as a test, I tried ingesting an MP4 file and not doing any transcoding (ffmpeg -re -i localFile.mp4 -c copy -f mpegts udp://192.168.1.100:10000) but it still takes several seconds before the stream is displayed on the Ubuntu system.

  On a related note, I’m also evaluating a trial version of the Wowza Streaming Engine server and when I direct my ffmpeg stream to Wowza, I get the same 8 - 10 second delay before the Wowza test player starts playing it back. For what it’s worth, once the stream starts playing, it seems to be running fine (other than the fact that everything is "behind" by several seconds).

  I’m new to video streaming so I might be missing something obvious here but can anyone tell me what might be causing this delay or suggest how I might further troubleshoot the problem ? Thank you !

• Using ffmpeg to get a passthrough stream and create an audio resource for discordjs/voice ?

  5 novembre 2022, par Zer0

  I have access to an hls manifest file which i can use to download a song.
I use the following command to download it/pipe it to stdout :
ffmpeg -i 'https://api.someurl.com/1/2/3/stream.ismd/manifest.m3u8' -vn -sn -f flv -c copy -|ffmpeg -i - -b:a 192k -f mp3 -.

  


  I am successfully able to output a playable mp3 from this command.

  


  I am looking for a way to get the same kind of result in nodejs and get a readable stream from the final download and then pipe it to createAudioResource() to make it playable in a discord voice channel.

  


  There is a nodejs module called m3u8stream which i tried using with the code mentioned below but i couldnt get it to work as my knowledge of nodejs streams is limited and the documentation is confusing to understand.

  


  const stream = new PassThrough()
let resource
const stream = m3u8stream('https://api.someurl.com/1/2/3/stream.ismd/manifest.m3u8', {parser : 'm3u8',
requestOptions : {headers : {"content-type" : "video/mp4"}}
}).pipe(stream)
stream.on('data', d=>{resource = createAudioResource(d)})
player.play(resource)


  


  This code did not work and i am assuming this has something to do with m3u8stream itself because piping the stream to fs.createWriteStream('file.mp4') as shown in their example results in a zero kb mp4 file.

  


  I am sure there is be a better tool or a way to get a stream from the manifest and get it to play on discord and i would be happy to know about them as i am not bound to use ffmpeg for this.
Any help to make this work is appreciated. Thanks !

  


• mp3/aac trim precision issue

  27 janvier 2020, par Massimo Vantaggio

  Due to mp3/aac codec doesn’t support that level of trim precision so im unable to get rounded container duration (without this 6 ms) :

  ffprobe -v error -show_entries format=duration \
  
  >   -of default=noprint_wrappers=1:nokey=1 output_audio.mp4
  
  372.006000

  MP4box generation get 6 ms more for every cycle :

  [...]
  
  Next generation scheduled in 3895 ms (DASH time 412006 ms)
  
  [...]
  
  Next generation scheduled in 3895 ms (DASH time 414012 ms)

  My MP4box command :

  MP4Box -dash-live 2000 -subdur 4000 -bound -segment-timeline -no-cache -profile dashavc264:live -subsegs-per-sidx -1 -mpd-refresh 4 -time-shift 16 -min-buffer 2000 -url-template -insert-utc -bs-switching no -run-for 86400000 -dash-ctx ../../live/log.txt -out ../../live/manifest.mpd ../current/output_1080.mp4:bandwidth=4800000#video ../current/output_720.mp4:bandwidth=2400000#video ../current/output_360.mp4:bandwidth=800000#video ../current/output_audio.mp4:bandwidth=384000#audio

  after 50% of the advertised duration an error will occur (probably)

  I say probably because the time for testing it is very long so may ask if the mp4box command provide for a stable loop or if the error will occur, and if yes, it will occur, may ask an help to debug my command line on mp4box to avoid this issue ?

  Im sorry but trial and error it’s too long since every try is about 24 hours..

  Dash.js web based purpose.

  Thansk in advance !