About bt87x

About bt87x

[Joe Hsu]

Hello:

    I have a bt878 audio device. It can work only at digital 
sample rate 8000HZ from TV tuner source. For this bt878 audio
device, we have modified some source of the kernel module
btaudio. The only difference between the original module and
the modified one is the value of GPIO_DMA_CTL register. And
this new btaudio module works for me.

   Now, I have tried to modify alsa bt87x to work for me.
I add another pci_device_id to represent 8000HZ sample rate. I changed
three fields of snd_bt87x_digital_hw
to represent mono 8000HZ. But still don't work. And then
I changed the value of GPIO_DMA_CTL register as I did
in the btaudio module. Well, it worked in slow motion
when I played the captured pcm data. Can somebody
give me some hints? Thanks 

--
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Re: About bt87x

[Clemens Ladisch]

Joe Hsu wrote:
>     I have a bt878 audio device. It can work only at digital
> sample rate 8000HZ from TV tuner source. For this bt878 audio
> device, we have modified some source of the kernel module
> btaudio. The only difference between the original module and
> the modified one is the value of GPIO_DMA_CTL register.

Which field has to be changed?  Is it the physical format of samples
on the serial bus?

>    Now, I have tried to modify alsa bt87x to work for me. I add
> another pci_device_id to represent 8000HZ sample rate. I changed
> three fields of snd_bt87x_digital_hw to represent mono 8000HZ. But
> still don't work.

Those changes wouldn't affect the control register.

> And then I changed the value of GPIO_DMA_CTL register as I did in
> the btaudio module. Well, it worked in slow motion when I played
> the captured pcm data.

This indicates that the actual sample rate is higher than 8 kHz.  Or
probably some stereo/mono mismatch.


Could you please post your changes to btaudio.c?


Regards,
Clemens



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Re: About bt87x

[Joe Hsu]

On Wed, 9 Mar 2005 13:13:21 +0100 (MET), Clemens Ladisch
<clemens@ladisch.de> wrote:
> > And then I changed the value of GPIO_DMA_CTL register as I did in
> > the btaudio module. Well, it worked in slow motion when I played
> > the captured pcm data.
> 
> This indicates that the actual sample rate is higher than 8 kHz.  Or
> probably some stereo/mono mismatch.
> 
> Could you please post your changes to btaudio.c?
> 
> Regards,
> Clemens
> 
> 

btaudio.c is version 0.6 for linux kernel 2.4.x
btaudio2.c is the modified version
btaudio.diff is the difference of btaudio.c and btaudio2.c

When I use btaudio2.c as the btaudio.o module, I load it with 
"insmod btaudio.o analog=0  digital=1 rate=8000".

http://bill-goldberg.myweb.hinet.net/btaudio.c
http://bill-goldberg.myweb.hinet.net/btaudio2.c
http://bill-goldberg.myweb.hinet.net/btaudio.diff


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