On Wed, 2010-04-14 at 00:32 -0400, Mark Lord wrote: > On 13/04/10 09:45 PM, Andy Walls wrote: > The syslog shows the usual "fallback" messages, > but the audio consisted of very loud static, the kind > of noise one gets when the sample bits are all reversed. When in forced audio mode, the microcontroller will unmute. What you hear is what the decoder is decoding for BTSC. And that makes your observation *very* interesting. The sample rate conversion for SIF is fixed at about 62.937 ksps. That is 4 times the NTSC line rate of 15.734 kHz. Also note, that for anything other than simple monaural L+R audio, the BTSC subcarrier pilot and subcarrier center frequencies are based on multiples of Fh = 15.734 kHz. So if you hear something that sounds like sampling being performed at the wrong rate, I think we have one of two other problems: a. The horizontal sync tracking loop in the A/V decoder is way off (unlikely if you can see video properly) or b. the SIF signal from the analog tuner is off center. > While it was failing, I tried retuning, stopping/starting > the recording, etc.. nothing mattered. It wanted a reload > of the cx18 driver to cure it. Since you have a unit with FM radio, for a simple test, when you notice the fallback happen: 1. stop your TV capture 2. perform a short FM radio capture with ivtv-radio (it doesn't have to find a station, it shouldn't matter) 3. retry your TV capture. I'm hoping that this reconfiguration of the analog tuner's IF demodulator chip will correct any problem with the SIF output from the analog tuner. Regards, Andy BTW, that's for all your testing. It's really helpful. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
