Subject: Re: [Bluez-devel] Motorola HT820 audio fidelity
From: Fredrik Tolf <fredrik@dolda2000.com>
To: bluez-devel@lists.sourceforge.net
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Date: Tue, 09 May 2006 05:20:09 +0200

On Wed, 2006-05-03 at 23:31 -0600, Brad Midgley wrote:
> > Anyway, I tried it, and it was an *enormous* difference. It is true that
> > the file encoded by the encoder from bluetooth.org is almost twice as
> > large as that encoded by sbcenc as well, but nonetheless, the difference
> > in audio quality was huge.
> 
> twice as large? could be they're using 4 subbands.

I don't entirely remember, but I really think it was using 8 subbands
(when checking with sbcinfo).

> maybe our defaults are too lossy. after calling sbc_init, you can change
> sbc.subbands (default 8), sbc.blocks (default 16), sbc.bitpool (default
> 32). subbands can be 4,8. blocks can be 4,8,12,16. i need to check the
> spec on bitpool ranges.

Except the bitpool value, doesn't that mean that it's already using the
best possible values? Or do lower values of sbc.subbands or sbc.blocks
increase quality?

> (heh, maybe that's what you're getting even now)

Indeed. :)

> a2play "sort of" has a flag for choosing encoder settings (-t for
> thrifty) but it is pretty rough.

Again, wouldn't that make the audio quality worse (given how the thrifty
value only decreases the given values)?

Fredrik Tolf


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