[FFmpeg-devel] [PATCH v2] swscale/output: Altivec-optimize float yuv2plane1

[Carl Eugen Hoyos]

2018-12-17 8:37 GMT+01:00, Lauri Kasanen <cand at gmx.com>:
> On Mon, 17 Dec 2018 01:03:36 +0100
> Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>
>> 2018-12-16 10:06 GMT+01:00, Lauri Kasanen <cand at gmx.com>:
>> > This function wouldn't benefit from VSX instructions, so I put it
>> > under altivec.
>> >
>> > ./ffmpeg_g -f rawvideo -pix_fmt rgb24 -s hd1080 -i /dev/zero -pix_fmt
>> > grayf32le \
>> > -f null -vframes 100 -v error -nostats -
>> >
>> > 3743 UNITS in planar1,   65495 runs,     41 skips
>> >
>> > -cpuflags 0
>> >
>> > 23511 UNITS in planar1,   65530 runs,      6 skips
>> >
>> > grayf32be
>> >
>> > 4647 UNITS in planar1,   65449 runs,     87 skips
>> >
>> > -cpuflags 0
>> >
>> > 28608 UNITS in planar1,   65530 runs,      6 skips
>> >
>> > The native speedup is 6.28133, and the bswapping one 6.15623.
>>
>> > Fate passes
>>
>> I wonder a little how, given that grayf32 already breaks fate as-is...
>
> Are the tests for it disabled? fate.ffmpeg.org reports 100% success for
> many platforms.

Iirc, it is broken with --disable-sse

>> Note that this function / this pix_fmt currently has no real use-case
>> afaict.
>
> Is there a list of which pix fmts are useful? Of course I don't want to
> waste both my and reviewers' time, if the format is considered for
> removal or otherwise broken.

The pix_fmt is not deprecated (it's new), what I meant was that it is
currently only used for obscure monochrome Photoshop images
and one filter, so I am not sure optimizing this colour conversion
will help often.

But this is of course not very much related to this patch, sorry
for the noise!

Carl Eugen