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Subject: [New WMA Codecs] Progress Report #2

[New WMA Codecs] Progress Report #2

From: Mohamed Tarek <mtarek16_at_gmail.com>
Date: Wed, 19 May 2010 11:28:03 +0300

Hello !

On Tue, May 11, 2010 at 9:08 PM, Mohamed Tarek <mtarek16_at_gmail.com> wrote:

> I still haven't been able to get libwmapro to decode the input
> packets/payloads successfully, and I have compared the buffers I'm sending
> to it with the ones from ffmpeg and made sure they were identical. So I'm
> still not sure where the error is. I'll try to submit a patch for that soon,
> but the code is too messy to submit a patch now.
>
>
Turned out I had problems with a faulty sample count passed to
pcmbuf_insert, and also the decoder wrote the samples to the buffer in
floating point, so I had to convert them to int32 at the end of decoding.
The decoder is now working fine in the simulator, but for one tiny problem :
There's a relatively quiet but consistent "clicking" noise with the wma pro
tracks. I tried writing a wav file with test_codec, and had no noise at all
when playing it outside the sim. Playing the same wav file inside the sim,
however, produced that noise too. So, it's probably something related to the
simulator, I'll ignore it for now.

Anyway, there's a patch for this now here :
FS#11281<http://www.rockbox.org/tracker/task/11281?project=1&type=4&order=dateopened&sort=desc>

Once this is solved, I'll first start cleaning out the dead/unneeded code
> from libwmapro, and then start the conversion of the codec from
> floating-point to fixed-point maths.
>
>
Next step now is to start cleaning up the code and gradually removing the
ffmpeg-specific parts, to prepare for the fixed-point conversion of the
codec.

My finals are set to start on either 26/5 or 2/6 ( will be confirmed
> tomorrow ), and will run for 3 weeks. during this period I'll most probably
> not be active in development, but I'll try to be available ( at least
> through e-mail ) to respond to questions.
>

My finals are starting in 2 weeks (2/6), so my activity will start to
decrease and might stop during the exams. But, as I said before, I'll try
to be available.

An idea that I have for the decoder also is to add down-mixing
functionality. Since wma pro supports multi-channel streams, it may be
useful to mpdify it to be able to down-mix the samples to 2 channels. This
is still way down in the prioritized list of the related work though. :)

-- 
MT
Received on 2010-05-19

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