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Subject: Re: DMA Operation???
From: George Styles \(RipnetUK\) (
Date: 2002-10-19

yeah, if we could even pause the DMA and then reset the frame, then insert
our beep/voice and then re-enable the DMA it may work. WOuld get some
clicks/pops, but maybe not too bad - it may even be that the MAS is quiet
until it gets a valid frame start anyway.

The Speech! program on the BBC B used < 16k of memory and built words from
phonomes, so should be possible to do something similar on Rockbox


----- Original Message -----
From: "Greg Haerr" <>
To: <>
Sent: Friday, October 18, 2002 6:28 PM
Subject: Re: DMA Operation???

> : > I take your point about having to frame align my 'beep', you are quite
> : > correct - bit of a challenge that :) i guess we are looking at doing a
> : > little DMA to finish the current frame before the 'beep' dma,
> : > followed by
> : > the remaining real MP3 frames, including dealing with track boundaries
> : > etc...
> :
> : Yup. Quite a tricky task.
> I was just thinking the other day that this sort of method could be
> used to piece together voice response and other audio, put
> together in memory, thus allowing rockbox to talk.
> So is the issue that we have to frame align any inserted
> data, or can the MAS chip be turned off/reset externally
> and a new frame started?
> I think I need to re-read the MP3 and MAS specs. I'd
> like to help.
> Regards,
> Greg

Page was last modified "Jan 10 2012" The Rockbox Crew