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: soho123.2...@gmail.com
To: rockbox-dev@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?
2014-09-03 0:26 GMT+08:00 Mike <giac2...@hotmail.com>:
The other option of course is to use our codecs directly. You can compile the
codeclib separately from Rockbox and call it directly from another program or
using the command line. We provide most of the same formats as ffmpeg but all
integer.
From: giac2...@hotmail.com
To: rockbox-dev@cool.haxx.se
Subject: RE: how to merge fixed point wma decoder to libav 0.7.6
Date: Tue, 2 Sep 2014 09:17:13 -0700
I talked to the ffmpeg people about it almost a decade ago. Since then
floating point hardware has become very common and the need for fixed point
diminished. The closest thing I can think of would be vlc for android which
uses an early version of our fixed point decoder that is still closer to ffmpeg.
Mike
Date: Tue, 2 Sep 2014 17:32:00 +0800
Subject: how to merge fixed point wma decoder to libav 0.7.6
From: soho123.2...@gmail.com
To: rockbox-dev@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.
Or is anyone have merge fixed point wma decoder to libav?
Thanks for any input!!
