[LV2] Lost due to no documentation on writing LV2 hosts

Harry van Haaren harryhaaren at gmail.com
Sun May 6 01:39:34 PDT 2018

On Sun, May 6, 2018 at 12:55 AM, Juan Linietsky <reduzio at gmail.com> wrote:

> Hi, I don't know anything about LV2, and I only have very little time
> available out of which I would like to port a sequencer I'm working on to
> use it.

Hi Juan,

We all started as LV2-beginners at some point :) Do you have a link to the
sequencer? I'm always curious to hear about projects.

> Unfortunately, there seems to be no documentation at all on writing hosts,
> save for a reference on Lilv, which I can't make any sense of due to me
> being completely unfamiliar with the naming conventions and context. There
> are reference server implementations, but they don't really make any sense
> either to me due to complete lack of exposure to LV2, it's conventions and
> supported functions.

Although it can be hard to "flip" at first, the plugin documentation can be
helpful, as the host does the "flip side" of the actions. I'll agree that
if starting from zero can be hard, particularly if you have to flip the
APIs to host side while learning.

> I would really like to request documentation written similar to this -
> http://lv2plug.in/book/  but seen entirely from the host side. If this
> could be done, I would enormously appreciated.

Agreed that the book is a fantastic resource to learn plugin coding!

I won't speak for the quality of the code here (it was written a long time
ago, and I'd hope I've improved since... :) but there is a sample LV2 host
class here: https://github.com/harryhaaren/Lv2Host

I hadn't looked at it in years - but testing just now it still compiles and
runs the default testing plugin ArtyFX Roomy without warnings. That said, a
quick poke with valgrind shows that there are improvements possible - so
please don't copy-paste this verbatim and expect it to work right :)

> And again, please don't insist on telling me to go read a reference or
> source code. As I mentioned, that takes way more time than I currently have
> for working on this. I believe documentation should be equally good for
> both hosts and plugin, even if there are less hosts written than plugins.

I understand nobody has infinite time - but if you're really under time
pressure think about if LV2 is really the right thing to ramp-up and learn
about. When working with new / unfamiliar libraries and code we programmers
just aren't as efficient as when we're working in our comfort zone :D

> Best
> Juan

Hope the above helps! -Harry


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lv2plug.in/pipermail/devel-lv2plug.in/attachments/20180506/ad9cd624/attachment.html>

More information about the Devel mailing list