[FFmpeg-devel] [PATCH 0/9] improve rounding across FFmpeg

Ganesh Ajjanagadde gajjanag at mit.edu
Wed Dec 2 01:50:29 CET 2015


On Tue, Dec 1, 2015 at 7:39 PM, Lou Logan <lou at lrcd.com> wrote:
> On Tue,  1 Dec 2015 19:27:49 -0500, Ganesh Ajjanagadde wrote:
>
>> The slowness comes from the generate code, e.g llrint compiles down to
>> a single asm instruction cvttsd2si, while floor(x + 0.5) needs to do
>> multiple things.
>
> How much slower is it?

I don't know and honestly don't care myself as it is not really the
selling point of the patch since AFAIK these are not performance
critical. The point is really moot - I merely claimed that it is
slower, which is obvious from the asm. The more serious reasons for
avoiding it are also given in the message.

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