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edt is offline edt
2008-07-11 , 23:45
Posts: 27 | Thanked: 3 times | Joined on Jan 2008
#171
I was able to get a2dp working without too much pain. Just pairing headphones, installing the a2dp-support package (see the first message on this thread) and using the a2dp script to setup and toggle a2dp support on and off worked fine. I then downloaded the three files from the garage to get the dsp based SBC encoder working. After untaring the tar from '/' and running the script (which installs the downloaded .deb) and rebooting it also worked. As expected, CPU is much lower using the dsp based SBC encoder...

Thats the good news.

Most of my videos, which work fine with normal alsa sound, generate no sound with ad2p - my .mp3 files work though. I have noticed that the quality is _much_ better if a wifi connection is not active. It seems that wifi affects bluetooth when using ad2p. Other than that the quality is OK (eg. HSP is much worst) - its not great though. Is this typical or is it a result of the cheap ($60 nokia b501) headphones?

Thanks
Ed
Last edited by edt; 2008-07-12 at 01:00.
 
lardman is offline lardman
2008-07-12 , 08:59
Posts: 2,102 | Thanked: 1,309 times | Joined on Sep 2006
#172
If you're using the DSP task, it drops the ARM CPU speed down to 330MHz, so you may get some sorts of corruption (I've no idea if the audio stream is dropped in preference to the video stream for examaple).
 
TrulsT is offline TrulsT
2008-07-12 , 10:00
Posts: 5 | Thanked: 4 times | Joined on Jan 2008
#173
Originally Posted by edt View Post
I have noticed that the quality is _much_ better if a wifi connection is not active. It seems that wifi affects bluetooth when using ad2p. Other than that the quality is OK (eg. HSP is much worst) - its not great though. Is this typical or is it a result of the cheap ($60 nokia b501) headphones?
I have tried to stream a radio station to my headphones, but it seems that wi-fi really slows down when a2dp is active. The connection is like 0.2mB/s, while i actualy have a 3,5mB/s line. This works perfectly while the headphones is not connected, but it just buffers every second when a2dp is active. And it's not only the tablets that have the problem. My N95 has the same problems while streaming and using a2dp, and my computer too. Everything is connected via wi-fi, so it seems it is interfering with each other (both runs on the 2,4 ghz band).
I tried running a2dp with my phone while trying to use wi-fi on my computer but it worked fine... And it can't be because the cpu is overloaded, since the same problem is on the computer.

Anyone who has any opinion about what is happening? And is there any way i can stream my radio to my bluetooth headset?
 
Seb Per is offline Seb Per
2008-07-12 , 14:07
Posts: 269 | Thanked: 4 times | Joined on Feb 2007 @ Finland
#174
a question from a A2DP dummy: Do the experts think that there is hope to get user friendly and perfect sound quality without too many drawback (cpu, consumption etc) one day?
 
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sachin007 is offline sachin007
2008-07-12 , 14:24
Posts: 2,041 | Thanked: 1,066 times | Joined on Mar 2006 @ Houston
#175
Originally Posted by TrulsT View Post
I have tried to stream a radio station to my headphones, but it seems that wi-fi really slows down when a2dp is active. The connection is like 0.2mB/s, while i actualy have a 3,5mB/s line. This works perfectly while the headphones is not connected, but it just buffers every second when a2dp is active. And it's not only the tablets that have the problem. My N95 has the same problems while streaming and using a2dp, and my computer too. Everything is connected via wi-fi, so it seems it is interfering with each other (both runs on the 2,4 ghz band).
I tried running a2dp with my phone while trying to use wi-fi on my computer but it worked fine... And it can't be because the cpu is overloaded, since the same problem is on the computer.

Anyone who has any opinion about what is happening? And is there any way i can stream my radio to my bluetooth headset?
Well i dont know about this time.... but i last used a2dp with os 2007 when kaju initially supported it. I could stream internet radio via a2dp at that time although there wire minor glitches during streaming... but for most part it was ok. But after the os2008 upgrade to 400mhz... why has the a2dp playback gone backward??
 
lardman is offline lardman
2008-07-12 , 18:19
Posts: 2,102 | Thanked: 1,309 times | Joined on Sep 2006
#176
a question from a A2DP dummy: Do the experts think that there is hope to get user friendly and perfect sound quality without too many drawback (cpu, consumption etc) one day?
I think the DSP task should soon be quite usable at 133MHz (on the DSP) which gives the full 400MHz for the ARM (atm it breaks up a bit more than I would like, I'll have a look at some optimisations next week).

Regarding the sound quality, yes this is also going to be addressed - it is to do with a lack of high accuracy timers (so the samples drift around a bit and make the pitch move about). This is something that is being looked at/addressed by the Bluez folk atm.
 
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sachin007 is offline sachin007
2008-07-12 , 18:32
Posts: 2,041 | Thanked: 1,066 times | Joined on Mar 2006 @ Houston
#177
Originally Posted by lardman View Post
I think the DSP task should soon be quite usable at 133MHz (on the DSP) which gives the full 400MHz for the ARM (atm it breaks up a bit more than I would like, I'll have a look at some optimisations next week).

Regarding the sound quality, yes this is also going to be addressed - it is to do with a lack of high accuracy timers (so the samples drift around a bit and make the pitch move about). This is something that is being looked at/addressed by the Bluez folk atm.
Can you take a guess on how long it will take for end users to start using a2dp with tablets??

I know it is hard to guess.... but i am looking at buying a expensive a2dp heaset next week... what do you advise?
Buy or wait??

Thanks
 
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Johnx is offline Johnx
2008-07-12 , 19:16
Posts: 643 | Thanked: 628 times | Joined on Mar 2007 @ Seattle (or thereabouts)
#178
sachin007: The CPU based A2DP works pretty well now actually. The instructions at the beginning of this thread are still valid...but sometimes it doesn't work. I don't know what causes this. I haven't tracked it down. It does work for me after pairing my headphones following the instructions, then un-pairing, rebooting and re-pairing them. I don't know what fixed it. Anyways, I would advise you to wait and see how A2DP progresses before buying A2DP headphones.
 
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sachin007 is offline sachin007
2008-07-12 , 22:47
Posts: 2,041 | Thanked: 1,066 times | Joined on Mar 2006 @ Houston
#179
Thank you jonx.
I did try the instructions on the first post twice. Both times... kaju just did not evn start playing after toggling a2dp.
In fact everytime i try to follow those steps my mplayer just plays any video in fast forward mode without any sound. I have to reflash to get the normal mplayer back.
But i do remember quite a while back when i tried it did work albiet with lot of skipping. Infact i used the a2dp quite well even with streaming internet radioo on the previous 2007 os.
I am anyway going to purchase the a2dp headset ....i believe you guys can do it.
Just a question.... can you stream internet radio via a2dp?
 
lardman is offline lardman
2008-07-13 , 08:57
Posts: 2,102 | Thanked: 1,309 times | Joined on Sep 2006
#180
Probably can do internet radio via mplayer with alsa output?

If you get a headset, see if you can get one which also supports mp3 encoding, that way you will (eventually, as it's not currently supported by Bluez afaik) be able to listen with zero-decoding/encoding overhead.
 
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