[vdr] Re: [Mplayer-dvb] DTS Sound

["Uwe Weissbach" <uwe.weissbach@web.de>]

Wolfgang Fiesel wrote:

> In IEC958 format each audio sample is embedded in a 32 bit frame granularity. It
> looks like the following bit structure:
> Sync Preamle : 0-3
> Auxillary Audio Data : 4-7
> Audio sample word : 8-27
> (V)alidity bit: 28
> (U)ser data: 29
> (C)hannel status: 30
> (P)arity bit: 31
> ... 
> Ok, in case of raw PCM transmission it has to be zero to signalise the D/A converter
> true audio data. In case of error's like changing of sampling rate the V-Flag is "1"
> for some frame to force muting the D/A converter.
> In our situation (IEC61937) it is recommend to set the validity bit to logical "1"
> because we deliver not really more raw PCM data!!!
> Unfortunatly as Uwe find out this bit is always "0". I can imagine that some

Hi Wolfgang,

No - misunderstanding! I did'nt found the validity bit (28) is wrong 
but the bit 1 (second) in the channel status word, witch is
build from all the bits No. 30 is not set correct

refer to my mails 
http://www.linuxtv.org/mailinglists/vdr/2002/03-2002/msg01444.html 
and
http://www.linuxtv.org/mailinglists/vdr/2002/03-2002/msg01947.html 
for  the complete measurements (DVB and "true" AC3 signal)

Even if the AC3 autodection say AC3 signal detected, some receivers
(I got Sony and heard from Yamaha in the list) expect the data stream
labled as "non audio" or also "digital data" by *setting* this bit in the
channel status word. (This should be true for DTS, MPG, AAC also...)

>  I think we should solve this problem to be really compatible 
> with all DD receiver.
> I'll start investigation next week.

agree with you and thanks for gimme hope,
I'm not really a programmer, but if I can help you
anyway by testing and/or measuring, feel free to mail me
(away for Holiday from Thursday to Monday) 

greetings,
Uwe Weissbach

--

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