asvravi at gmail
Jul 18, 2009, 5:34 PM
On Sun, Jul 19, 2009 at 12:30 AM, Ravi A<asvravi [at] gmail> wrote:
Re: Fwd: [UNKNOWN IVTV CARD] (cx23416) AverMedia M113-C
[In reply to]
>>> > When MUX is set properly and sound is present, the volume was still a
>>> > bit low and it seemed very noisy - something like zero-crossing
>>> > distortion. I could improve it a bit by setting volume all the way
>>> > high.
>>> > sudo v4l2-ctl -c volume=65535
>>> > Setting bass and treble to '0' helped to reduce the distortion/noise
>>> > significantly although the volume still seemed low
>>> > sudo v4l2-ctl -c bass=0
>>> > sudo v4l2-ctl -c treble=0
>>> > If I can get v4l2-dbg to read/set registers maybe I can try more
>>> > experiments for the audio quality.
>> Yes, it will give you the flexibility to experiment will all sorts of
>> audio settings.
> Hi Andy,
> With the latest patch, the MUX control becomes stable and the audio
> stays put with video standard changes!
> Now that the audio is stable, I notice some possible issue with the
> PLL VCO center frequency adjustment patch. Both e8fcd13e4ae7 and
> d7e1eb4b17d8 show some skips/gaps in both video and audio (Composite
> input). After 10 seconds of playing with mplayer the following is
> output -
> "Your system is too SLOW to play this! .. blah"
> and after another 10 seconds a continuous stream of "Too many video
> packets in the buffer: (4096 in 8007268 bytes)... blah" appear.
> Patches 82a264ea2784 and 7ea3e7b9a657 do not show this, both video and
> audio are smooth.
> I was able to finally read some registers after compiling the latest
> v4l2-dbg. I will try tweaking audio registers using 82a264ea2784 next.
I experimented with the audio register settings on CX25840. I could
not seem to program the WM8739 though, there is no response with
$ sudo ./v4l2-dbg -c wm8739 -s 0x1a 0x80
And since wm8739 does not support register readback, I was not able to
verify the register settings.
Anyway, on the CX25840, increasing the volume and equalizers helped to
improve the SNR. I wish the this can be done on the WM8739 instead in
front of the ADC, so that the line level input signal (usually 320mV)
gets gained up to ADC input range of 1Vrms. Also note that there are
attenuating resistors in the signal path at input of WM8739, so the
gain may need to compensate for this too. Let me know if I am
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