[vdr] Re: AW: Re: AC3 and Denon AVR

["Dr. Werner Fink" <werner@suse.de>]

On Thu, Feb 27, 2003 at 10:01:18AM +0100, Praml Roland wrote:
> Hmm, 
> I've the STR DB 930 QS and I didn't get it working.
> 
> BUT:
> I've burned a disc with an AC3 and a DTS track. I can play fine the
> DTS track and if I skip to the AC3 track , I can also play (sometimes)
> the AC3 track.
> If I switch the source of the receiver to an other and back again to CD
> I have...silence :-(
> It seems that the DTS frames triggers something in the receiver so that
> AC3 frames are also accepted.

There are two ways to mark the data within a S/P-DIF stream as
none audio data.

a)  2*192 The status bits of a 2*192 32bit S/P-DIF sequence for
    stereo 16 bit PCM should be used to mark the data as none audio.
    This is done with the second status bit (bit number 1) of both
    channels.

b0) The 16 bit data within the 32bit S/P-DIF words its self
    is used for transport of the none audio data.  Nevertheless
    to fullfill timings and samples rates the data should be
    included within PCM data sequence which have the same sample
    rate and takes the sme amount of time indentical of the
    uncompressed none audio data.

b1) To help the receiver to identify the PCM stream its self
    as transport stream of none audio data, four 16 bit
    words are used, the first two are `magic' words, the
    next two are used to encode informations of the
    following data 16 bit words.

b2) To ensure that the above first two are `magic' words
    are found, a longer sequence of silence should come
    first ... maybe with some null frames which encodes
    the information `attention' in the last two 16 words
    of the four 16 bit words.


... some receiver do not need a) and some do not need b2)

IMHO opinion your receiver should be used only with b2) to
switch it into decoder mode.

            Werner


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