Re: [Bluez-devel] Quality of a2dp sound

[Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hi Marcel !

Marcel Hilzinger schrieb:
> Hi,
> =

> I made some tests with bluetooth stereo headsets and a2dpd. =

> I must confess, I'm impressed by the easy use of a2dpd! Thanks, it's just =

> great. =


Yes, the usage is very simple, indeed. Once I figured out how to use
passkey-agent, the connection worked immediately ;).

> =

> But I'm not impressed by the audio quality. Its quite noisy and far away =
from =

> the quality of normal wireless headphones. Headset was a Jabra BT620s. I =

> tried with different dongles, but the dongle seems to make no difference.

My problem with the audio quality and a2dpd is, that the quality is set
to telephone quality only (8kHz, Mono) though my headset can do up to
44,1kHz Stereo (SONY VGP-BRM1D) and a2dpd even displays 44,1kHz. When
using a2play I can listen in 44,1kHz quality, so this is an issue with a2dpd
for me (but a2play plays the MP3s with higher speed, so they sound
high-pitched). Also the sound is chopped very often with a2dpd, so this is =
no use for me
at the moment :(.

> =

> Questions: =

> is this a problem of the technology?

I don't think so, this is rather due to the fact that btsco is still in
Alpha status of development.

> is it a problem of bluez?

No, I'd rather blame btsco. (I tried different kernel versions, 2.6.17.9
and 2.6.19-rc5 and the most recent bluez-utils version).

> did I something wrong?

Have you tried a2play instead ? Do this:

- hcitool scan
- passkey-agent <code> <address>
- btsco -r -v <address>
- mpg123 --au - file.mp3 | a2play <address>

> =

> did anybody compare the quality on Windows? I tried to compare with Mac. =
But =

> as Mac OS X cannot do a2dpd, it's even worse on Mac.


I was not able to use my headset in Windows, Windows doesn't give me any
options for choosing the headset as an audio output-device, though I can
to the headset successfully. On 2 Macintosh Mini (Intel and PPC) with OS 10=
.4
I was able to connect to the headset without any problems, and I could
choose my headset for all the sound-output so I was able to listen to
iTunes via the headset. The only drawback on the Mac is, that the
quality is limited to 8000Hz, 16 Bit mono (and the Audio Utility won't
let me choose any better quality, though the headset supports this).

> =

> Regards,
> -- =

> =DCdv=F6zlettel -- Mit freundlichen Gr=FCssen,
> Marcel Hilzinger


Greetings,

Adrian

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