[FFmpeg-devel] [PATCH 1/2] Audio Video Filtering using threads & semaphores

Nicolas George nicolas.george at normalesup.org
Tue Jun 19 22:08:01 CEST 2012

Le duodi 2 messidor, an CCXX, Manjunath Siddaiah a écrit :
> I could avoid semaphores, if threads are created for every decoded frame
> and join the threads soon after filtering that decoded frame. For this
> there will be overhead for calling thread_create function for every
> decoded frame.
> Instead created threads during "transcode_init" function and join the
> threads while exiting the transcode. For this scenario, race conditions
> are avoided using semaphores.

To avoid race conditions using POSIX threads, there are POSIX mutexes and
conditions. They are an API designed along with the rest of the threading
API and widely implemented.

Semaphores are an IPC API, and thus more expensive. They also are only an
optional part of the Unix standard, and as such missing from some systems
where POSIX threads are fully implemented.


  Nicolas George
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