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imx6q, issues i2s redirected to HDMI

Question asked by Angelo Dureghello on May 18, 2016
Latest reply on May 24, 2016 by Angelo Dureghello

Hi all,

 

i have the need to play some audio coming from an i2s source (a radio fm) into hdmi card output.

 

i am using a simple alsa loop command as:

arecord --rate=48000 --device=sysdefault:CARD=imxaudiosi4745 -B 8000 -F 1000 | aplay --device=sysdefault:CARD=imxhdmisoc

And a simple hdmi CEA setup as below:

mxc_sdc_fb fb.28: 640x480 h_sync,r,l: 96,16,48  v_sync,l,u: 2,10,33 pixclock=25174000 Hz

 

On kernel 3.10.17 (from boundary) the loop plays fine for minutes.

On more recent kernel 3.14.28, i get some underrun messages here and there, after 10 to 40 seconds, and audio is interrupted from some small holes, or fully interrupted sometime.

 

arecord --rate=48000 --device=sysdefault:CARD=imxaudiosi4745 -B 8000 -F 1000 | aplay --device=sysdefault:CARD=imxhdmisoc

 

Recording WAVE 'stdin' : Unsigned 8 bit, Rate 48000 Hz, Mono

Playing WAVE 'stdin' : Unsigned 8 bit, Rate 48000 Hz, Mono

si4745-codec si4745-codec.355: si4745 codec, setting sample rate as 48000

overrun!!! (at least 0.044 ms long)

overrun!!! (at least 0.870 ms long)

overrun!!! (at least 0.011 ms long)

 

I don't see btw issues playing a wav file directly to hdmi, so it is like some issue in the i2s->hdmi conversion.

 

Was some similar issue knows ?

What do you suggest to do know (can't switch to other kernel versions now) ?

 

Many thanks

angelo

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