[Qt-interest] High CPU Usage With QAudioOutput

[Barnes, Clifton A.]

On Wednesday, April 06, 2011 9:42 AM Gabriel M. Beddingfield wrote:

> That's correct.  In the future, Qt is spinning off 
> modules... so the QtMultimedia classes (like QAudioOutput) 
> will now be part of the QtMobility module instead of Qt

> You said that you were passing a .wav file to the 
> QAudioOutput... but I don't think this is correct.  It is 
> expecting a RAW PCM stream, and you need to set the format. 
> However, a .wav file has metadata etc.

> Also, if you don't properly set your audio format... you 
> could be getting extra resampling or sample conversions.

Maybe there is an issue then with passing the wrong kind of file.
It does seem to play correctly though.  I am using a QFile with
the .wav file passed into the constructor.  I then pass the
address of the QFile to the QAudioOutput::start method.

aplay prints the following when running 'aplay file.wav':
    Signed 16 bit Little Endian, Rate 16000 Hz, Mono

I'm using the following to set the format:

QAudioFormat format; // Class variable

format.setFrequency(16000);
format.setChannels(1);
format.setSampleSize(16);
format.setCodec("audio/pcm");
format.setByteOrder(QAudioFormat::LittleEndian);
format.setSampleType(QAudioFormat::SignedInt);

I then pass that format object to the QAudioOutput constructor.

Is there an issue with these settings?

Clif