[vlc-devel] Re: Multicast udp streaming from playlist - problems

Benjamin PRACHT bigben+spam at videolan.org
Wed Sep 1 17:01:15 CEST 2004

On Wed, Sep 01, 2004, Dermot McGahon wrote :
> * libdvbpsi error (PSI decoder): TS discontinuity (received 10, expected 0)

Basically, that means that one or several TS packet have been lost
(probably by the network). this is no critical error

> * [00000229] main audio output warning: buffer is 204733 in advance,  
> triggering downsampling
>   What is the 204733 measured in? Microseconds?
>   What does the downsampling achieve? A/V sync?

yes, this is measured in microsecond. Unlike other video players (wh
syncronize all streams on audio), VLC syncronize all es on timestamps
(dts) given in the stream. This, among other things, allows a better
management of buffers. The drawback is that you sometimes need to
resyncronize audio streams, which are outputed at the samplerate defined by
the soundcard). To achieve this, you need to play the audio stream at
higher (upsampling) or lower (downsampling) samplerate for a few 1/10s or seconds.

>    The stream seems altogether wrong at this point, to state the
>    obvious.

Well, you seem to have some packet loss, related to network issues or a
lack of ressources on the server/client.
>    What are the output and input PTS?

PTS is for processing timestamp. It is the timestamp at which the
decoder should treat the data.
>    What could cause it to be killed?

Well, good question. There is no fatal error shwn in your logs, only
messages showing packet loss from or processing errors from time to
time. If this log is the result of several minutes / hours of streaming,
this shouldn't be too a big deal...


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