[FFmpeg-devel] [PATCH] AAC: type puns for 16 bit floating point rounding

Måns Rullgård mans
Mon Feb 23 02:08:20 CET 2009

Robert Swain <robert.swain at gmail.com> writes:

> 2009/2/23 M?ns Rullg?rd <mans at mansr.com>:
>> Alex Converse <alex.converse at gmail.com> writes:
>>> On Mon, Feb 16, 2009 at 7:22 PM, Alex Converse <alex.converse at gmail.com> wrote:
>>>> On Thu, Feb 12, 2009 at 9:29 AM, Robert Swain <robert.swain at gmail.com> wrote:
>>>>> 2008/12/21 Robert Swain <robert.swain at gmail.com>:
>>>>>> 2008/12/13 Guillaume POIRIER <poirierg at gmail.com>:
>>>>>>> On Sat, Dec 13, 2008 at 3:54 PM, M?ns Rullg?rd <mans at mansr.com> wrote:
>>>>>>>> Can you upload the file somewhere?  I'd rather not install mp4box just
>>>>>>>> for this.
>>>>>>> Sure, here it is: http://natsuki.mplayerhq.hu/~ml-admin/type_puns.mp4
>>>>>> M?ns?
>>>>> This thread seems to be mostly dead. Maybe Alex can do something to
>>>>> make the speed testing that needs to be done easier so we can get
>>>>> these optimisations merged into trunk, if indeed they do make decoding
>>>>> faster.
>>>> /MPlayer/incoming/aac-main/aac-main-long.adts,txt
>>>> My system reports (Linux/amd64):
>>>> before:
>>>> real    0m7.602s
>>>> user    0m7.568s
>>>> sys     0m0.032s
>>>> after:
>>>> real    0m1.182s
>>>> user    0m1.148s
>>>> sys     0m0.040s
>>>> I think we are looking for someone on ARM to test
>>> Let's try this one more time:
>>> We are looking for people on exotic architectures (non-x86) to
>>> benchmark decoding a specific file on their systems before and after
>>> the attached patch.
>>> The file: /MPlayer/incoming/aac-main/aac-main-long.adts,txt
>>> Mirror: http://filer.case.edu/ajc30/pub/ffmpeg/
>> It's faster by a wide margin on my ARM Cortex-A8 and Alpha.
> Could you make available the resulting output PCM so that its
> compliance can be verified. If we're unsure of float standards
> compliance then maybe that would be worth testing. :)

Both use IEEE floating point format, and the output only has the
occasional off by one difference between platforms.

M?ns Rullg?rd
mans at mansr.com

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