TV Tuner (Pic. but no sound)

ntamp · 12-16-2004, 04:14 AM

Hi all,
I run Linux Slackware 10 (2.6.9 kernel) and i have a Pinnacle tv tuner (Saa 7134 chipset)
I run xawtv

Code:

xawtv -c /dev/video0

i watch "tv", but i can` t listen to any sound.
What` s the problem?
My sound card is Creative Audigy.
TIA

P.S. When i press

Code:

xawtv

i can` t watch "tv" neither listen to any sound.

theYinYeti · 12-16-2004, 07:38 AM

I had that problem: TV picture OK, but no sound (actually 2 seconds of sound and then noise). The problem disapeared by going back to kernel 2.6.7.

Yves.

ntamp · 12-19-2004, 09:31 AM

I went back to 2.6.7, but the problem still exists!
I think the problem would be solved if i tried:

Code:

xawtv -c /dev/video0 -C where/the/soundcard/installed/is

Can somebody tell me, where is the path to the sound card?
TIA

theYinYeti · 12-21-2004, 03:23 PM

Sorry for you. If you feel adventurous, you may try something like this (translation from a mail I got):

Quote:

In fact, by configuring the saa7134 module with option "audio_debug=1", I could see where the problem came from. It's a bug in the detection of the audio carrier frequency, and TV standard. Indeed, there's a short time where sound works (2s), and the module is then on SECAM-L (stereo nicam), then it switches to SECAM-B/G (mono).
So I recompiled the saa7134 module (from the sources of kernel 2.6.9), after having changed the saa7134_tvaudio.c file, so that SECAM-L and SECAM-B/G are identical.

Yves.

drj000 · 12-21-2004, 08:43 PM

Quote:

Originally posted by ntamp
i watch "tv", but i can` t listen to any sound.
What` s the problem?

Did you make sure to plug the audio out on your TV Tuner into your Audio in on your sound card? When I first got my TV Tuner I didn't realize I needed to do that, and it took about half an hour before I realized it.

aspirant_nono · 01-05-2005, 11:37 PM

Hi there, my question is to yves who seems to have everything working fine now.
How do you go about compiling your kernel module and what is there to change in the tvaudio.c file. If I did find the file, I went through it but being as fluent in C as in mandarin chinese, I don't even know what to look for. And then, even if I did, how do I compile this module?
Thanks in advance, as I've been pulling out my hair about this one for some time, I have exactly the same problem as Yves had, and with different distribs or kernel (2.6.8 or 2.6.9) the problem persists.....sound cuts off ater 2" or so.

theYinYeti · 01-06-2005, 03:52 AM

Sorry to disapoint you

I also though that my problem had disapeared. But in fact, it is still there for me, for 3 channels (others are now OK with kernel 2.6.7).
So eventually, I'll have to try what the mail I received is suggesting. But I did not try yet, so I can't help you...

I *suppose* the file must be /usr/src/linux/drivers/.../media/saa7134/saa7134_tvaudio.c, and I suppose there are some structures defined in there, one for each sound standard, and the SECAM-L has to be overwritten on the SECAM-B/G one...
Good luck. I'll report if I try.

Yves.

aspirant_nono · 01-06-2005, 11:40 AM

Thanks for your reply Yves. I did manage to find that darned tvaudio.c but C language is quite alien to me, I only recently came to Linux and the only language I know and understand is -yes i'm going to say it- VB. I'll keep looking anyways and try to understand C a bit more.

aspirant_nono · 01-07-2005, 08:06 PM

Ok Yves, I found something that works neat for me. The audio demodulator chip of the PCTV Stereo is the tda9887 and the driver (tda9887.c) is written with options port1=1 port2=1 and qss=0.
I went over to the Philips website and read all the documentation on the chip (http://www.semiconductors.philips.co.../TDA9887_3.pdf), especially pages 17, 18, 20, went through the driver sources to see that port1 defines the AGC (Automatic Gain Control)function: 0 is active. port2 is the use of an external AGC and 1 is disabled. And then QSS is the method used for the IF amplitude demodulation (yes, I know, France is the only country with AM audio on Tv waves). If QSS is put to 0, then the chip uses Intercarrier method (read the advtanges of QSS over Intercarrier for AM demodulation here: http://www.semiconductors.philips.co...2_1.pdf&e=1102).

So, basically and simply put, all I did was modify my /etc/modprobe.conf and added : options tda9887 port1=0 port2=1 qss=1 et voilà!!!! All my channels work fine now excepted France3 which I receive badly and so the sound cuts off. But for the others, everything is fine. So I guess if your Tv signal is strong, this method should work for you......unless you already tried that of course

theYinYeti · 01-10-2005, 02:18 AM

Great! And thanks for the report! I'll have to try that. Strange thing is, I remember I tried modinfo tda9887, and this gave only two parm: debug, and another generic one I don't remember; there was no port1|2, nor qss... Is modinfo reliable?

Yves.

aspirant_nono · 01-10-2005, 03:45 AM

Well, apparently not, I also tried adding a few options (look them up in the philips doc) to the tda9887.c file and recompiling such as soundtrap, PLL gating, Audio Gain +0dB but it didn't improve anything else so just setting the port1, port2 and QSS should be enough. Let me know though if the settings don't work for you, then I could always post my very own modified tda9887.c for those other options.