[LAU] Google TV device w/ AV out

Jeremy Jongepier jeremy at autostatic.com
Thu Jul 4 11:40:54 UTC 2013


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On 07/01/2013 05:16 PM, Patrick Shirkey wrote:
> 
> On Tue, July 2, 2013 12:44 am, Jeremy Jongepier wrote:
>> On 07/01/2013 04:12 PM, Patrick Shirkey wrote:
>>> IIUC the potential issues with period sizes with non powers of
>>> two are at the application level. JACK is agnostic about it.
>>> 
>> 
>> Yes, guitarix for instance doesn't like period sizes that are not
>> a power of two.
>> 
>>> Anyway it's a little spooky that you get better performance
>>> with -p64 than -p128 even in playback only mode.
>> 
>> Well I'm testing and haven't done any real stress-tests yet.
>> Maybe it was a one-off. At least I get undistorted sound out of
>> this device. Now if I could only figure out why JACK bails out
>> every once so often.
> 
> Does this happen with or without wifi enabled?
> 
>> And why full-duplex doesn't work, well, it works but the audio
>> coming out is distorted.
>> 
> 
> System load causing distortion on the Audio device in duplex mode.
> It suggests something is wrong with the bus and or interrupts but I
> don't see why it would be ok in playback only mode. Not sure if it
> is related but I have noticed that my old usb quattro often takes a
> while to warm up. Sometimes I have to run it for a few hours and
> start/stop jack several times to get undistorted output.
> 
> Another issue is the Rockchip devs probably haven't tested the
> device at low latency with duplex mode so they haven't picked up
> that issue. We can try flagging it with them.
> 
> I forgot what the audio chipset is. Can you post the output of cat 
> /proc/asound/cards?
> 

jeremy at rk3066:~$ cat /proc/asound/cards
 0 [RK29RK1000     ]: RK29_RK1000 - RK29_RK1000
                      RK29_RK1000
 1 [HDMI           ]: ROCKCHIP_HDMI - ROCKCHIP HDMI
                      ROCKCHIP HDMI
 2 [Device         ]: USB-Audio - Generic USB Audio Device
                      Generic USB Audio Device at usb-usb20_host-1.1,
full speed

'Device' is a $2 USB audio interface with a C-Media chipset. But I got
one step further:

jeremy at rk3066:~$ uname -a
Linux rk3066 3.0.36-rt58 #1 SMP PREEMPT RT Thu Jul 4 13:18:23 CEST
2013 armv7l GNU/Linux

So I've got a RT kernel running on it. Moving on :)

Jeremy

> 
> 
> 
> -- Patrick Shirkey Boost Hardware Ltd 
> _______________________________________________ Linux-audio-user
> mailing list Linux-audio-user at lists.linuxaudio.org 
> http://lists.linuxaudio.org/listinfo/linux-audio-user
> 

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