[FFmpeg-devel] [PATCH] libavcodec/qsvenc_hevc: correction for QSV HEVC default plugin selection on Windows

[Mark Thompson]

On 06/12/2018 05:21, Li, Zhong wrote:
>> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
>> Of Landgraph
>> Sent: Thursday, December 6, 2018 4:23 AM
>> To: ffmpeg-devel at ffmpeg.org
>> Subject: Re: [FFmpeg-devel] [PATCH] libavcodec/qsvenc_hevc: correction for
>> QSV HEVC default plugin selection on Windows
>>
>> Hi All,
>>
>> This is my first commit to ffmpeg, what should I do to merge it?
>>
>> Do we have any reasons to not merge this?
>>
>> Thanks!
> 
> Will apply if nobody against now. 

Please add a note to the commit message explaining the original problem so that if anyone does come across it they can understand what's going on.  Old drivers do hang around for a long time, especially with the OEM-locked ones.

Ok with that change.

Thanks,

- Mark


>> 23.10.2018 10:14, Li, Zhong пишет:
>>>> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On
>> Behalf
>>>> Of Maxym Dmytrychenko
>>>> Sent: Sunday, October 14, 2018 3:36 AM
>>>> To: ffmpeg-devel at ffmpeg.org
>>>> Subject: Re: [FFmpeg-devel] [PATCH] libavcodec/qsvenc_hevc:
>>>> correction for QSV HEVC default plugin selection on Windows
>>>>
>>>> On Sat, Oct 13, 2018 at 6:43 PM Mark Thompson <sw at jkqxz.net> wrote:
>>>>
>>>>> On 06/10/18 07:21, Landgraph wrote:
>>>>>> 1. Old logic meaned: everywhere, except Windows, ffmpeg has to use
>>>>>> HW
>>>>> acceleration, but on Windows ffmpeg has to use (unavailable)
>>>>> software encode by default
>>>>>> 2. Software encode is available only if you provide corresponding
>>>>> software MediaSDK library, which isn't provided with ffmpeg. More
>>>>> information could be found in
>>>>>
>>>>
>> https://github.com/Intel-Media-SDK/MediaSDK/blob/master/doc/samples/r
>>>> e
>>>>> adme-encode_linux.pdf
>>>>>> 3. HW encode is available on Windows in the driver by default
>>>>> This has been proposed before - I can't find the original discussion
>>>>> (maybe it was on IRC), but I did find <
>>>>>
>>>>
>> https://lists.libav.org/pipermail/libav-devel/2016-November/080419.html>.
>>>>> The reason for not doing it is that a subset of the Intel drivers
>>>>> segfault immediately when the hardware plugin is loaded on some
>>>>> platforms.  That's a pain for anyone wanting to support diverse
>>>>> systems, so the decision was to continue to load the sw plugin by
>>>>> default so it doesn't crash (even if the software plugin isn't
>>>>> present), and leave the non-default case as the crashing one so the
>>>>> user
>>>> has to do something to trigger it.
>>>>> If you can characterise either the set of platforms it crashes on or
>>>>> a set of platforms it definitely works on then maybe we could
>>>>> conditionally change the default behaviour?
>>>>>
>>>>> - Mark
>>>>>
>>>>>
>>>> it was 2 years old discussion and with early drivers (we even had
>>>> this development a bit ahead of general driver availability) now it
>>>> should be working on most of the platforms - I would suggest to make a
>> positive side.
>>> Basically, HEVC HW encoding should be the default case if HW platform
>> can support.
>>> If crashed with some specified drivers, thus should be a driver issue instead
>> of hiding it in ffmpeg level.
>>> So, I agree with Maxym and the patch LGTM.
>>> (Of course, if we can verified on the platforms which was crashed as
>>> two years ago, that should be fine. However, IMHO this is not MUST. If
>>> it is still crash, reporting a bug to the driver developer should be
>>> the right way.)
>>>