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Stale data at start of audio recording in imx28evk with 3.14 kernel

Question asked by Craig McQueen on Nov 10, 2014
Latest reply on Nov 12, 2014 by Craig McQueen

I'm testing the 3.14.19 kernel on imx28evk, with a Yocto build that uses the linux-fslc kernel provider.

 

I am doing audio recordings through the SGTL5000 driver as such:

 

arecord -D hw:0,1 -f s16 -c 2 -r 16000 -d 5 test.wav

 

(the -d 5 option specifies the recording duration)

 

I'm finding that the first 400-500 ms of the saved data is actually stale data from the end of the previous recording. To see this, do the following:

 

  1. Provide some test audio input in the LINE INPUT jack. E.g. a 100 Hz sine wave, or some music.
  2. Record audio with e.g. arecord -D hw:0,1 -f s16 -c 2 -r 16000 -d 5 test1.wav
  3. Change the test audio input, e.g. a 150 Hz sine wave, or some different music.
  4. Record a new audio file with e.g. arecord -D hw:0,1 -f s16 -c 2 -r 16000 -d 5 test2.wav

 

Observe that the first 400-500 ms of test2.wav contains stale data from the end of the previous recording.

 

Can anyone replicate and confirm this? Can anyone recommend a fix or a bug hypothesis?

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