cx88-alsa audio quality?

cx88-alsa audio quality?

[Vanessa Ezekowitz]

I forget if I've already mentioned this yet...

I recently started playing around with analog NTSC television again on my system, while trying to help someone solve a problem on their system.  In the process I ran into a problem getting cx88-alsa to build with the rest of the v4l-dvb repository.  As it turned out, mine was one of the stock Ubuntu kernels that have some odd issue with the I2C configuration.   I had to build a vanilla kernel (2.6.26.5), making all the I2C stuff into modules as opposed to built-in.  So, that's fixed - cx88-alsa builds and loads OK now.

However, I have a new problem:

Something has broken the output that cx88-alsa creates.  In the case of my Kworld ATSC 120, radio output on all frequencies has a sort of growling "industrial" noise on top of the actual audio, kinda like the background noise of a manufacturing facility.

Analog TV on all channels gives clean but very tinny audio, as though the sample rate were really low (~8kHz).

Since other audio sources are working fine, I can't tell if this is a bug in the kernel, or cx88-alsa, or something else entirely.  I've only noticed the problem for a matter of a week or less, so I'm not sure when it started.  The problem persists as of today's pull of the v4l-dvb repository.

-- 
"Life is full of positive and negative events.  Spend
your time considering the former, not the latter."
Vanessa Ezekowitz <vanessaezekowitz@gmail.com>

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Re: [linux-dvb] cx88-alsa audio quality?

[Anders Semb Hermansen]

Vanessa Ezekowitz wrote:
> Analog TV on all channels gives clean but very tinny audio, as though
 > the sample rate were really low (~8kHz).

I use a cx88 card (HVR-4000) with Analog TV (PAL). I needed to set audio 
to 48000Hz to get sound which is good. I use mythtv.

English is not my native language so I don't know how to describe the sound.


Anders

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Re: [linux-dvb] cx88-alsa audio quality?

[yoshi watanabe]

i have similar problem with cx88-alsa on hvr-1300 card.

i've been using it to connect playstation2 console to my pc via a
cable with both s-video and composite connectors.

while the video is in good quality,  the sound sounds metallic and
ofter with a very strong reverb. most of the time it's just random
noise.

sometimes it seems to pick up when there is more movement in the
video. when the picture gets still - the noise nearly goes away.

so far i have not found a solution to my problem (i've already asked
on this mailing list for help few months ago, maybe you'll find some
clues that will help you) , other than routing audio to the soundcard
via additional cables, and not taking it though the capture card.
changing sampling rates helps a bit.

hardware mpeg2 capture has perfect audio, however.

i suspected that my pc might be creating some sort of interference.
but that doesn't explain why mpeg2 capture is unaffected by it.

oh, and i cannot find any channels on analog tv. i hope that at least
radio will work (never tried it).

On 9/29/08, Anders Semb Hermansen <anders@ginandtonic.no> wrote:
> Vanessa Ezekowitz wrote:
>> Analog TV on all channels gives clean but very tinny audio, as though
>  > the sample rate were really low (~8kHz).
>
> I use a cx88 card (HVR-4000) with Analog TV (PAL). I needed to set audio
> to 48000Hz to get sound which is good. I use mythtv.
>
> English is not my native language so I don't know how to describe the sound.
>
>
> Anders
>
> _______________________________________________
> linux-dvb mailing list
> linux-dvb@linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
>

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Re: [linux-dvb] cx88-alsa audio quality?

[Mauro Carvalho Chehab]

On Mon, 29 Sep 2008 01:01:51 -0500
Vanessa Ezekowitz <vanessaezekowitz@gmail.com> wrote:

> I forget if I've already mentioned this yet...
> 
> I recently started playing around with analog NTSC television again on my system, while trying to help someone solve a problem on their system.  In the process I ran into a problem getting cx88-alsa to build with the rest of the v4l-dvb repository.  As it turned out, mine was one of the stock Ubuntu kernels that have some odd issue with the I2C configuration.   I had to build a vanilla kernel (2.6.26.5), making all the I2C stuff into modules as opposed to built-in.  So, that's fixed - cx88-alsa builds and loads OK now.
> 
> However, I have a new problem:
> 
> Something has broken the output that cx88-alsa creates.  In the case of my Kworld ATSC 120, radio output on all frequencies has a sort of growling "industrial" noise on top of the actual audio, kinda like the background noise of a manufacturing facility.
> 
> Analog TV on all channels gives clean but very tinny audio, as though the sample rate were really low (~8kHz).
> 
> Since other audio sources are working fine, I can't tell if this is a bug in the kernel, or cx88-alsa, or something else entirely.  I've only noticed the problem for a matter of a week or less, so I'm not sure when it started.  The problem persists as of today's pull of the v4l-dvb repository.
> 

This may be due to some issue at alsa libraries or at pulseaudio. On some tests
I did with alsa, depending on the way you specify a device, you may have
noise (I had lots of noise on my alsa microphone input, depending on the syntax
I used to specify its input entry). You may specify it as hw: or as plughw:. The
difference between them is the way libalsa will handle it, and what is
specified on your alsa config files.

Cheers,
Mauro

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