[linux-dvb] AC3 works with Pro7 and PW (was ...towards AC3sound)

[Stefan.Hagendorn@lindy.cc]

Hi all,

after applying the patch to strip the header, it is now possible to replay
ac3data from Pro7 and from Premiere World. Strangely the header strip is
not necessary at Pro7 .. here it works with and without header ... on PW
the header must be striped for ac3dec.

I'm not an expert regarding mpeg2 .. but striping the PTS should be no
problem at all because the external programm cannot sync with the video.
Maybe vdr should check the PTS before striping it to get the most possible
sync before the stream leaves VDR ?!?!

Something like:

-analyze pts
-sync via pts to video
-strip header
-send to external pipe

Greetings
Stefan

P.S. Klaus again nice work ... and a dream come true ... a VDR Box with AC3
... wwowwwww


                                                                                                                          
                    Klaus Schmidinger                                                                                     
                    <Klaus.Schmidinger@c        An:     linux-dvb@linuxtv.org                                             
                    adsoft.de>                  Kopie:                                                                    
                    Gesendet von:               Thema:  [linux-dvb] Re: Antwort: Re: AW: Antwort: AW: Re: VDR: first step 
                    kls@cadsoft.de              towards AC3sound                                                          
                                                                                                                          
                                                                                                                          
                    26.06.2001 00:01                                                                                      
                                                                                                                          
                                                                                                                          




Klaus Schmidinger wrote:
>
> Stefan.Hagendorn@lindy.cc wrote:
> >
> > Maybe we find the difference from Pro7 to Premiere World in the PES
Header
> > ....
> >
> > maybe pro7 sends the pes header in a way ac3dec recognize hem and
strips
> > them ...  Klaus can you make a testoutput with striped pes header from
> > Premiere World to send it to ac3dec ... (or maybe a small tool to strip
the
> > headers after having the stream in a file)
>
> Locate function cReplayBuffer::StripAudioPackets() in dvbapi.c and make
the
> following change to strip the PES headers:
>
>            case 0xBD: // dolby
>                 if (Except && dolbyDev) {
> ---                int written = 0;
> +++                int written = b[i + 8] + 9;
>                    int n = l;
>                    while (n > 0) {
>                          int w = fwrite(&b[i + written], 1, n, dolbyDev);
>                          if (w < 0) {
>                             LOG_ERROR;
>                             break;
>                             }
>                          n -= w;
>                          written += w;
>                          }
>                    }
>                 // continue with deleting the data - otherwise it
disturbs DVB replay
>
> I hope I've got it right, haven't tested it...

Argggghhhh....

Of course 'n' has to be reduced as well, so the complete patch is

           case 0xBD: // dolby
                if (Except && dolbyDev) {
---                int written = 0;
---                int n = l;
+++                int written = b[i + 8] + 9;
+++                int n = l - written;
                   while (n > 0) {
                         int w = fwrite(&b[i + written], 1, n, dolbyDev);
                         if (w < 0) {
                            LOG_ERROR;
                            break;
                            }
                         n -= w;
                         written += w;
                         }
                   }
                // continue with deleting the data - otherwise it disturbs
DVB replay

Sorry 'bout that - it's late already...

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
_______________________________________________________________


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