FW: REALLY Bad encoding performance of Linux SBC audio codec

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Hello Frans,

 

thank you for the patch!!

 

Christian

 

 

From: Frans de Bont [mailto:frans.de.bont@xxxxxxxxxxx]
Sent: Thursday, October 30, 2008 2:34 PM
To: Christian Hoene
Subject: RE: REALLY Bad encoding performance of Linux SBC audio codec

 


Hello Christian,

I had a quick look into the bluez sbc decoder test application.
I discovered that the buffering was not correct.
Attached a modified version.

Please note that the output level of the decoder is still 6 dB too low.
This wouldn't be too difficult to fix for the bluez developers.

Best regards,
Frans







"Christian Hoene" <hoene@xxxxxxxxxxxxxxxx>

2008-10-29 04:30 PM

To

"'BlueZ development'" <bluez-devel@xxxxxxxxxxxxxxxxxxxxx>

cc

Frans de Bont/EHV/APPTECH/PHILIPS@PHILIPS

Subject

RE: REALLY Bad encoding performance of Linux SBC         audio codec

Classification

 




Hello,

Sorry Bad news.
the encoding and decodng performance of bluez's SBC is really bad.
I just used the latest sbcenc program from bluez-4.17 and compared it to the
reference

Attached you will find wav-files encoded with the Bluetooth reference
implementation and bluez

Filelist
========
compare.sh                         is the scrip that I use to compare both codec
versions
refsop01.wav        the original sample
tmp.ref.sbc         with reference encoded
tmp.bluez.sbc       with bluez encoded
tmp.ref.sw.wav      with reference encoded and decoded (has good quality)
tmp.bluez.sw.wav    with bluez encoded and decoded (has bad quality ODG=)
tmp.refbluez.sw.wav with reference encoded and with bluez decoded (has bad
quality)
tmp.bluezref.sw.wav with bluez encoded and with reference decoded (has
medium quality)

Both the bluez encoder and decoder do not work as good as the reference
implementation.

I also conducted some perceptual audio tests with ITU BS.1387 (PEAQ), which
confirm these results.

With best regards,

Christian

PS:
Attached also an enhanced version for sbc/sbcenc.c, which considers more
command line options.



> -----Original Message-----
> From: Marcel Holtmann [mailto:marcel@xxxxxxxxxxxx]
> Sent: Monday, October 27, 2008 8:42 PM
> To: BlueZ development
> Subject: Re: Bad encoding performance of Linux SBC audio
> codec
>
> Hi Brad,
>
> > > I am sorry to say that the audio quality of the open source version
> of SBC
> > > is far worse than the reference implementation.
> >
> > If you are using the standalone "sbc" project at sourceforge, then
> you
> > should try the version inside bluez. The standalone used to simply be
> > slower, but we identified & fixed some quality issues too that should
> > be backported.
>
> the standalone version should not be used at all at the moment. All
> efforts should go into the version included in bluez-4.x.tar.gz.
>
> Regards
>
> Marcel
>
>
>
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[attachment "sbcenc.c" deleted by Frans de Bont/EHV/APPTECH/PHILIPS] [attachment "compare.tar.gz" deleted by Frans de Bont/EHV/APPTECH/PHILIPS]

Attachment: sbcdec.c
Description: Binary data

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