[vdr] Re: DVD-AC3-Playback

["Andreas Schultz" <Andreas.Schultz@parc-technologies.com>]

Hi all,

> -----Original Message-----
> From: vdr-bounce@linuxtv.org 
> [mailto:vdr-bounce@linuxtv.org]On Behalf Of
> Klaus Schmidinger
> Sent: Saturday, November 24, 2001 4:54 PM
> To: vdr@linuxtv.org
> Subject: [vdr] Re: DVD-AC3-Playback
> 
> 
> 
> Andreas Schultz wrote:
> > 
> > Hi all,
> > 
> > There have been to much complaints about DVD AC3 playback. So i had
> > quick look at it.
> > There appears indeed to be a problem with the way how DVD 
> AC3 frames are
> > sent to external decoders.
> > 
> > Everyone with problems, could you please try to modify line 772
> > (cPlayBuffer::PlayExternalDolby()) in dvbapi.c.
> > 
> > orignal:
> > 
> > int written = b[8] + 9; // skips the PES header
> > 
> > should be changed to:
> > 
> > int written = b[8] + 13; // skips the PES header
> > 
> > This will most likely break AC3-out for DVB streams.
> > 
> > Please report your findings ASAP especialy wether this change indeed
> > breaks DVB AC3 or not.
> 
> I don't have any detailed information on this AC3 (header) format,
> but from what I have observed there might be a chance to dynamically
> detect whether these four bytes should be skipped or not.
> 
> Please try this instead of the above change
> 
>            int written = b[8] + 9; // skips the PES header
>            if (b[written] == 0x80)
>               written += 4;

mhh, kleine Korrektur, das sollte IMHO heissen:

if ((b[written] & 0xf0) == 0x80)

> and test if this can play AC3 sound from DVDs as well as DVB
> recordings made with VDR.
> 
> Note that this is just a wild guess - if anybody can come up with
> information on how one can correctly detect whether these 
> four header bytes
> are present or not, please let me know.

Gruss

   Andreas
> 
> Klaus
> -- 
> _______________________________________________________________
> 
> Klaus Schmidinger                       Phone: +49-8635-6989-10
> CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
> Hofmark 2                               Email:   kls@cadsoft.de
> D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
> _______________________________________________________________
> 
> 
>