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List:       kde-multimedia
Subject:    Re: [PATCH] splayplayobject resampling
From:       Stefan Westerfeld <stefan () space ! twc ! de>
Date:       2001-07-11 8:56:22
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   Hi!

On Wed, Jul 11, 2001 at 01:30:59AM +0200, Stefan Westerfeld wrote:
> I've finally implemented some resampling code for the SPlayPlayObject. The
> following works now:
> 
> % kaboodle http://swr3.mp3.unbn.unit.net:80/ 
>
> [...]
>  - I hear artefacts caused during decoding, these are not resampling based,
>    because they also occur when playing a 44100 Hz mp3 locally

I just spend a little more time debugging this, and found that KIOInputStream
was causing some problems. It used (kdelibs/arts/kde/kioinputstream_impl.cpp):

    QDataStream dataStream(m_data, IO_WriteOnly | IO_Append);
    dataStream << data;

to concatenate the data sent by the KIO::Job. The problem is that the
<< operator does append

   <the len of the QByteArray as Q_UINT32><the data of the QByteArray>

to the stream, which in turn means that the decoder will get the data with
a lot of numbers in it that don't belong there. I changed this now to

    QDataStream dataStream(m_data, IO_WriteOnly | IO_Append);
    dataStream.writeRawBytes(data.data(), data.size());

which works a lot better. However, I can still observe occasional hiccups
although I now have verified that the data that SPlayPlayObject gets is now
bytewise identical with the original mp3 the server sends.

   Cu... Stefan
-- 
  -* Stefan Westerfeld, stefan@space.twc.de (PGP!), Hamburg/Germany
     KDE Developer, project infos at http://space.twc.de/~stefan/kde *-         
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