Re: [FFmpeg-devel] Hardware purchase request Apple M2

["Martin Storsjö" <martin@martin.st>]

Hi Devin, Thilo,

On Tue, 7 Feb 2023, Thilo Borgmann wrote:

> Am 07.02.23 um 21:19 schrieb Devin Heitmueller:
>> On Mon, Feb 6, 2023 at 6:24 AM Thilo Borgmann <thilo.borgmann@mail.de> 
>> wrote:
>>> Martin pointed out we don't need an M2 for FATE as the instruction sets 
>>> are equal on both machines.
>> 
>> It may be worth noting that while the M1 and M2 have the same
>> instruction set, there is no guarantee the video processing blocks are
>> identical.  At a minimum we know that the ProRes acceleration supports
>> 8K resolutions in the M2.

Ah, good point. Yeah they're probably not identical, but I would kinda 
expect them to be mostly similar.

>> I got burned by a subtle change in behavior for videotoolbox between
>> Intel and M1,

Yeah those two implementations are entirely totally different - they 
differ on essentially every single observable detail.

>> so it's possible there are comparable differences between M1 and M2.

Yes it's somewhat possible that something could differ, but TBH I don't 
expect the difference to be very big.

E.g., I've tracked bugs in Apple's HW HEVC encoder, where the same bug has 
been observable across many generations of iPhones up until the M1 (until 
the bug was fixed in the latest iOS and macOS updates last year).

>> If the tests include validating hardware acceleration then there may 
>> still be benefits in running the tests on both platforms.
>
> Thanks for throwing that in. AFAICT we still don't cover hw accells in FATE, 
> though.

Yeah we don't do that currently - but we probably should; at least some 
level of smoke testing would be extremely useful.

In any case - I'm not arguing against using the available funds for 
getting an M2, that sounds like a totally reasonable thing to do - I'm 
just saying that I don't think it gives much extra value in the context of 
a separate FATE instance.

// Martin

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