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Subject: Re: Iriver: 48kHz Ogg turns on radio?

Re: Iriver: 48kHz Ogg turns on radio?

From: Magnus Holmgren <lear_at_algonet.se>
Date: 2005-07-10

On Sat, 9 Jul 2005 sascha@meta-x.de wrote:

> "Andrew 'ashridah' Pilley" <ashridah@netspace.net.au> writes:
>
> > I've got some 32KHz ogg files that sounded horrible with the resampling.
> > they played at the right speed tho, so the timing is right. There was
> > basically fast static ticking, like there's an off-by-one somewhere and
> > some pcm values aren't being written to, and thus, are coming out as
> > noise, but that's just my uneducated ear's interpretation.
>
> I can confirm that problem. Playing oggs with 32kHz has the noises at
> least since daily 20050703 (and still has them with the bleeding
> 2005-07-09 08:12).

I've been working on the code responsible for the resampling (in dsp.c),
and I must say I'm not entirely surprised. When I looked at how Vorbis
samples were processed (as compared to MP3), I was worried that some
calculations might overflow. Maybe that's what you're hearing?

And no, I don't have any code ready for test now, though making a quick
test for this would be quite easy actually. Anyone inclined could change
dsp.c to shift left 15 rather than 16 bits (and adjust min/max/fracbits
values appropriately). :) Maybe I'll run some tests tomorrow...

Magnus Holmgren

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Received on Sun Jul 10 22:40:12 2005


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