[mythtv-users] IVTV Bitrate & Resolution

Ma Begaj derliebegott at gmail.com
Sat Mar 24 21:21:07 UTC 2007

I have PAL, not NTSC.


2007/3/24, Scott Alfter <mythtv at salfter.dyndns.org>:
> Ma Begaj wrote:
> > 720x480 ?
> >
> > that's not 4:3 ...   720x540 would be 4:3 ...
> You definitely don't want to use 720x540, as there are only 480 scanlines in
> NTSC video.
> Encoding resolution and aspect ratio are really somewhat unrelated concepts.
> If you're dealing with a file format (such as an MPEG-2 program stream or an
> MPEG-4 container with H.264 video) that stores info on the video's aspect
> ratio, you can encode video at whatever horizontal resolution you want.  On
> playback, it'll be scaled appropriately to restore the correct proportions.  If
> you have 4:3 video encoded at 480x480, it'll be scaled to 640x480, 1024x768, or
> whatever on playback.  16:9 video can also be encoded at 480x480 (and on DVDs,
> it's encoded at 720x480).  For playback, it could be scaled to 852x480,
> 1280x720, etc.
> Lame formats (such as DivX AVIs) don't provide for including aspect-ratio
> information in the file, so they need to be encoded in a square-pixel format
> (like 852x480) that wastes bandwidth without providing a visible quality
> improvement.  Basically, you have to scale the video before it's encoded (and
> possibly scale it again on playback).  If aspect ratio is stored with the
> video, it only needs to be scaled once, on playback.
>   _/_
>  / v \ Scott Alfter
> (IIGS( http://alfter.us/            Top-posting!
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