[mythtv-users] Optimal capture resolution for DVD burning

[Nick Craig-Wood]

Michael T. Dean <mtdean at thirdcontact.com> wrote:
>  On 07/26/06 12:54, JCA wrote:
> 
> >>You can change the width of the capture and still have DVD compliant
> >>MPEG, eg 352x480 is reasonable quality and low datarate.
> >>
> >>Note that the acceptable output formats for DVD are (from DVD FAQ)
> >>
> >> MPEG-2, 525/60 (NTSC): 720x480, 704x480, 352x480
> >> MPEG-2, 625/50 (PAL):  720x576, 704x576, 352x576
> >> MPEG-1, 525/60 (NTSC): 352x240
> >> MPEG-1, 625/50 (PAL):  352x288
> >
> >    What kind of quality loss can be expected when bringing the
> >capture resolution from 720x480 to 352x480? Will it be clearly
> >noticeable?

Probably not - see below

>  See this link from my post in this thread:
>  http://www.gossamer-threads.com/lists/mythtv/users/121593#121593
> 
> > Is it the case that the resulting MPEG files are going to
> >be smaller, or is this something to do with the recording maximum
> >bitrate?
> >
>  100% determined by bitrate...

That is certainly true.

The quality question is a different matter...

I did some tests on some high quality material (from DVB) I wanted to
transcode to DVD.  For lower bitrates say at about the 2-3 Mbit/s
level, I found 352x480 to give higher perceptual quality than 720x480.

Having to encode twice as many bits for the 720 wide stream in only 2
Mbit/s means that other things get lost in a noticeable fashion.

I think 352x480 probably matches quite well the info content of SDTV
broadcast.  Tweak the bit rate so you get the quality you desire at
the disk space you want.

According to this (the font of all (mis)information)

  http://en.wikipedia.org/wiki/Display_resolution

NTSC only has a horizontal resolution of about 270 lines.

Ultimately you'll have to suck it and see - it will depend on the
quality of the MPEG encoder, your TV reception etc!

-- 
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick