[mythtv] [mythtv-commits] Ticket #2198: Transcode treats some 1080i streams as 1088 and puts a grey line at the bottom after resizing
adeffs.mythtv at gmail.com
Sat Oct 7 23:01:49 UTC 2006
On 10/7/06, Chris Pinkham <cpinkham at bc2va.org> wrote:
> * On Sat Oct 07, 2006 at 12:10:53PM -0400, Steven Adeff wrote:
> > > there are 8 blank rows of pixels at the bottom of every frame. This patch
> > > strips those off and also calculates the new height/width based on 1080
> > > instead of 1088 if the user specified autoheight or autowidth in the
> > > transcoding profile settings.
> > >
> > > Closes #2198 by applying slightly modified patch by wagspat.
> > are they actually being stripped or just "ignored"? actually removing
> > them will decrease the quality of the encode because of the 16pixel
> > blocks, its better to set them to "black" and then set the flag for
> > the player to ignore them on playback.
> They're being stripped. Why ignore them? The transcoder automatically
> resizes your desired output size to 16-pixel boundaries when encoding MPEG-4
> so it doesn't matter what input size you start with, 1088 or 1080. By
> stripping out the 8 lines of black/gray/grey/whatever at the bottom of a
> 1080 recording, we don't waste bits reencoding those lines and don't have
> to scale it out of the picture during display.
> With MPEG-4 transcoding, the end result is that your output image size is
> rounded up to the next 16-pixel boundary in both directions
> (vertical/horizontal) and we don't have a blank line at the bottom.
> The internal player is smart enough to know that 1088 is actually only
> 1080 and doesn't display this blank line during playback. This patch
> just makes the MPEG-4/rtjpeg side of the encoder just as smart.
ah, ok, so its still encoding it as 1088, it just does it
automatically, thats cool =D
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