[FFmpeg-devel] Video codec design for very low-end decoder

[Lauri Kasanen]

On Mon, 7 Jan 2019 13:44:56 +0100
Michael Niedermayer <michael at niedermayer.cc> wrote:

> > The modern approaches, DCT, FFT, wavelets and such transforms, are all
> > likely too slow to decode.
> 
> you said it can do mpeg1 and xvid, these are DCT based
> have you tried H.264 ? (i imagine that might with asm optimizations
> and avoidance of more complex features like CABAC and the loop filter
> work maybe, maybe not)
> also if h.264 with everything disabled works maybe some features can
> be turned on sometimes like the loop filter for key frames, that 
> might then help compression ...
> 
> and beating an existing codec, while certainly possible might be hard

According to a 2010 comparison
https://keyj.emphy.de/video-encoder-comparison/
x264 constrained baseline (everything off) takes something like 30%
longer to decode vs xvid at the same rate. Probably more because that
site used xvid's full features, while I used it "everything off".

The issue with xvid simple and mpeg1 were that they were slightly too
slow, and looked too bad. The platform does not have any SIMD, so I
doubt asm optimizations will help much.

Cinepak is almost 30 years old, surely it should be possible to match
the decoding & quality, but at a 5x lower bitrate :P

- Lauri