[FFmpeg-user] what does start mean in ffmpeg output

Feurstein, Michael Michael.Feurstein at wu.ac.at
Thu May 26 12:29:34 CEST 2011


I'm in the process of doing live streaming with ffmpeg and VLC. My biggest challenge right now is getting audio and video in sync.
In my setup I am muxing a live udp stream from VLC with a live MP3 stream from Nicecast (environment: Mac OS X), restreaming it ffmpeg in order to sync it with VLC and stream it again (I know... kinda complicated but it works). I noticed the following output from ffmpeg, where start is always slightly different - I am assuming it has sth todo with the beginning of the udp stream.

Input #0, mpegts, from, 'udp://':
                Duration: N/A, start: 2597.648522, bitrate: N/A

When syncing the muxed stream with this output I need to delay audio by 8 seconds in VLC (--audio-desync=8000)

Now my question is what does the start stand for officially - milliseconds, delay...??
Google only found me this (http://web.archiveorange.com/archive/v/KKJCyjygu3YKlis65Nfq) which apparently can't be up to date otherwise this would mean 2000 seconds timestamp

Can anyone explain this to me?

Thanks a lot!

Michael Feurstein

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