[opendtv] Re: PR: Enhanced AC-3 Audio Specifications Serve Multiple Applications
- From: "John Willkie" <jmwillkie@xxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 8 Apr 2004 09:54:42 -0700
First of all, I tend to agree with John Shutt and Mark Schubin in virtually
all details.
Having had some experience with Dolby licensing and having talked with MANY
people who've had extensive experience with Dolby licensing, I wonder how
widely your "understanding" is shared by the people on the other side of the
table from Dolby? I guess I'll have to ask at NAB some of those involved
about this.
The "if it ain't mandatory, we're going to charge for the second decoder"
poise certainly sounds fishy. What changed by not making dual decoders
mandatory? They lost the potential to sell 1,600 additional encoders?
This affects me personally. I have developed a canonical AC-3 encoder
Active X user control for my metadata generator, and will in short order
extend that to directly interface with Ac-3 encoders. I'm rather proud of
the thing, even at this point. However, it has to be hobbled in use: since
there are no dual stream decoders, there is no realistic possibility to
enable stations to use the Music + Effects, Dialogue, Voiceover and
Commentary modes. So, half of the choices are non-starters, and will have
to ge greyed out for decades to come. Just in case, I have a setup checkbox
for "assume dual-stream AC-3 decoders." It will be unchecked, and most
likely invisible until there are sets with dual-stream decoders. If ever.
I did note in the candidate spec that this state of affairs is essentially
enshrined in E-AC-3: the now-superflous modes are missing.
And, let's put this in context: soon, ATSC broadcasters will be able to
choose between two (or three) video codecs, but there will be no choice in
audio systems in ATSC transport streams without a modification of the A/53
spec. Why? Because language in A/53 mandates that the AC-3 audio
descriptor be present in EVERY video/audio or audio service in an ATSC
transport stream. A/52 requires that this Ac-3 descriptor match the
characteristics of the actual audio stream. So, that makes AC-3 mandatory.
Any other codec would have to have an advantage after taking this "tax" into
account.
This tax, to the best of my knowledge, is not present in any other system,
save perhaps Australia's.
John Willkie
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Mark Schubin
Sent: Thursday, April 08, 2004 8:46 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: PR: Enhanced AC-3 Audio Specifications Serve
Multiple Applications
> It was Dolby that refused to grant a license for an unlimited number of
> decoders in an ATSC box, which led all STB manufacturers to only include
one
> AC-3 decoder, thus rendering useless almost all of the flexibility built
> into the ATSC standard for audio, including the ability to mix a second
> language dialog channel with a generic music channel, or the ability to
mix
> voice overs inside the STB instead of at the studio.
We are in complete agreement about the problems of single-stream decoders in
ATSC receivers, but I think
you might be off-base in blaming Dolby. They fought for mandatory
dual-stream, and, I think, were willing
to allow the second decoder fee-free. My understanding is that, when they
couldn't get the mandatory
dual-stream status, they did decide to charge for the second but much less
than for the first.
TTFN,
Mark
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