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Subject: 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.
Mike

Date: Wed, 3 Sep 2014 00:30:43 +0800
Subject: Re: how to merge fixed point wma decoder to libav 0.7.6
From: soho123.2012_at_gmail.com
To: rockbox-dev_at_cool.haxx.se

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,
so,
I do not got the point how to remove the wrapper that you add for rockboxcould you give some guide?

From: giac2000_at_hotmail.com
To: rockbox-dev_at_cool.haxx.se
Subject: RE: how to merge fixed point wma decoder to libav 0.7.6

Mike

Date: Tue, 2 Sep 2014 17:32:00 +0800
Subject: how to merge fixed point wma decoder to libav 0.7.6
From: soho123.2012_at_gmail.com
To: rockbox-dev_at_cool.haxx.se

Hi All,
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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