[FFmpeg-devel] Parallelizing MPEG encoding with MPI

[Roman Shaposhnik]

On Dec 6, 2008, at 8:08 PM, M?ns Rullg?rd wrote:
> "Jason Garrett-Glaser" <darkshikari at gmail.com> writes:
>
>> On Sat, Dec 6, 2008 at 12:20 PM, Andreas Simbuerger <simi at osaft.eu>  
>> wrote:
>>> Greetings everybody!
>>>
>>> I'm currently working on a programming exercise for my diploma at  
>>> the
>>> University of Passau. We try to enhance MPEG encoding by introducing
>>> parallelism on GOP encoding with the MPI libraries.
>>
>> Isn't MPI rather unnecessary for video encoding parallelism?  It is
>> rather easy to develop a model (see
>> http://akuvian.org/src/x264/sliceless_threads.txt) which does not
>> require communication between threads except to signal the maximum
>> motion vector search range, which can be done using an atomic write  
>> to
>> a struct variable.
>
> MPI works on networks of machines with no shared memory.

Not quite true. MPI implementations are capable of utilizing
shared memory for message passing if they notice that entities
are running on the same machine. That's one way of utilizing
those crazy multicore CPUs *and* clusters at the same time -- just
write MPI and let the runtime figure out the most efficient way
of passing messages.

Thanks,
Roman.