From: Timo Rothenpieler <timo@rothenpieler.org>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH 06/11] avutil/half2float: adjust conversion of NaN
Date: Wed, 10 Aug 2022 23:36:14 +0200
Message-ID: <423b2beb-9ad6-003e-be31-e3237f9f9788@rothenpieler.org> (raw)
In-Reply-To: <DB6PR0101MB22142AB9AF86AC250AAB91958F659@DB6PR0101MB2214.eurprd01.prod.exchangelabs.com>
On 10.08.2022 23:24, Andreas Rheinhardt wrote:
> Timo Rothenpieler:
>> IEEE-754 differentiates two different kind of NaNs.
>> Quiet and Signaling ones. They are differentiated by the MSB of the
>> mantissa.
>>
>> For whatever reason, actual hardware conversion of half to single always
>> sets the signaling bit to 1 if the mantissa is != 0, and to 0 if it's 0.
>> So our code has to follow suite or fate-testing hardware float16 will be
>> impossible.
>
> What does the exr spec say about quiet and signaling nans?
Not sure how exr would be involved here.
But I tested this on both aarch64, x86 with sse2 emulation and x86 f16c
on alderlake and zen2.
They all perfectly agree and match 100% what this changed code produces
for the entire range of 65k possible values.
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next prev parent reply other threads:[~2022-08-10 21:36 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-10 20:47 [FFmpeg-devel] [PATCH 01/11] lavu/pixfmt: add packed RGBA float16 format Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 02/11] avutil/hwcontext_d3d11va: add support for rgbaf16 pixel format Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 03/11] avfilter/vsrc_ddagrab: add rgbaf16 output support Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 04/11] avfilter/vsrc_ddagrab: add options for more control over output format fallback Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 05/11] avutil: move half-precision float helper to avutil Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 06/11] avutil/half2float: adjust conversion of NaN Timo Rothenpieler
2022-08-10 21:24 ` Andreas Rheinhardt
2022-08-10 21:36 ` Timo Rothenpieler [this message]
2022-08-10 21:43 ` Andreas Rheinhardt
2022-08-10 21:53 ` Timo Rothenpieler
2022-08-10 22:14 ` Mark Reid
2022-08-10 22:18 ` James Almer
2022-08-10 22:28 ` Timo Rothenpieler
2022-08-10 22:37 ` Mark Reid
2022-08-10 22:55 ` Timo Rothenpieler
2022-08-11 2:18 ` Mark Reid
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 07/11] avutil/half2float: move tables to header-internal structs Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 08/11] avutil/half2float: move non-inline init code out of header Timo Rothenpieler
2022-08-11 20:46 ` Michael Niedermayer
2022-08-11 20:50 ` Andreas Rheinhardt
2022-08-11 21:16 ` Michael Niedermayer
2022-08-11 21:31 ` Andreas Rheinhardt
2022-08-14 19:32 ` Michael Niedermayer
2022-08-15 4:20 ` Andreas Rheinhardt
2022-08-15 18:09 ` Michael Niedermayer
2022-08-14 21:54 ` Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 09/11] avutil/half2float: use native _Float16 if available Timo Rothenpieler
2022-08-10 21:03 ` Andreas Rheinhardt
2022-08-10 21:58 ` Timo Rothenpieler
2022-08-10 22:02 ` James Almer
2022-08-10 22:51 ` [FFmpeg-devel] [PATCH v2 " Timo Rothenpieler
2022-08-11 0:14 ` James Almer
2022-08-11 11:50 ` Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 10/11] swscale: add SwsContext parameter to input functions Timo Rothenpieler
2022-08-10 20:52 ` Timo Rothenpieler
2022-08-10 21:55 ` Andreas Rheinhardt
2022-08-10 22:02 ` Timo Rothenpieler
2022-08-10 20:47 ` [FFmpeg-devel] [PATCH 11/11] swscale/input: add rgbaf16 input support Timo Rothenpieler
2022-08-10 21:37 ` Timo Rothenpieler
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