[MPlayer-dev-eng] Re: deinterlacing

[Tobias Diedrich]

Arpi wrote:

> > 6)
> > PAL vs. NTSC:
> > PAL has a slightly higher luma resolution, but a halfed chroma
> > resolution because of the Phase Alternating Line Color Encoding.
> > IIRC NTSC is information wise comparable to YUV422 while PAL carries
> > only as much information as an YUV411 picture...
s/YUV411/YUV420/
> hmm.
> in DV world, PAL uses Y420 while NTSC uses Y411

I think this may be to keep the data rate constant, 720*480*30 ==
720*576*25.

Some thoughts on the theoretical limits (roughly translated from a mail
I sent to video-ml at yahoogroups.de a few months ago...):

To digitize a 22khz Signal you need the double sampling frequency, that
is 44khz. With that you can digitize the complete band from 0-22khz, you
get 44100 Samples per second.

So for 640x480*29.97 samples per second I'd need a bandwith of
640*480*29.97/2Hz => 4.6Mhz.

The NTSC color carrier frequency is 3.58Mhz, which means luma bandwith
is limited to less than 3.58Mhz. The color frequency band is 3.58Mhz-x
to 3.58Mhz+x.

According to http://emcdepot.com/video_broadcast_standards.htm the
Bandwidth used for NTSC is 4.2Mhz. This results in the frequency bands
0Mhz - 2.96Mhz for luma and 2.96Mhz-4.2Mhz for chroma. Hence we could
assume the maximum luma resolution is 2.96Mhz*2/(480*29.97Hz) => 411
samples per line.

However the analog signal also carriers control information for
retrace/sync, in addition to that more lines are transfered than
displayed (525). This would yield 2.96Mhz*2/(525*29.97Hz) => 376
luma samples (Including retrace/sync).

               NTSC       PAL
FPS            29.97      25
Lines          525        625
Color carrier  3.58Mhz    4.43Mhz
Overall BW     4.2Mhz     5Mhz
Luma BW        2.96Mhz    3.86Mhz
Chroma BW      1.24Mhz    1.14Mhz
Luma Samples   376        494
Chroma Samples 157        146

This is for broadcasted analog video and composite analog video.

-- 
Tobias								PGP: 0x9AC7E0BC
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