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A2DP probably using SBC instead of MP3 codec

1,860 posts
Thanks Meter: 15
 
By jashsu, Senior Member on 29th May 2009, 07:01 AM
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Some top logs:

Music open, no songs playing:

Code:
User 8%, System 6%, IOW 0%, IRQ 0%
User 27 + Nice 0 + Sys 21 + Idle 287 + IOW 0 + IRQ 0 + SIRQ 0 = 335

  PID CPU% S  #THR     VSS     RSS UID      Name
  290   3% S     9 108100K  15892K app_13   com.android.music
  807   3% R     1    904K    364K root     top
Music open, MP3 playing on speaker:

Code:
User 19%, System 7%, IOW 0%, IRQ 0%
User 61 + Nice 0 + Sys 23 + Idle 233 + IOW 0 + IRQ 0 + SIRQ 0 = 317

  PID CPU% S  #THR     VSS     RSS UID      Name
   37  21% S    15  35524K   3120K media    /system/bin/mediaserver
  811   4% R     1    904K    364K root     top
Music open, MP3 playing on A2DP:

Code:
User 33%, System 5%, IOW 0%, IRQ 0%
User 107 + Nice 0 + Sys 18 + Idle 195 + IOW 0 + IRQ 0 + SIRQ 0 = 320

  PID CPU% S  #THR     VSS     RSS UID      Name
   37  33% S    15  35508K   3088K media    /system/bin/mediaserver
  806   4% R     1    908K    376K root     top
The mediaserver process consumes approximately 10-12% more CPU when A2DP is on. My suspicion is that Android 1.5 is transcoding the MP3s to SBC (subband codec) after all. It is possible of course it is transcoding MP3 to MP3, but it would make more sense to just pass the MP3 bitstream directly through to the headset to decode. Also found this in a /etc config file:

Code:
# Configuration file for the bluez audio plugin (A2DP)

[General]
Enable=Source,Control,Sink
Disable=Headset,Gateway

# Switch to master role for incoming connections (defaults to true)
#Master=true

# Just an example of potential config options for the other interfaces
[A2DP]
SBCSources=1
MPEG12Sources=0

[AVRCP]
InputDeviceName=AVRCP
16th October 2009, 12:07 PM |#2  
Junior Member
Thanks Meter: 0
 
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Does anyone know whether this will be improved in the next Android release?
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