Re: cx18: "missing audio" for analog recordings

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Andy Walls wrote:
On Sat, 2010-04-10 at 23:21 -0400, Mark Lord wrote:
On 10/04/10 06:54 PM, Andy Walls wrote:
Hmmm.  Darren's having problems (loss of video/black screen) with my
patches under my cx18-audio repo, but I'm not quite convinced he doesn't
have some other PCI bus problem either.

Anyway, my plan now is this:

1. on cx18-av-core.c:input_change()
	a. set register 0x808 for audio autodetection
	b. restart the format detection loop
	c. set or reset a 1.5 second timeout

2. after the timer expires, if no audio standard was detected,
	a. force the audio standard by programming register 0x808
		(e.g. BTSC for NTSC-M)
	b. restart the format detection loop so the micrcontroller will
		do the unmute when it detects audio

Darren is in NTSC-M/BTSC land.  What TV standard are you dealing with?
..

I'm in Canada, using the tuner for over-the-air NTSC broadcasts.


Try this:

	http://linuxtv.org/hg/~awalls/cx18-audio2

this waits 1.5 seconds after an input/channel change to see if the audio
standard micrcontroller can detect the standard.  If it can't, the
driver tells it to try a fallback detection.  Right now, only the NTSC-M
fallback detection is set to force a mode (i.e. BTSC), all the others
"fall back" to their same auto-detection.

Some annoyances with the fallback to a forced audio standard, mode, and
format:

1. Static gets unmuted on stations with no signal. :(

2. I can't seem to force mode "MONO2 (LANGUAGE B)".  I'm guessing the
microcontroller keeps setting it back down to "MONO1 (LANGUAGE A/Mono L
+R channel for BTSC, EIAJ, A2)"  Feel free to experiment with the LSB of
the fallback setting magic number (0x1101) in
cx18-av-core.c:input_change().


Regards,
Andy

So far, it seems fine, no black screens, and audio seems to be fine.
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