[mythtv-users] Tuner recomendation for trial system

Cymen Vig cymenvig at gmail.com
Fri Apr 11 15:13:05 UTC 2008


On Fri, Apr 11, 2008 at 3:45 AM, David Frankland
<david at dmf-software.co.uk> wrote:
> bungle wrote:
>
> > allene222 wrote:
> >
> >
> > > Where can I get some videos that represent what I would get in various
> > > ATSC transmissions, 720p, 1080i, and various bit rates?
> > >
> > >
> > >
> >
> > http://www.fusionhdtv.co.kr/ENG/Download/Demo.aspx
> > http://www.dododge.net/roku/ts-samples.html
> >
> > Quick Google results - there were others.  The hard part will probably be
> > getting a clip long enough to test with.
> >
> >
>
>  Try Elephants Dream:
>
>  http://www.elephantsdream.org/
>
>  It's around 11 minutes.

The ~ 800 MB file I downloaded from a link at www.elephantmirrors.org
is in 1920x1080 but in an MPEG4 format. For ATSC, you'd want something
in MPEG2. Someone else on the list mentioned this site:

http://www.w6rz.net/

The files under "1080p at 24.0, 40 Mbps CBR (with no zero stuffing) in a
48 Mbps Transport Stream" are actually Elephant Dreams in 1080p MPEG2.

There is a limit to the bandwidth for ATSC / OTA HDTV and this is it
according to Wikipedia:

"A terrestrial (over-the-air) transmission carries 19.39 megabits of
data per second, compared to a maximum possible bitrate of 10.08
Mbit/s allowed in the DVD standard."

So the MPEG2 sample above is much larger than anything you'll actually
see over ATSC if the numbers are correct. There are some other samples
there that would be closer to ATSC (the 12.0 and 17.6 Mbps perhaps).
Most stations have multiple channels sharing their 19.39 megabits (PBS
has 5 here while a number of others have 2).


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