[FFmpeg-devel] [PATCH] Efficiently support several output pixel formats in Cinepak decoder

wm4 nfxjfg at googlemail.com
Tue Feb 7 20:05:32 EET 2017

On Tue, 7 Feb 2017 12:54:23 -0500
"Ronald S. Bultje" <rsbultje at gmail.com> wrote:

> Hi,
> On Tue, Feb 7, 2017 at 12:04 PM, <u-9iep at aetey.se> wrote:
> > cinepak, rgb24            19.7     (via the fast bilinear swscaler)
> > cinepak, internal rgb565   6.0  
> The reason that your decoder-integrated colorspace convertor is so much
> faster than swscale is because swscale is converting internally to yuv420p
> using a scaling filter, and then back to rgb565 using another scaling
> filter. This is "easily" solved by adding a direct (possibly
> x86-simd-accelerated) rgb24-to-rgb565 converter into
> libswscale/swscale_unscaled.c, which would likely have nearly identical
> performance to what you're seeing here. Possibly even faster, because
> you're allowing for simd optimizations.

I'm also wondering how much performance the 3 byte rgb24 format costs
as opposed to using a 4 byte padded format like rgb0.

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