aom on big endian systems

[Chris Cambly]

I am wondering if av1aom should work on Big Endian based systems. We were able to build the code on IBM Power based systems such as AIX but the resulting executable does not produce valid output on the system. It works correctly on IBM Linux on Power which uses Little Endian.

I see some Endian related macros in the code itself but they don't actually appear to be in any of the main line encoder code. Is there an expectation that this should work? 

[James Zern]

On Wed, Aug 24, 2022 at 3:42 PM Chris Cambly <cca...@gmail.com> wrote:

I am wondering if av1aom should work on Big Endian based systems. We were able to build the code on IBM Power based systems such as AIX but the resulting executable does not produce valid output on the system. It works correctly on IBM Linux on Power which uses Little Endian.

I see some Endian related macros in the code itself but they don't actually appear to be in any of the main line encoder code. Is there an expectation that this should work? 

Yes, it should work, but there isn't any test coverage so I wouldn't be surprised if it's broken currently. I don't think there's much powerpc code in libaom, but could you try -DAOM_TARGET_CPU=generic? You can file a bug with your findings on https://bugs.chromium.org/p/aomedia/issues/list which will make it easier to track.

[Wan-Teh Chang]

Hi Chris,

I agree with James that libaom should work on big-endian systems, but
it is likely to have bugs because we don't have access to big-endian
machines.

Could you try other open-source AV1 decoders such as dav1d and libgav1
and see if they work on IBM AIX systems?

Thanks,
Wan-Teh

[James Zern]

On Wed, Aug 24, 2022 at 6:15 PM 'Wan-Teh Chang' via AV1 Discussion <av1-d...@aomedia.org> wrote:

Hi Chris,

I agree with James that libaom should work on big-endian systems, but
it is likely to have bugs because we don't have access to big-endian
machines.

We cover other libraries like webp with qemu, it just wasn't a priority here. libwebp is known to work on big endian configurations; mips is run regularly, power was tested in the past when there were a few endian issues.

 

Could you try other open-source AV1 decoders such as dav1d and libgav1
and see if they work on IBM AIX systems?

Thanks,
Wan-Teh

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[Chris Cambly]

Thanks, I will try out the suggestions and report back.