Rockbox mail archiveSubject: RE: how to merge fixed point wma decoder to libav 0.7.6
RE: how to merge fixed point wma decoder to libav 0.7.6
From: Mike <giac2000_at_hotmail.com>
Date: Tue, 2 Sep 2014 10:45:41 -0700
There is no wrapper around ffmpeg for rockbox, the original ffmpeg code has been rewritten to process data one frame at a time instead of one superframe at a time like ffmpeg did. This was a problem on lower speed devices because superframes could be very large, resulting in audio drop outs. Actually, a large part of the original codec has been rewritten to work better on low speed devices rather than PCs.
Do you actually need the ffmpeg interface? I would probably not try to use it here as it is not well suited to what you want to do unless your embedded device is quite fast. Instead I would take a look at wma.c, which does a very simple loop calling asf_read_packet (to read an ASF packet), then wma_decode_superframe_init to prepare a superframe for decoding, and finally a loop of wma_decode_superframe_frame that returns decoded PCM samples.
If you do need an ffmpeg interface, you could probably write a wrapper around these functions.
Date: Wed, 3 Sep 2014 00:30:43 +0800
Subject: Re: how to merge fixed point wma decoder to libav 0.7.6
but the usage of library seems different with original ffmpeg libav, for example:in rockbox, there is wma_decode_superframe_init, but in general ffmpeg libav does not include wma_decode_superframe_init,
I do not got the point how to remove the wrapper that you add for rockboxcould you give some guide?
Subject: RE: how to merge fixed point wma decoder to libav 0.7.6
Date: Tue, 2 Sep 2014 17:32:00 +0800
Subject: how to merge fixed point wma decoder to libav 0.7.6
Is there anyone have idea about how to merge fixed point wma decoder to libav 0.7.6? because my cpu does not include fpu, when use the wma decoder in libav , it take a lot of cpu time.
Thanks for any input!!
Received on 2014-09-02
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