Le 24 nov. 2009 à 00:42, Ratin a écrit : > Jean-Daniel Dupas <devli...@...> writes: > >> >> >> Le 21 nov. 2009 à 10:28, Ratin a écrit : >> >>> Hi All, I am developing an app that opens multiple streams and read >>> data in threads and que in buffers, using avcodec as a demuxer, the >>> code is contained in one shared object module which is dynamically >>> loaded by the app (lets call it streamer module). I am then passing >>> the same AVFormatContexts to another shared object module that I load >>> dynamically by the app (lets say decoder module), to regain the >>> AVCodecContext from the AVFormatContexts and, open the codec to decode >>> whats in the queue. >>> >>> The problem I am having has to do with having codec open in both of >>> these modules, in the comments for the prototype of avcodec_open, it >>> states that this function is not thread safe.To me that means I cant >>> have two copies of codec opened with the same codec contexts in both >>> modules. If thats true, then what would be the best way to reopen a >>> codec which relates to the same codec context that I have opened on >>> the streamer module. I could probably pass around pointer to codec >>> itself but then how to get back the format contexts and avcontexts? >>> >> >> You can register a lock manager using av_lockmgr_register(). >> This manager will be call in avcodec_open() and avcodec_close() to prevent > race condition. >> > > Thanks for your reply. > > My problem has to do with what pointers I should pass around so I can open the > right decoder. > > Is it possible to: > > 1. Open the stream with av_open_input_file and av_find_stream_info (or > av_open_input_stream) which populates the codec context values based on whats > on > the file > 2. Change the fields in returned codec context and call avcodec_find_decoder > to > open HW accelerated decoder instead of what it finds by default? > avcodec_find_decoder doesn't return HW accelared decoder by default. > >
AFAIK, you can freely change the fields as needed before opening the codec, as long as it remains consistent with the file content (at least, fieldw marked as 'set by user' in the AVCodecContext struct declaration). You can for example, set the AVCodecContext->get_format field before opening, and returns an HW accelerated format from this callback (I don't know it this is enough to use an HW codec though). -- Jean-Daniel _______________________________________________ libav-user mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/libav-user
