Fw: Audio Digital Data Streams

["Gareth Cook/UK/IBM" <gcook@xxxxxxx>]

As a side bit of info - AC3 streams on
LaserDiscs are RF encoded onto the right analogue track (needing a £100
bloody converter) whereas DTS on a LaserDisc takes up the digital audio
tracks (no standard stereo audio then) - the optical out to the
decoder/receiver is all that is needed.

G.

Gareth Cook Senior Engineering Specialist EMEA ED, IBM SWG Lotus Park, Staines, TW18 3AG

Office:  +44 (0) 1784 445 166 Mobile:  +44 (0) 7980 445 166 Fax:      +44 (0) 1784 499 166

Work: g@xxxxxxx Personal: g@xxxxxxx AIM Chat : TheBoyG MSN Chat : chat@xxxxxxx

----- Forwarded by Gareth
Cook/UK/IBM on 27/03/2002 10:09 -----

Discussion
Main Topic

"Mark Harrison" <Mark.Harrison@xxxxxxx>
Today 09:36

.

Subject: .	RE: [ukha_d] Audio Digital Data Streams .
Category:

Kenneth,

That was what I meant by "natively digital". DD/DTS are digital streams,
mixed digitally, and intended to be processed entirely within the
digital domain. The cludge of modulating the stream onto RF was an
implementation hack to get it retro-fitted onto a format never intended
to carry it. Not quite as neat as the hack required to fit it onto 35mm
film, which is to have a separate mag strip down the _edge_ of the film,
in the gaps between the sprocket holes ;-)

By comparison, Dolby Pro-logic, and the earlier formats, are analogue
streams. Yes, they may be digitised, but except in very specialised kit
like the Meridians, the processing required to extract the extra
channels is done in the analogue domain.

In practice, the "EC standard" has lost in the market place. It's very
hard to find a Region 2 DVD player that _doesn't_ support Dolby Digital,
and most Region 2 software is supplied with a DD soundtrack.

Most, to be fair, also has a stereo PCM soundtrack, and when I first got
a DVD player, that's what I listened to. The Surround Sound processing
was a later (second-hand) purchase. I knew I wanted the Meridians, and
decided to save for them rather than spending on a cheaper system "for
the moment" :-)

Regards,

Mark Harrison
Head of Systems, eKingfisher
-----Original Message-----
From: Kenneth Watt [mailto:kennwatt@xxxxxxx]
Sent: 26 March 2002 23:25
To: ukha_d@xxxxxxx Subject: RE: [ukha_d] Audio Digital Data Streams


AFAIK, you are correct Mark.

What I can tell you is that for AC3 from LD you *need* the RF decoder in
the amp to enable the 5.1 matrix.

On DD/DTS 5.1, 6.1 or 7.1 from DVD primarily but also virtually any
other source then either a digital optical or co-axial is needed, it
cannot be decoded through normal analogue connections to my knowledge.
Don't ask me why, I just know that that's it!

As for ITVD, again AFAIK, the digital out allows you to decode the audio
signal off board, it has no function other than that and I have played
about with the digital out from my Nokia. This leads me to the
conclusion that Nokia perhaps saw the possibility of broadcasting being
done in DD or MPEG ?veloped (mainly) by tem from Philipsd encoding of
choice problem with this. ff board, it has no functio , it cannot be
decoded(??) and added it just in case however, the broadcasters have a
problem with this.

IIRC, the EC decided that the digital sound encoding of choice was to be
the MPEG system developed (mainly) by Philips but the consumers choice
was DD, so the broadcasters have a tough choice ahead. Go with DD which
most people have equipment for because of the DVD boom, or go with the
EEC standard and piss everyone off! ;-)

So to answer the actual question, no the Nokia box does not output DD or
any other digital surround as it does not receive the signal to enable
it to do so. You *will* get Dolby Surround, but it will only be
marginally better by using an offboard DAC as the signal is pants anyway
to start with from ITVD in 99% of cases.

As Mark rightly points out though, Phil is the real expert on this
stuff.

HTH

K.

> -----Original Message-----
> From: Mark Harrison [mailto:Mark.Harrison@xxxxxxx]
> Sent: 26 March 2002 17:49
> To: ukha_d@xxxxxxx > Subject: RE: [ukha_d] Audio Digital Data Streams
>
> The following multi-channel formats are carried natively digital, and
> include tagging to specify which format they're in. In addition, they
> carry further tags to specify how many discrete audio channels are
> included. Dolby Digital, for example, has several different varieties,
> between mono and 6 channels (5 full-frequency, plus 1 limited
bandwidth
> intended for Bass.)
>
> - Dolby Digital (between 1 and 6 discrete channels)
> - DTS (between 1 and 6 discrete channels)
> - MLP (between 2 and 6 discrete channels, I think??????????)
>
> The following multi-channel formats are carried natively analogue, on
> two channels, and don't include any tagging. They just rely on phase
> processing to try to "decode" a rear channel.
>
> - Stereo
> - Dolby Surround (three channels modulated into two)
> - Dolby Pro-logic (four channels modulated into two)
>
>
> The real expert on all of this is Phil Harris.
>
> Mark Harrison
> Head of Systems, eKingfisher
>
> -----Original Message-----
> From: Kevin Hawkins [mailto:lists@xxxxxxx]
> Sent: 26 March 2002 16:24
> To: UKHA Group
> Subject: [ukha_d] Audio Digital Data Streams
>
>
>     Is all the info necessary to define the exact format of the data
> encoding always transmitted in an audio digital data stream or is it
> sometimes ambiguous ?
>     Specifically with ITV Digital (assuming it is still around by the
> time you read this), do they ever transmit anything apart from
standard
> stereo or Dolby Surround ? (I heard not as they don't have the
> bandwidth). When they do transmit Dolby Surround is there anything in
> the data stream so that you know it is in surround rather than
ordinary
> stereo ? I do have a digital output from my Nokia ex OD box.
>
>     Kevin
>
>
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