Return-Path: Message-ID: <6297d67c0605012039x618add3bq2b29b9ad584c609e@mail.gmail.com> From: "Mayank Batra" To: bluez-devel@lists.sourceforge.net Subject: Re: [Bluez-devel] Motorola HT820 audio fidelity In-Reply-To: <44561FB6.5000306@xmission.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_3378_2419123.1146541169538" References: <1146183877.13358.7.camel@pc7.dolda2000.com> <445189C8.6060602@xmission.com> <1146492165.13358.16.camel@pc7.dolda2000.com> <44561FB6.5000306@xmission.com> Sender: bluez-devel-admin@lists.sourceforge.net Errors-To: bluez-devel-admin@lists.sourceforge.net Reply-To: bluez-devel@lists.sourceforge.net List-Unsubscribe: , List-Id: BlueZ development List-Post: List-Help: List-Subscribe: , List-Archive: Date: Tue, 2 May 2006 09:09:29 +0530 ------=_Part_3378_2419123.1146541169538 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Brad, Have a look at the following headset (Sonorix): http://www.assisttechnology.co.uk/documents/Sonorix_Bluetooth_Headset-Pamph= let.pdf It supports both SBC and MP3 codecs. And it is BT1.2 compliant. Mayank On 5/1/06, Brad Midgley wrote: > > Fredrik > > >>It doesn't help that we're typically decoding mp3 and reencoding in sbc= . > >>Loss is really compounded. > > > > > > Indeed, that seems to be the problem. I was always under the > > (uninformed) impression that SBC was lossless, but I just tried > > re-encoding an MP3 to SBC and playing that SBC with sbcenc and sbcdec, > > and the exact same audio artifacts are showing themselves when I play > > back to my normal speaker system as through the headphones. > > You haven't ruled out our implementation of sbc however. We could have > problems still. Also, there are also some defaults for encoding that > although set fairly high are not at the max iirc. > > There is/was a reference SBC encoder that is a windows executable > somewhere at bluetooth.org. Testing with it would let us rule out (or > implicate) our implementation. > > > So, at least it's not a hardware or BT stack problem. Is this an > > inherent problem in SBC, or is there a way to tune the encoder to > > compensate? Is it possibly so that a better encoder could be written > > altogether? > > The spec allows us to negotiate a different codec with the headset. SBC > is the only required codec. fwiw, I've never seen a headset that accepts > mp3 or others. I should modify a2play to flag these so they would be > easier to spot. > > Brad > > > ------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job > easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronim= o > http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D120709&bid=3D263057&dat= =3D121642 > _______________________________________________ > Bluez-devel mailing list > Bluez-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bluez-devel > ------=_Part_3378_2419123.1146541169538 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Brad,
 
Have a look at the following headset (Sonorix):
 
 
It supports both SBC and MP3 codecs.
And it is BT1.2 compliant.
 
Mayank

 
On 5/1/06, B= rad Midgley <bmidgley@xmiss= ion.com> wrote:
Fredrik

>>It doesn'= t help that we're typically decoding mp3 and reencoding in sbc.
>>= Loss is really compounded.
>
>
> Indeed, that seems to be the problem. I was always= under the
> (uninformed) impression that SBC was lossless, but I jus= t tried
> re-encoding an MP3 to SBC and playing that SBC with sbcenc = and sbcdec,
> and the exact same audio artifacts are showing themselves when I p= lay
> back to my normal speaker system as through the headphones.
=
You haven't ruled out our implementation of sbc however. We could have
problems still. Also, there are also some defaults for encoding thatalthough set fairly high are not at the max iirc.

There is/was a re= ference SBC encoder that is a windows executable
somewhere at bluetooth.org. Testing with it would let us rule out (or
implicate) = our implementation.

> So, at least it's not a hardware or BT stac= k problem. Is this an
> inherent problem in SBC, or is there a way to= tune the encoder to
> compensate? Is it possibly so that a better encoder could be writt= en
> altogether?

The spec allows us to negotiate a different c= odec with the headset. SBC
is the only required codec. fwiw, I've never = seen a headset that accepts
mp3 or others. I should modify a2play to flag these so they would beeasier to spot.

Brad


-----------------------------------= --------------------
Using Tomcat but need to do more? Need to support w= eb services, security?
Get stuff done quickly with pre-integrated technology to make your job = easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache= Geronimo
http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D120709&bid=3D263057= &dat=3D121642
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------=_Part_3378_2419123.1146541169538-- ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Bluez-devel mailing list Bluez-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bluez-devel