mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-11 19:06:33 +00:00
71 lines
2.8 KiB
Text
71 lines
2.8 KiB
Text
Gst-LV2 Quickstart
|
|
|
|
Dependencies:
|
|
|
|
Lilv 0.6.6 <http://drobilla.net/software/lilv/>
|
|
|
|
|
|
Features:
|
|
|
|
The plugin wrapper support the following plugin features:
|
|
http://lv2plug.in/ns/lv2core
|
|
http://lv2plug.in/ns/ext/event
|
|
http://lv2plug.in/ns/ext/port-groups
|
|
|
|
and these host features:
|
|
http://lv2plug.in/ns/ext/log
|
|
http://lv2plug.in/ns/ext/urid
|
|
|
|
Example Pipeline:
|
|
|
|
Requires swh-lv2 <http://plugin.org.uk/releases/>
|
|
|
|
gst-launch-1.0 -v filesrc location=/usr/share/sounds/login.wav ! wavparse ! audioconvert ! plugin-org-uk-swh-plugins-djFlanger ! audioconvert ! autoaudiosink
|
|
(A longer wav will be a better example)
|
|
|
|
gst-launch-1.0 plugin-org-uk-swh-plugins-analogueOsc num-buffers=100 wave=1 ! wavenc ! filesink location="/tmp/lv2.wav"
|
|
|
|
Requires calf <http://calf.sourceforge.net/>
|
|
|
|
GST_DEBUG="*:2,lv2:5"
|
|
gst-launch-1.0 calf-sourceforge-net-plugins-Monosynth event-in="C-3" ! autoaudiosink
|
|
gst-launch-1.0 calf-sourceforge-net-plugins-Monosynth event-in="C-3" name=ms ! autoaudiosink ms. ! fakesink
|
|
gst-launch-1.0 calf-sourceforge-net-plugins-Organ event-in="C-3" name=s ! interleave name=i ! autoaudiosink s. ! i.
|
|
|
|
|
|
TODO
|
|
* make filters gap-aware
|
|
* report latency
|
|
lilv_plugin_has_latency(), lilv_plugin_get_latency_port_index()
|
|
* support more host features
|
|
GST_DEBUG="lv2:4" GST_DEBUG_FILE=/tmp/gst.log gst-inspect lv2
|
|
grep -o "needs host feature: .*$" /tmp/gst.log | sort | uniq -c | sort -n
|
|
* make source elements useful
|
|
Most source elements use Atom port where they accept midi events. Since it is
|
|
full fledged midi, we should only ever use channel-0 and instead use multiple
|
|
instances
|
|
1) We could expose those as "audio/x-midi-event" sink pads, but then those are
|
|
not sources anymore.
|
|
2) We could expose those as properties using a new type like GST_FOURCC. If we
|
|
ignore "System Exclusive" messages, all other midi messages are 1-3 bytes.
|
|
We stuff the bytes right to left. E.g: the lowest byte is the status byte
|
|
3) We could use the GstBtNote enum + the toneconversion classes
|
|
https://www.midi.org/specifications/item/table-1-summary-of-midi-message
|
|
Open questions:
|
|
- with one property, we can't handle polyphony
|
|
- we can't query lv2 plugins for their polyphony :/
|
|
|
|
If lv2 gets a polyphony extension it would be a single non-negative integer:
|
|
0: unbound, 1 monophonic, > 1 N-polyphonic
|
|
I've checked a few synths and they all have an upper limit. Still the way
|
|
voices work in trackers is not the same as they work in synths - e.g. in a
|
|
tracker one can play a note twice
|
|
|
|
Or we just play them monophonic and try to implement a polychildbin. The bin
|
|
takes a GstElement to be used as a voice. For each new voice it would create a
|
|
new instance and it uses a built-in mixer. Downside is that all properties
|
|
would be per voice.
|
|
|
|
* example sources:
|
|
http://svn.drobilla.net/lad/trunk/lilv/utils/lv2info.c
|
|
http://svn.drobilla.net/lad/trunk/jalv/src/jalv.c
|