Message-ID: <4583A020.2040808@xmission.com>
Date: Sat, 16 Dec 2006 00:28:32 -0700
From: Brad Midgley <bmidgley@xmission.com>
MIME-Version: 1.0
To: BlueZ development <bluez-devel@lists.sourceforge.net>
References: <44F6B7AE.1030209@jambit.com> <4582A310.60905@jambit.com>
In-Reply-To: <4582A310.60905@jambit.com>
Cc: frank.heimbaecher@jambit.com
Subject: Re: [Bluez-devel] [Bluez-users] How to use sbc.c of btsco?
Reply-To: BlueZ development <bluez-devel@lists.sourceforge.net>
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Frank

fyi, I moved the reply to bluez-devel.

> sbc_encode: It seems like you put pcm data on 'data' and get sbc data in
>  'sbc.data'. 'count' is not used in the function. How often must I call
> it? How do I know how much of 'data' is converted already?

the return value from sbc_encode is the number of bytes consumed. It's 
true that count is not used properly. In fact we assume there is enough 
data there to fill one sbc frame.

> sbc_decode: Put sbc data on 'data' and you get pcm data in 'sbc.m.data'.
> Is that right? Must I always change the byte order like it is done in
> a2recv.c?

The swapping was to accommodate bugs in the audio driver's endian 
processing on gumstix. You can ignore it.

> Are there special things to do if I have a .wav file or do I just have
> to call the functions? I am just talking of the payload and not the headers.

be sure you init the encoder with the correct channels (1 or 2) and 
sample rate. after that just be sure to pass enough data to sbc_encode 
in each pass so it doesn't underrun.

> It would help me a lot if somebody could put me on the right track.

Be sure you are using the separate sbc sourceforge project since that's 
the version of the codec we are maintaining. Finally, we'd appreciate 
any patches you come up with to improve the code documentation or even 
more if you address any of the limitations. Documentation of course is a 
problem, but there's also a todo list at the top of sbc.c.

Brad

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