[FFmpeg-devel] SWSCALE: Colorspace conversion for images

[Frank Barchard]

On Wed, Mar 30, 2011 at 3:27 AM, Michael Niedermayer <michaelni at gmx.at>wrote:

> On Tue, Mar 29, 2011 at 11:56:17PM -0700, Frank Barchard wrote:
> > On Tue, Mar 29, 2011 at 2:40 PM, Michael Niedermayer <michaelni at gmx.at
> >wrote:
> >
> > > On Tue, Mar 29, 2011 at 01:58:57PM -0700, Frank Barchard wrote:
> > > > Bump swscaler width limitation from 5120 to 16384.
> > > >
> > > > Advantage: images (ie jpeg) are often larger than 5120 these days.
> > > >  5120x2880 is about 15 megapixels
> > > >
> > > > Disadvantage: slightly slower
> > > >
> > > > no scaling
> > > > timex ffmpeg -y -i tulip2.mp4 tulip2.yuv
> > > > timex 8866.21ms
> > > >
> > > > scaling
> > > > C:\ffwork>timex ffmpeg -y -i tulip2.mp4 -s 1272x724 tulip2.yuv
> > > > timex 23633.13ms with VOFW 5120
> > > > timex 26246.90ms with VOFW 16384
> > >
> > > uhm
> > > could you try 21504 instead of 16384 ?
> > >
> >
> > 21504 works better.  Heres a benchmark
> >
> > VOFW 5120  VOFW 21504    Note10438.8    10344.2       timex ffmpeg -y
> > -i tulip2.mp4 tulip2.yuv25611.9    24256.9       timex ffmpeg -y -i
> > tulip2.mp4 -s 1272x724 tulip2.yuv24485.7    26006.6       "28573.1
> > 24291.3       "24069.1    26995.9       "25684.95   25387.675
> > average
>
> something is wrong with your mail client, this table is really messed
> up badly whitespace wise,maybe you used html mail and mailman removes
> html, but maybe it was something else i didnt really try to investigate
>
> heres it reformated back to readable:
> VOFW 5120  VOFW 21504    Note
> 10438.8 10344.2       timex ffmpeg -y -i tulip2.mp4 tulip2.yuv
> 25611.9    24256.9       timex ffmpeg -y -i tulip2.mp4 -s 1272x724
> tulip2.yuv
> 24485.7    26006.6
> "28573.1   24291.3
> "24069.1    26995.9
> "25684.95   25387.675    average
>

Sorry.  The reason for the table (in ascii) was the numbers fluctuate and I
wanted an average.

As I work on browsers, I do test my email works in Opera, Safari, Firefox,
IE, Chrome on Windows, Mac and Linux.  Probably my failing is I use gmail
and/or Outlook.


> This is on a Nehalem i7.  Despite being a 500 frame, 720p video, the
> numbers
> > fluctuate, so I took an average of 4 runs.
> >
> > Another reason I'd like this change is youtube accepts videos with higher
> > resolutions than 5120.
> > 16384 is vp8's maximum resolution, so that should keep us amused for a
> > little longer.
> > I thought 16k would fix into L1 better, but I guess it had collisions.
> >
> > diff --git a/libswscale/swscale_internal.h
> b/libswscale/swscale_internal.h
> > index daa6731..fc684f1 100644
>
> will apply the patch in a moment locally and push later
>

Thanks!

That said, I do like the idea of a ./configure option in the future.