[mythtv] Tuning remarks

[Daniel Kristjansson]

On Thu, 2005-08-18 at 14:10 +0200, Daan de Beer wrote:
> As promised I took a shot at checking the tuning code to figure out why my 
> tuning was so bad. 
>  
> I have for example the channel RTL7. This is located at 648000000 Hz. 
> Therefore I must use channel 43 which is at 647250000 Hz. 
<cut fine tune stuff>
You can specify the exact frequenty in dtv_multiplex.

BTW When using V4L2 you can never specify the frequency exactly. If the
card supports VIDEO_TUNER_LOW, you can tune within 62.5 Hz, but if it
doesn't you can only tune within 62500 Hz. This isn't a huge problem
since the hardware can find the exact frequency by syncing to the
carrier with a PLL. With V4L1 you can only tune within 62500 Hz.

The changes in fine tune were a couple months back, and had to do 
with a systematic error that crept into higher frequencies with the
old calculation. Search for the commit message for a more detailed
explanation.

-- Daniel