[LAU] Bluetooth A2DP pitch shifting

[Robin Paulson]

On 7 April 2011 07:04, Ken Restivo <ken at restivo.org> wrote:
> I have been lately using a Bluetooth A2DP headset to listen to music.
>
> Every now and then, it drops pitch! It slows the music down, by as much as a semitone, for several seconds, then comes back slowly. I rather like the effect; it's like an old cheap analog vynil turntable with a bad motor or worn belt.
>
> What could be causing this? The signal path is Ogg Vorbis files to Android phone (obligatory Linux content!) to A2DP stereo headset.

i'd take a punt that this is a best-effort (as opposed to time
guaranteed) protocol - i.e. "we will get the data there, no guarantees
when" and that something else is taking priority. the a2dp article on
wikipedia talks of using QoS to get better audio delivery, so maybe
that's your answer?

i imagine a2dp was only ever designed to transmit low-bandwidth audio
like phone calls/poor quality mp3 - are you playing a high bitrate
file?

anyway, that's my 'inferred guess' answer

-- 
robin

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