Chapter 6. Questions and Answers

6.1. What do I need to compile Kwave?
6.2. Which sound cards does Kwave support?
6.3. Why does Kwave consume more memory than it can be expected from the size of the opened file?
6.4. Which sound formats does Kwave support?
6.5. What if I have files with a format not supported by Kwave?
6.6. I get errors when I want to do playback?
6.7. The playback seems to do something but I hear nothing?
6.8. Some files are played with half-speed?
6.9. The playback sometimes is disturbed and interrupted?
6.10. The playback does not stop if I immediately press the stop button?
6.11. Is ALSA supported?
6.12. What about playback with 18, 20, 24 or 32 bits per sample or more than two channels?
6.13. What about MP3 support?

6.1.

What do I need to compile Kwave?

Read in the chapter mentioned before.

6.2.

Which sound cards does Kwave support?

Kwave does not need support for any special sound card. The sound card only has to be supported by your operating system and Kwave uses it's interface to the operating system's sound driver through a OSS or ALSA interface. So Kwave can play on any sound card that KDE is able to play on.

6.3.

Why does Kwave consume more memory than it can be expected from the size of the opened file?

The reason for this is that Kwave internally stores all samples in 32-bit integers. This was easy to program, made the application faster and a bit more reliable. So if you load an 8-bit file with about one megabyte it will consume about four megabytes. Maybe we will change this somewhere in the future...

6.4.

Which sound formats does Kwave support?

Kwave currently supports .wav files with 8, 16 and 24 bits per sample, with any number of channels (of course including mono and stereo). Additionally it can import all file types that libaudiofile supports and some other formats like Ogg/Vorbis and MP3.

6.5.

What if I have files with a format not supported by Kwave?

If you have to work on a different format, you can convert it into .wav format. A good set of tools for this is in the SoX package, they have also some nice documentation!

6.6.

I get errors when I want to do playback?

Maybe you have chosen a combination of playback rate and sample size that is not supported by your sound driver and / or sound hardware. Try playback with 8 bits per sample and mono first, this should always work. Then try to increase the bits per sample and stereo playback step by step. Note that some playback rates are not at all supported by some sound hardware.

6.7.

The playback seems to do something but I hear nothing?

Maybe you have forgotten to increase the volume of the playback channel. Kwave is not responsible for changing the playback volume.

6.8.

Some files are played with half-speed?

Try choosing a different sound playback device.

6.9.

The playback sometimes is disturbed and interrupted?

You should increase the size of the playback buffer to get a "smoother" playback (this also makes the playback control reacting a bit slower).

6.10.

The playback does not stop if I immediately press the stop button?

The reason for this is that the sound driver already has received some playback data from Kwave at the moment when you press the stop button. Decrease the size of the playback buffer and it should react faster (but makes interruptions more probable).

6.11.

Is ALSA supported?

Yes, since v0.7.4 for playback and recording

6.12.

What about playback with 18, 20, 24 or 32 bits per sample or more than two channels?

This is possible through the ALSA interface, since v0.7.4.

6.13.

What about MP3 support?

Well, as long as there are patent issues, we support only MP3 import through the mad library and export via the external program lame. Additionally you need to have the permission to use code covered by the MP3 patents when generating a Kwave package for distributing!