Re: Outputting multichannel sound through the optical link??
Re: Outputting multichannel sound through the optical link??
- Subject: Re: Outputting multichannel sound through the optical link??
- From: William Stewart <email@hidden>
- Date: Wed, 10 Feb 2010 11:45:50 -0800
On Feb 9, 2010, at 9:38 PM, Ryan Walklin wrote:
On 10/02/2010, at 3:05 PM, William Stewart wrote:
I think I've been clear in my statements about what we have
supported in released products.
I see little future for SPDIF - you can't even use it to reliably
transfer 24bit audio at 48kHz - and there is no discovery mode that
can tell you whether what you are doing is even supported or
possible... It is quite possible to output Dolby Digital or DTS
over spdif and listen to very nasty noise.... To make a better user
experience you really need to know what the capabilities of the
devices are - so the EDID mechanism of HDMI/DP is a fine solution
to this. ADAT is even worse than SPDIF from a compatibility point
of view (less devices support it), so I see no future in this.
On the contrary, I think SPDIF has a long future ahead, at least in
consumer 5.1 audio.
The blu-ray spec explicitly listed SPDIF as "backwards compatible"
mode. It didn't describe SPDIF as a future looking format to support,
so that's an interesting point of reference as well I think
HDMI certainly is becoming ubiquitous, but I don't think any of the
new lossless HD audio formats offer a significant gain on DTS/DD
audio to encourage adoption in consumer hardware. They certainly
don't offer a compelling reason to daisy-chain adaptors as has been
suggested. Nearly all existing receivers support DD/DTS over SPDIF,
all shipping Macs do, and there is an extensive ecosystem around it.
Certainly I've found 5.1 AC3 at 448kbps and above to be transparent,
and 5.1 AAC to be transparent at 384kbps. I suspect a lot of the
"difference" between these compressed formats and lossless encoding
is in the mixing and dynamic range.
I think you have a narrow view of the possible use cases for surround
audio.
This is the model we have for DVD playback today (and apple's movies)
and it is fine for that as long as it is just movie playback you want.
The restrictions this places on the user experience is probably ok
(you can live with it). But you can't mix in director commentaries,
etc, UI sounds, sounds from other apps, while this movie is playing.
This is a long standing issue, and you can see the affects of this in
the UI for using this in DVD Player (or iTunes with AC-3 playback). If
you haven't tried this, then I think you should so you understand how
this affects the user experience for a system such as a mac (or
AppleTV).
If you want to do anything interactive, real-time or low latency
(games!), then this becomes a substantial problem for a number of
reasons.
Bill
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