Re: [LAU] Google TV device w/ AV out

On Thu, July 4, 2013 9:40 pm, Jeremy Jongepier wrote:
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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@email-addr-hidden:~$ 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.

Have you been using this for testing at low latency?

> But I got
> one step further:
>
> jeremy@email-addr-hidden:~$ 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 :)
>

Nicely done!

What was the blocker in the end?

--
Patrick Shirkey
Boost Hardware Ltd
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