[mythtv-users] HD MPEG2 ->SD DVD?
george_mythusers at mari1938.org
Mon Jul 14 03:26:55 UTC 2008
Ma Begaj wrote:
> 2008/7/14 George Mari <george_mythusers at mari1938.org>:
> It would be great to be able to downscale video on the fly when a user
> wants to play HD recording or an HD Apple trailer in MythVideo with
> Does downscaling video need more power than watching it? Probably
> little bit more and I mencoder or some other tool could do it. It
> could write the output in a new file, and mplayer on the
> notebook-frontend would read from it. I did not try this, but it could
> maybe be done for mplayer/mythvideo:
> 1. user runs a scripts which should start the video playing
> 2. the scripts connects over ssh to the powerful backend and starts
> downscaling the video and saving it in a new file
> 3. a few seconds later mplayer (on the frontend) starts with reading
> from the new file
> fast forward is probably not possible.
> what do you think about this idea?
The slow part is not the scaling, it's the decoding of the MPEG2 file in
a time fast enough to get each frame onto the screen, before the next
one needs to be displayed.
Lower bitrate HD recordings are easier for slower systems to display
than ones with higher bitrates, just because there is less data to
decode. Of course the trade-off is a lower quality picture, in general.
In order to scale the video, it first has to be decoded, so the
slow/hard part has to happen first before the easier part (scaling) can
On-the-fly transcoding down to a lower bitrate and/or resolution would
be nice, but not generally doable, I think. There may be something
similar going on with some of the streaming options that I believe
MythWeb has, but I'm not certain on this.
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