[vdr] DVD with AC3 audio question

Kartsa kari at kniivila.com
Tue Mar 7 16:39:40 CET 2006


From: "Dr. Werner Fink" <werner at suse.de>
> On Tue, Mar 07, 2006 at 09:04:59AM +0200, Kartsa wrote:
>>
>> Now I tried without the -a option and got the PCM light on in the 
>> receiver
>> but there were no sound. Not even noise. I got VDR somehow freesed while 
>> I
>> was testing when I was trying to select the audio (for some reason there
>> seemed to be two audio tracks on the DVD even though I had put there only
>> one :/). There was something like "tried to open OSD although OSD 
>> allready
>> open" in the log file (I can not verify that right now). So I had to 
>> reboot
>> in order to get normal working state again. Then it began to record and I
>> could not test with a commercial DVD (wife factor, you know). But I have 
>> to
>> say that the DVD I made works fine in my set top DVD player.
>>
>> Anyway the reason can then be my receiver if it tests the bit and ignores
>> PCM structure but somehow stops the noise.
>
> For small AC3 frames (each with a delay of 32ms at 48kHz) which
> are filled into a PCM frames of 6144 bytes (32ms at 48kHz) with
> a special start sequence and padded with zeros you get for the
> most time silence if the PCM frames are handled as a linear PCM
> stream.
>
>> So how is it that this setting seems to work for some and not for some
>> (unles it is all about the receiver).
>
> IMHO the receiver will work if and only if the nonlinear data bitw
> is set in the S/P-DIF data transfer stream.  The problem could be
> that not only the DVB-S FF cards can not set this bit but also
> some older soundcards or soundchips can not set this bit.
>
> On the other hand, without the nonlinear data bit some receivers
> may not like gaps in the data stream caused by underruns (e.g.
> high load or high data rates which can not handled by the dvd
> plugin and/or VDR) and switch back into linear PCM mode.
>
So now I have tried with a DVD I made and a commercial DVD. Both DVD's works 
in my settop DVD player. Both lits the PCM sign in my external decoder. I 
have connected my vdr box straight to decoder from ff cards J2 connector. 
I've checked and double checked that J2 is connected the right way. When 
SPDIF is connected to decoder normal channel viewing becomes impossible 
because the picture becomes mosaic as if I would have poor antenna signal 
but it does not affect the quality of DVD picture. Detaching the cable 
restores the picture. This could ofcourse be due to the fact that both vdr 
and receiver are connected to antenna wall outlet (not the same though).

I've also checked http://www.vdr-wiki.de/wiki/index.php/DD-Receiver my 
receiver and the list says Status PCM is OK.

Now I have vdr 1.3.43 with CVS DVD plugin.
Btw, what do I have to have to get subtitles out of DVD? I have normal 
subtitle plugin installed for DVB subtitles.

Any suggestions :(

\\Kartsa 



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