[FFmpeg-devel] [PATCH] pthread: Fix ff_thread_get_formatissues when called outside frame decode.

[Hendrik Leppkes]

On Mon, Mar 9, 2015 at 7:38 AM, Rainer Hochecker <fernetmenta at online.de> wrote:
> Reimar Döffinger <Reimar.Doeffinger <at> gmx.de> writes:
>
>>
>> Any reason to believe this patch causes it?
>> Because I can't see how it would.
>> Maybe it's just a bug with DXVA and multithreading in the HEVC code?
>> Can you provide some more information like a stacktrace, possibly using a
> tool like DrMemory?
>
> I don't think the patch itself is the root cause of the issue, it just
> triggers it. get_format is called 4 times, something seems to get corrupted
> in opening our hw decoder.
> Do you have an explanation why it works with thread_safe_callbacks set to 1?
>
> I am wondering if hevc misses the multithreading fix done for other codecs:
> http://ffmpeg.org/pipermail/ffmpeg-cvslog/2013-March/062620.html
>
> What do you think?
>

I build the HEVC HWAccel support, and I consider frame-threading with
hwaccel an abomination that should not be supported, so I didn't spend
any time thinking about it.

Honestly, there are several issues with MT+HWaccel in H264 as well, at
least on Intel hardware, so I can only strongly urge everyone to not
combine it. There is zero advantages, and only downsides!

- Hendrik