Re: Sound issue with stk1160 driver

[Evgeny Sagatov <sagatov@xxxxx>]

The stk1160 driver has a problem with AC97 codec.
Look at this picture http://sagatov.net/temp/sound-wave.png
In the picture only the right audio channel connected. But for a fraction of a second channels are swapped.
Please tell any ideas why this might happen?

This driver source code, which is responsible for the sound. It is short. May be specified any invalid parameter? http://lxr.free-electrons.com/source/drivers/media/usb/stk1160/stk1160-ac97.c
Please help those who are understands the AC97 codec programming.

Data is not lost. But the audio channels are reversed.

03.02.2014, 17:26, "Evgeny Sagatov" <sagatov@xxxxx>:
> Dear Sirs,
>
> I have EasyCAP device with STK1160+GM7113C+ALC101 chips.
> On my Ubuntu 12.04 with 3.11.0 kernel video capturing functioned perfectly, but audio capturing have problem with sound clicks.
> You can hear these sounds in the linked audio file (Initially both audio inputs enabled and then I mute one, then both audio inputs.).
> http://sagatov.net/temp/audio.wav
> Clearly audible clicks in the headphones. A feeling that for a moment left and right channels are swapped.
> I tested three devices on three computers. I also tested the device on a freshly installed Ubuntu 13.10. But the result is the same everywhere.
> In MS Windows no clicks.
>
> I have tried to boot my Ubuntu 12.04 with the 3.2.0-58 kernel.
> Turned out that the legacy driver is already installed. Probably it is included in Ubuntu distribution.
> I have a beautiful sound in this case without any problems.
> But I have a problem with the video :-) The video is displayed few seconds, and then the gray bars (see picture in the attachment).
>
>>   What kind of video/audio source are you using to trigger this noise?
>>   Do you get the noise on all captures or only on some of them?
>
> I tried two different cameras and video player. Also I tried to leave inputs unconnected.
> Noise is always, regardless of the source.
>
> Noise is better heard when only one audio channel is connected. A feeling that for a split second sound goes to another channel and back.
>
> Earlier I have the correspondence with the developer of stk1160 driver and that the information he sent to me.
>
> 03.02.2014, 16:37, "Ezequiel Garcia" <elezegarcia@xxxxxxxxx>:
>
>>   Hi,
>>
>>   Yesterday I spent all the day debugging this issue. The noise you report
>>   is also present on any capture I do. In fact, I noticed it in the past but never
>>   cared.
>>
>>   Bad news are I still don't have a clue about it.
>>
>>   Let me explain you the differences between stk1160 and easycap audio.
>>   stk1160 depends on a separate ac97-mixer driver to setup the AC97
>>   parameters and on the snd-usb-audio driver to handle the audio stream.
>>
>>   easycap does both things by itself.
>>
>>   Since I'm out of specific ideas, I'll try to implement the audio
>>   handling in stk1160 (just as easycap does) and see what happens.
>>   However, it's not a simple task and it might take a few days/weeks.
>>
>>   For now, you can use the easycap setting easycap_bars = 0 parameter
>>   to avoid those bars. I'm sorry for this regression!
>>
>>   In addition, you can help by taking care of the bug report. This should
>>   be reported to the linux-sound mailing list:
>>   http://vger.kernel.org/vger-lists.html#linux-sound
>>
>>   The problem must be either in snd-usb-audio or in the sound/pci/ac97/..
>>   code. If you can report this (put me on Cc), it would be of great help.
>>
>>   Thanks again and sorry for this inconvenience,
>>   Ezequiel
>
> I hope very much for your help in solving this problem.
>
> Thank you!
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