I've just committed my change to the ivtv-0.4 branch. Can you test this?
I'm actually curious to learn whether this might also fix problems with
the old firmware version. Perhaps modifying the sampling rate while the
microcontroller was still running has been the cause all along. No
guarantees though, buggy firmware still seems a very likely cause too.
Please let me know if this works out, in that case I'll also update the
cx25840 in the kernel.
Hans
On Sunday 16 April 2006 12:11, Hans Verkuil wrote:
> Thank you for researching this! It actually makes a lot of sense,
> turning on the microcontroller before calling set_audclk_freq is
> asking for problems. I'll modify cx25840-audio.c and commit it in svn
> for others to test.
>
> Hans
>
> On Sunday 16 April 2006 02:10, Jim Pulokas wrote:
> > Given that the new firmware prevents the bad audio
> > when doing ivtvctl -q0, but not when doing mythtv
> > recordings, I have been studying what mythtv is doing
> > to cause the bad audio.
> > I am using ivtv 0.4.3 for all my tests.
> >
> > I turned on ioctl debugging in ivtv, which shows
> > several ioctls when myth starts recording. I have
> > determined this one to be causing my audio problem:
> > IVTV_IOC_S_CODEC
> > I can now reproduce the problem by repeating the
> > following several times:
> > ivtvctl -cbitrate=6600000
> > (or whatever bitrate you want)
> > This does the IVTV_IOC_S_CODEC ioctl.
> > Just like our previous problem with ivtvctl -q0, this
> > toggles bad audio on and off in a random sort of way.
> >
> > I am trying a very crude hack that seems to fix my
> > problem (may break other stuff though)
> > In cx25840-audio.c, I added a reset of cx25840
> > register 0x803 at the end of the set_audclk_freq
> > function.
> > In other words, before returning from set_audclk_freq,
> > add the following lines:
> > cx25840_and_or(client, 0x803, ~0x10, 0x00);
> > cx25840_and_or(client, 0x803, ~0x10, 0x10);
> >
> > Now I never get bad audio from ivtvctl, and I'm
> > patiently waiting to see if mythtv is also fixed.
> >
> > Also, I tried the recent suggestion regarding
> > newi2c=0, but that did not solve this toggling of bad
> > audio problem.
> >
> > Jim
> >
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