[linux-dvb] Re: Mplex doesn't work

[Carsten Koch <Carsten.Koch@icem.de>]

Henning Holtschneider wrote:
....
> What happens if there are reception errors in the broadcast? From my
> understanding so far, the data is broadcasted like this:
> 
> V V V V A V V V V A V V V V ...
> 
> So, if there is any perturbance, the MPEG decoder will drop frames and
> continue to play the audio packet until it gets enough data for the full
> video+audio stream again. Is this correct?

So you are saying, the station broadcasts
   V1a V1b V1c V1d A1 V2a V2b V2c V2d A2  ....

And for some reason V2c gets lost, so now we have

   V1a V1b V1c V1d A1 V2a V2b     V2d A2  ....

?

That sounds like a reasonable explanation to me.


I would assume that in the above situation we really see

   V1a V1b V1c V1d A1 V2a V2b V2b V2d A2  ....
                              ^^^

When we are watching the program "live"?

The question is: why is V2b replicated when we watch it 
live but dropped when we record?


So I guess there are three ways to fix this:

1) The driver supplies the missing frame.
   100% WYSIWYG.

2) VDR detects missing frames during recording (using the PTS?) 
   and keeps inserting the last good frame until the recording is
   back in sync.

3) VDR detects missing frames during replay (using the PTS?) 
   and keeps inserting the last good frame until the playback is
   back in sync.



Carsten.


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