[FFmpeg-devel] [PATCH] Yield on AVERROR(EAGAIN).

[Luca Abeni]

Michael Niedermayer wrote:
> On Fri, Mar 05, 2010 at 11:46:03AM +0100, Luca Abeni wrote:
>> Michael Niedermayer wrote:
>>> On Fri, Mar 05, 2010 at 08:23:07AM +0100, Reimar D?ffinger wrote:
>>>> On Fri, Mar 05, 2010 at 03:48:52AM +0100, Michael Niedermayer wrote:
>>>>> What you suggest needs a select() like system that works with files,
>>>>> network protocols, audio and video grab APIs as well as screen capture
>>>>> APIs needs to work on all platforms
>>>>> that support yield()/sleep() of some kind and needs to work with
>>>>> any set of supported protocols on that platform and needs protocols
>>>>> to pass thier file/object handle(s) through demuxers to the user app so
>>>>> it can do that select() call
>>>> Actually... No, it would be enough for the devices to just do a select 
>>>> themselves.
>>>> After all, our networking code does not just do a non-blocking read and 
>>>> then
>>>> just returns EAGAIN if it didn't get anything.
>>> this should be fixed of course
>> The networking code does not support the AVFMT_FLAG_NONBLOCK flag.
>> I tried adding support for it in the UDP and RTP protocols some
>> time ago (this is actually quite trivial), but then I had issues with
>> some other code in libavformat (av_find_stream_info(), if I remember
>> well - but I might be wrong) that is not prepared to it...
>> Then, I ran out of time :)
> 
> av_find_stream_info() will block from the users point of view, unless the
> user stops it through url_interrupt_cb()
> 
> is there some other problem with it?

I might be wrong (maybe I remember the wrong problem :), but I seem to
remember that it consumed 100% of the CPU if the network returned EAGAIN
because of AVFMT_FLAG_NONBLOCK.
I'll have a better look, and I'll try to remember the details, during
the weekend.


				Luca