Android NDK OpenSL Buffer Sample and Noise Crackle

[umut caliskan]

Hi,

i am developing a recording and playing audio android sample application.

I have a samsung galaxy nexus. 

I m using opensl and use a circular buffer implementation from Victor Lazzarini's sample. (http://audioprograming.wordpress.com/)

I saw the buffer samples of my phone is 144 and it has 44100 sampling rate.

When i set the buffer sample equal to 144 and sample rate 44100, Output sound crackle  and distorting sound.

when i was buffer sample equals to 1200 +, i heard normal sound  but latency occurs..

Do you have any idea? What is the optimum sample rate and buffer samples. Or any sample other real time audio processing like recording and playing?

[Glenn Kasten]

Sorry for my delay in replying. Which software build are you on?

  (I think you can get this from Settings / About phone)

Can you please include the output of shell command

  dumpsys media.audio_flinger

(this command now includes statistics that may help to

understand the noise, but I'm not sure if your build includes the statistics)

[umut caliskan]

Hi Glenn, thanks for reply.

i run the Audio Buffer Size app from store and run this app. The result is; sample rate 44.1kHz and buffer size :144

My system is build on Android 4.2.2 version, BaseBand version : I515.10 V.FK01 /  I515.10 V.FK02 ,

Kernel version 3.0.31 g9f818de andro...@vpbs1.mtv.corp.google.com #1 and build numberJDQ39

i run this command  adb shell media.audio_flinger and output is :

Clients:

  pid: 378

  pid: 567

Global session refs:

 session pid count

       6 567   1

    1337 378   1

    1338 378   1

    1339 378   1

    1901 378   1

    2004 378   1

Hardware status: 0

Standby Time mSec: 3000

Output thread 0x41bb2370 internals

last write occurred (msecs): 179294

total writes: 385626

delayed writes: 0

blocked in write: 0

suspend count: 0

mix buffer : 0x41bba608

Fast track availMask=0x40

io handle: 2

TID: 398

standby: 1

Sample rate: 44100

HAL frame count: 144

Normal frame count: 864

Channel Count: 2

Channel Mask: 0x00000003

Format: 1

Frame size: 4

Pending setParameters commands: 

 Index Command

Pending config events: 

AudioMixer tracks: 0000005f

FastMixer command=COLD_IDLE writeSequence=4629472 framesWritten=333321984

          numTracks=1 writeErrors=0 underruns=151604 overruns=27308

          sampleRate=44100 frameCount=144 measuredWarmup=76.3 ms, warmupCycles=2

          mixPeriod=3.27 ms

Simple moving statistics over last 3.1 seconds:

  wall clock time in ms per mix cycle:

    mean=3.26 min=0.09 max=6.65 stddev=1.10

  raw CPU load in us per mix cycle:

    mean=194 min=0 max=397 stddev=55

Fast tracks: kMaxFastTracks=8 activeMask=0x1

Index Active Full Partial Empty  Recent Ready

    0    yes  531       0   134    full  1440

    1     no    0       0     0    full     0

    2     no  507       0   250   empty     0

    3     no  134       2   779   empty     0

    4     no  283       0   805   empty     0

    5     no  536       0   142   empty     0

    6     no  478       0   337   empty     0

    7     no  665       1   782   empty     0

State queue observer: stateChanges=6449

State queue mutator: pushDirty=6449 pushAck=3224 blockedSequence=748

Output thread 0x41bb2370 stream volumes in dB:

    0:-18, 1:-24, 2:-21, 3:-37, 4:-14, 5:-6, 6:0, 7:-24, 8:-18, 9:-37

Output thread 0x41bb2370 tracks

   Name Client Type Fmt Chn mask   Session mFrCnt fCount S M F SRate  L dB  R dB    Server      User     Main buf    Aux Buf  Flags Underruns

   F  2    378    1   1 0x00000001    1339    144   3456 S 0 1 44100  -Inf  -Inf  0x00000000 0x00000000 0x41bba608 0x00000000  0x83         0 

   F  5    378    1   1 0x00000001    1337    144   3456 S 0 1 44100  -Inf  -Inf  0x00000000 0x00000000 0x41bba608 0x00000000  0x83         0 

   F  3    378    1   1 0x00000001    1901      4   3456 S 0 1 44100  -Inf  -Inf  0x00000000 0x00000000 0x41bba608 0x00000000  0x83         0 

   F  4    378    1   1 0x00000001    1338    144   3456 S 0 1 44100  -Inf  -Inf  0x00000000 0x00000000 0x41bba608 0x00000000  0x83         0 

   F  1    567    0   1 0x00000001       6      0    288 I 0 0 44100   -10   -10  0x00000000 0x00000000 0x41bba608 0x00000000  0x8b         0 

   F  7    378    1   1 0x00000001    2004    144   3456 S 0 1 44100  -Inf  -Inf  0x00000000 0x00000000 0x41bba608 0x00000000  0x83         0 

Output thread 0x41bb2370 active tracks

   Name Client Type Fmt Chn mask   Session mFrCnt fCount S M F SRate  L dB  R dB    Server      User     Main buf    Aux Buf  Flags Underruns

Normal mixer raw underrun counters: partial=0 empty=134

- 0 Effect Chains:

Output thread 0x41bc6cf8 internals

last write occurred (msecs): 171439719

total writes: 0

delayed writes: 0

blocked in write: 0

suspend count: 0

mix buffer : 0x41bcef90

Fast track availMask=0xfe

io handle: 3

TID: 399

standby: 1

Sample rate: 44100

HAL frame count: 976

Normal frame count: 976

Channel Count: 2

Channel Mask: 0x00000003

Format: 1

Frame size: 4

Pending setParameters commands: 

 Index Command

Pending config events: 

AudioMixer tracks: 00000000

FastMixer not initialized

State queue observer: stateChanges=0

State queue mutator: pushDirty=0 pushAck=0 blockedSequence=0

Output thread 0x41bc6cf8 stream volumes in dB:

    0:-10, 1:-22, 2:0, 3:-22, 4:-4.5, 5:-26, 6:0, 7:-22, 8:-22, 9:-22

Output thread 0x41bc6cf8 tracks

   Name Client Type Fmt Chn mask   Session mFrCnt fCount S M F SRate  L dB  R dB    Server      User     Main buf    Aux Buf  Flags Underruns

Output thread 0x41bc6cf8 active tracks

   Name Client Type Fmt Chn mask   Session mFrCnt fCount S M F SRate  L dB  R dB    Server      User     Main buf    Aux Buf  Flags Underruns

Normal mixer raw underrun counters: partial=0 empty=0

- 0 Effect Chains: