I also have a device that has the SAA7113 chip in it. Kworld 315U. I suggested a patch to add a an s_power function to the code but it looks like the patch didn't work. I have to do some cleanup to it and resubmit it. Franklin Meng --- On Thu, 2/4/10, Devin Heitmueller <dheitmueller@xxxxxxxxxxxxxx> wrote: > From: Devin Heitmueller <dheitmueller@xxxxxxxxxxxxxx> > Subject: Re: Any saa711x users out there? > To: "Andy Walls" <awalls@xxxxxxxxx> > Cc: "Linux Media Mailing List" <linux-media@xxxxxxxxxxxxxxx> > Date: Thursday, February 4, 2010, 8:34 PM > Hey Andy, > > On Thu, Feb 4, 2010 at 11:15 PM, Andy Walls <awalls@xxxxxxxxx> > wrote: > > Hmmm. The AGC (or static gain level?) of the > amplifier in the SAA7113 > > before the anti-alias filter may be set too high > causing the clipping > > (intermods) there. It may be worth looking at the > gain setting for that > > amp. > > It's possible. One thing I did as a test though was I > did a capture > of the i2c traffic under Windows (using the same reference > video > source), and then compared the register programming (via > some scripts > I whipped up). There were some other registers that > were different, > but the only one that made *any* visible difference in the > output was > the AA flag. > > > The visible effects of the anti-alais filter could > possibly be: > > > > 1. Less range of color, if high freqs of the color get > attenuated. > > (Most people likely will not perceive this as most > people are not that > > sensitive to small color variations.) > > > > 2. Loss of rapid variations in Luma - softer edges > between light and > > dark areas on a scan line - if higher freqs of the > Luma get attenuated. > > > > but given that the anti-alais filter is essentially > flat out to about > > 5.6 MHz and has a slow rolloff (only 3 dB down at > about 6.9 MHz), I > > doubt anyone would ever notice it is on with NTSC. > > To give you a better idea of what I'm talking about, look > at this image: > > http://imagebin.org/83458 > > The above image was taken with the generator via the > s-video input > (ruling out the possibility that it's any sort of product > of > intermodulation). > > For the sake of comparison, here's the exact same signal > source > against an a similar em28xx design but with the tvp5150. > > http://imagebin.org/83459 > > > Since you have a signal generator, you should run > experiments with PAL-D > > and SECAM-D with a grid containing vertical lines > since those both have > > a 6.0 MHz video bandwidth. SECAM also has FM color, > so you might see > > the greatest affect of an antialias filter on color on > the Cyan color > > bar in SECAM-D. > > Believe it or not, I'm actually having trouble with the > generator > right now with anything but NTSC. I'm going back and > forth with > Promax on repair options. So I cannot do any PAL or > SECAM testing > right now. > > On a separate note, I really should look at extending the > v4l2 > capture-example to a version that let's me do a direct > capture of the > YUYV frame and convert the output into a zero-loss RGB > format. It's > too easy to be mislead by things the applications are doing > like > deinterlacing, rescaling, blending, and compression of the > screenshot > when saving to a file. > > Devin > > -- > Devin J. Heitmueller - Kernel Labs > http://www.kernellabs.com > -- > 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 > -- 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
