[FFmpeg-devel] [PATCH][RFC] avcodec: disallow hwaccel with frame threads

[Andreas Cadhalpun]

On 19.01.2016 21:22, Hendrik Leppkes wrote:
> On Tue, Jan 19, 2016 at 9:13 PM, Andreas Cadhalpun
> <andreas.cadhalpun at googlemail.com> wrote:
>> On 22.10.2015 11:44, Hendrik Leppkes wrote:
>>> On Thu, Oct 22, 2015 at 11:27 AM, Wang Bin <wbsecg1 at gmail.com> wrote:
>>>> VLC is using frame threading with hwaccel
>>>
>>> Then they should fix their usage, its broken by design, as explained
>>> in detail my post earlier in this thread.
>>
>> Care to provide a patch for them?
> 
> 
> This requires deep understanding of the code in question, so nothing
> anyone not familiar with the code can easily fix, so no patches for
> downstreams will be provided.

That suggests that fixing it properly requires a lot of time.

>> They now made VLC's configure error out when compiling with FFmpeg [1],
>> because they currently lack time [2] to fix this the way you suggest
>> and Libav doesn't return this error.
>>
> 
> They don't lack time, they lack understanding of the flaws in the system.

How can you know that?

>> Thus I think it would be better to reduce this to a warning for the
>> time being and maybe add a FF_API_* changing it to an error after
>> the usual deprecation period.
>>
> 
> I do not agree that it should be a warning. As outlined in the commit
> message and this thread, there are serious flaws with frame threading
> and hwaccel.

I'm fine with it being an error, but since it is an API change, it
should follow the usual deprecation period to allow downstream users
time to fix it. Meanwhile it can be a warning so that people notice
the problem.

Best regards,
Andreas