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Subject: Re: AC3 pass through

Re: AC3 pass through

From: Justin Brzozoski <>
Date: Mon, 24 Jul 2006 09:48:06 -0400

From when I was skimming through the chip specs and the code looking
at the possibility of adding digital-in recording (stereo PCM only), I
seem to remember that you could configure the two optical ports to do
direct pass-through and any format or speed should be able to go

In terms of being able to save and replay those bit streams later, you
can do a raw capture of the data up to a certain clock speed, and I
*think* you should be able to spit that back out later assuming you
can find an appropriate clock multiplier to approximate the original
data rate.

Currently, the Rockbox firmware can only use the ports for stereo PCM
data (_at_44100) output. Adding input for the same format wouldn't be
too tough. Adapting it to other clock rates would be medium
difficulty. Adding non-PCM formats is a bit beyond me at the moment.

- Justin B

On 7/24/06, john <> wrote:
> Hi!
> Is AC3 pass through possible with the Iriver 1xx digital out? This
> leads to the more general question: If the Iriver is directly
> connected to an external decoder of any kind, can the internal
> decoding be switched off to save cpu power. In that mode data would
> only be read from HD and sent via the digital link. Of course most
> useful for 5.1 stuff, as I doubt, that an external amplifier with mp3
> decoder exists. And even if it would exist it would run an propietary
> protocol. wouldn`t it, sigh?
> cu
> John
Received on 2006-07-24

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