LinuxMusicians

There are now some new versions of the linuxdsp plugins here:

http://www.linuxdsp.co.uk

And a range of 'virtual guitar stomp boxes' has been added - these can be used 'live' with a low latency sound card or to add effects to existing tracks, they can be bypassed by MIDI control too so they can be switched in and out of the effects chain using (for example) a MIDI foot switch.

Hi,

Are your plugins open source?

Hey linuxdsp,
thanks for the updates

A couple of comments:
- The distortion pedal takes a lot of CPU while the phaser and sustain don't (was using the i686 build at 2x64 frames, 96kHz - kernel 2.6.31-rt11 on a debian system).
- The range of the phasing speed is not that large and one cannot control the depth.

studio32 wrote:Are your plugins open source?

As mentioned in their forum, the plugins are free-as-in-beer but not GPL.

This doesn't necessarily mean the source is not available, but it doesn't seem to be.

@thorgal: Yes the distortion does take a lot of CPU, the reason for this is that it uses 4X oversampling, oversampling is necessary because the waveshaping that occurs in the plugin will generate harmonics that are outside the original Nyquist limit and therefore would create aliases that would be audible in the output. In order to perform the oversampling it is necessary to use a Finite Impulse Response (windowed sinc) filter to effectively sample rate convert the incoming signal up to 4X the sample rate before the waveshaping. Using an FIR equates to a form of convolution which is necessarily CPU intensive (think convolution reverbs). So although it might seem like the distortion is the simpler of the plugins it actually needs the most CPU.

4 times ?? wow, that's quite a lot no wonder. I guess a technology like hyperthreading is of no use at all in this case, all the DSP has to take place in one thread, or does it ?

Yes, 4X may seem like a lot, the distortion is produced using a cubic nonlinearity (approximates to the diode soft clipping transfer characteristic in analogue circuitry commonly used in traditional fuzz boxes) therefore one would normally expect 4X to be a sensible minimum although as the effect is driven harder into clipping even at 4X some aliasing can happen but it's normally so small in level as not to be noticeable.

As regards the depth and range on the phaser, it's modelled after a vintage guitar phaser (a bit like an MXR Phase90 although I'm not claiming to emulate that - that box had a single speed control and if I recall some people liked it and some people said it didn't have enough range and you couldn't control the depth - so I take the point but I think it will stay how it is for the moment - it is what it is... I might make a more fully variable version at some time in the future).

@linuxdsp, is the source available or not?

@studio32:The plugins are free to download at the moment and they do not contain any GPL'd code. The source is not available at the moment, the reasons for this are somewhat complicated but the main reason is simply that it is not ecconomically viable to do this. At the moment the site is funded from donations (of which there are hardly any - sadly - therefore the considerable expense of hosting the site and maintaining the hardware is borne almost entirely by myself). This means that the only way I can afford to make the plugins available (at all) for free is to retain some degree of control over the intellectual property contained within them. This therefore means that I cannot release the source code at the present time. If some other form of funding becomes available then this may change but until that point the best I can do is to make them free to download.

@linuxdsp, thanks for reply.
Of course you're the owner of the copyrights and license and it's great that you make plugins for the Linux platform, no question about that. But I can't see how you make more money when you release it with a protected license then with a GPL license. Imho people are more willing to donate if it's GPL, cause then the project has more value to invest in. (Or you should sell them (which is possible with GPL too, but more tricky maybe). And I don't think the plugins of Fons Adriaensen or Steve Harris are forked because it's GPL...

Other then this the GPL license has a lot of advantages. Only check the software you use yourself e.g. JACK, Ardour, Mandriva, Openbox and your website code...
I don't know your background or what you want with your plugins in a commercial sense, but maybe you can use the plugins for advertising for some studio work (mixing/mastering) you could offer... or maybe others have some suggestions.

@studio32: Thanks for the suggestions - the way it works at the moment is a bit like this:

I developed the plugins initially for my own use because I did not see anything similar for linux and I wanted to use linux for audio because I think it is a far superior platform for this than other O/S. I decided to make them available to others in the hope they would be useful and as such I wanted them to be free or donation ware (the principle being that if everyone donates what they can / want to afford then those who can't afford to donate still get access to what is I hope good quality software) - however as I said it costs me money personally to do this (especially if no-one donates).
I could sell them (but I didn't want to do this initially - see above) If I release the source code then I can't see there is a way I could sell them - or license them as part of a commercial product - since which commercial product is going to pay me for something they can download and build themselves for free?
As it is at the moment I have more options regarding licensing and I hope I can at least still allow them to be free to download under the current license which is for non-commercial use. As I said, if other opportunities present themselves then it may be possible to make them more 'open' I'm just trying to find a way to make them available that is fair to all involved at the moment and that doesn't result in too much personal expense.