[Ffmpeg-devel] Bug in ASF mux? (was: RE: [Ffmpeg-user] reduce the time delay)

[Dario Andrade]

> > Widows Media Player is delayed 3 seconds. How can I further reduce the
> time
> > delay. The movie is distribued within LAN, so I do not care the bitrate.
> > Please help me. Thank you!
> 
> The Windows Media client adds a delay to allow for buffering. The delay is
> configurable within the client settings, but there will always be some
> delay due to encoding, propagation and stream setup delay. Different
> clients watching the same "Live" stream will often exhibit different
> delays.
> 
> Ian Grush
> 

I have noticed that the ASF multiplexer in ffmpeg is not really optmized
according to specs. There is something related to preroll header field, and
timestamps.
A normal ASF file (there a really nice utility called Windows Media ASF
Viewer, http://www.microsoft.com/windows/windowsmedia/format/ASFViewer.aspx,
that may be used to examine the ASF file further) has a preroll equal to the
buffer window (normally 3 or 5 secs), and timestamps (actually packet send
times) beginning exactly at the specified preroll (from the header field).

>From the files generated by ffmpeg, I could see there are some glitches
(such as local playback delay in the windows media player, not the one
created by the network buffering, etc...). Is anyone willing to fix it?

Regards, hope it helps,
Dario Andrade