Since people seem to see the necessity for some more functionality
within plugins, i want
to present LACPA (Linux Audio Cluster Plugin Api), which was intended to
be the
plugin api of the linux audio cluster (which i never finished due to the
lack of time).
Its main features:
* usable for midi/audio plugins (one plugin could be a host for other
plugins as well)
* sampleaccurate timeinfo for sequencers, tempo-synched
effects/instruments, video
* fixed size audiobuffers (good for use with networks and frequency
domain effects)
* extensible while keeping binary downward compatability
* no dependencies between host's and plugin's gui (plugins guis are
supposed to run in their own process)
BTW, by adding a control type "message", the realtime message part of
LACPA could be easily
added to LADSPA without breaking existing hosts .
Ralf
#ifndef LACPA
#define LACPA
#ifdef __cplusplus
extern "C" {
#endif
/* return value for all functions */
#define LACPA_NOT_PROCESSED 0
#define LACPA_PROCESSED 1
typedef float LACPA_FRAME; /* audio type -1.0 .. +1.0 */
typedef float LACPA_CONTROL; /* control type 0.0 .. 1.0 */
/* opaque plugin type */
typedef void * LACPA_PLUGIN;
/* initialise is called by host immediately after loading the library:
PARAMETERS:
plug2host: callback for plug -> host non-realtime messages
*/
int (*initialise)(int (*plug2host)(LACPA_PLUGIN plug, int msg, void *arg, void
*ret));
/* create a new plugin instance
Note:
a plugin is initially suspended and has its editor closed
*/
LACPA_PLUGIN (*create)(void);
/* delete a plugin instance
PARAMETERS:
plug : plugin instance returne by create()
*/
int (*delete)(LACPA_PLUGIN plug);
/* callback to be used by the plugin to send a
non-realtime message to the host.
Must be supplied by the host in initialise().
PARAMETERS:
plug: plugin instance returned by create()
msgtype: non-realtime plug -> host message type
arg: pointer to message specific arguments
ret: pointer for returning values
int (*plug2host)(LACPA_PLUGIN plug, int msgtype, void *arg, void *ret);
Following plug -> host messages are currently defined:
LACPA_EDIT_OFF: arg = NULL, ret = NULL: editor window has been closed
LACPA_IO_CHANGE: arg = NULL, ret = NULL: plugin changed its inputs or outputs
In response to this the host is supposed to suspend the plugin
and
reread the i/o configuration
*/
#define LACPA_EDIT_OFF 1
#define LACPA_IO_CHANGE 2
/* non-realtime host to plugin messages
PARAMETERS:
plug: plugin instance returned by create()
msgtype: non-realtime host -> plugin message type
arg: message specific arguments
ret: returned values
*/
int (*host2plug)(LACPA_PLUGIN instance, int msgtype, void *arg, void *ret);
/* Following plug -> host messages are currently defined:
LACPA_VENDOR_SPECIFIC: used for vendor specific messages
LACPA_PROCESS_START: arg = NULL, ret = NULL: process will be called from now
LACPA_PROCESS_STOP: arg = NULL, ret = NULL: process will not be called from
now
LACPA_PLUGIN_NAME: arg = NULL, ret = char * = name of plugin
LACPA_PLUGIN_CATEGORY: arg = NULL, ret = char * = name of plugin category
LACPA_PLUGIN_VENDOR: arg = NULL, ret = char * = name of plugin vendor
LACPA_SAMPLERATE: arr = int samplerate, ret = NULL: set the samplerate
(called while suspended)
LACPA_BUFFERSIZE: arg = int buffersize, ret = NULL: set the buffersize
(called while suspended)
LACPA_NUM_PARAMETERS: arg = NULL, ret = int = number of controls
LACPA_CONTROL_VALUE: arg = struct control, ret = char * = human readable of
the value (e.g. "-20")
LACPA_CONTROL_UNIT: arg = int index, ret = char * = human readable unit of
value (e.g. "dB")
LACPA_CONTROL_NAME: arg = int index, ret = char * = name of control (e.g.
"Gain")
LACPA_NUM_INPUTS: arg = NULL, ret = int = number of inputs
LACPA_NUM_OUTPUTS: arg = NULL, ret = int = number of outputs
LACPA_INPUT_NAME: arg = int index, ret = char * = name of audio channel
(e.g. "left input")
LACPA_OUTPUT_NAME: arg = int index, ret = char * = name of audio channel
(e.g. "left output")
LACPA_TICKS_PER_BEAT: arg int tpb: set the ticks per beat (sequencer
resolution)
LACPA_SMPTE_TYPE: arg int smpte: set the SMPTE type (see below)
LACPA_LATENCY: arg = NULL, ret = int latency: get plugin latency in samples
LACPA_EDITOR_ON: arg = NULL, ret = NULL: instruct plugin to open its editor
window
LACPA_EDITOR_OFF: arg = NULL, ret = NULL: instruct plugin to close its
editor window
*/
#define LACPA_VENDOR_SPECIFIC 0
#define LACPA_PROCESS_START 1
#define LACPA_PROCESS_STOP 2
#define LACPA_PLUGIN_NAME 3
#define LACPA_PLUGIN_CATEGORY 4
#define LACPA_PLUGIN_VENDOR 5
#define LACPA_SAMPLERATE 6
#define LACPA_BUFFERSIZE 7
#define LACPA_NUM_CONTROLS 8
#define LACPA_CONTROL_NAME 9
#define LACPA_CONTROL_UNIT 10
#define LACPA_CONTROL_VALUE_STRING 11
#define LACPA_NUM_INPUTS 12
#define LACPA_NUM_OUTPUTS 13
#define LACPA_INPUT_NAME 14
#define LACPA_OUTPUT_NAME 15
#define LACPA_TICKS_PER_BEAT 16
#define LACPA_SMPTE_TYPE 17
#define LACPA_LATENCY 18
#define LACPA_EDITOR_ON 19
#define LACPA_EDITOR_OFF 20
/* SMPTE types */
#define LACPA_SMPTE_24 1
#define LACPA_SMPTE_25 2
#define LACPA_SMPTE_30 3
#define LACPA_SMPTE_29d 4
#define LACPA_SMPTE_30d 5
/* realtime processing routine
PARAMETERS:
plug: plugin instance returned by create()
inmsg: pointer to linked list of realtime messages for plugin
outmsg: pointer to pointer to linked list for realtime messages produced by
plugin
in: pointer to array of pointers to input buffers
out: pointer to array of pointers to output buffers
*/
struct lacpa_rt_msg;
typedef struct lacpa_rt_msg *LACPA_MSG;
int (*process)(LACPA_PLUGIN plug,
LACPA_MSG *inmsg, LACPA_MSG **outmsg,
LACPA_FRAME **in, LACPA_FRAME **out);
/* realtime messages to be sent to/from plugin through process():
LACPA_MIDI: 1-3 byte midi messages
LACPA_SYSEX: Midi sysex message
LACPA_CTRL: control, range 0.0 - 1.0
LACPA_BBT: Timeinfo in Beats/Bar/Ticks
LACPA_SMPTE: Timeinfo in SMPTE FRAMES
-- more to be added as needed
*/
#define LACPA_MIDI 0
#define LACPA_SYSEX 1
#define LACPA_CTRL 2
#define LACPA_BBT 3
#define LACPA_SMPTE 4
struct lacpa_midi {
int port;
char data[4];
};
struct lacpa_sysex {
int port;
char *sysex;
};
struct lacpa_ctrl {
int index;
LACPA_CONTROL value;
};
struct lacpa_tempo {
float tempo;
};
struct lacpa_bbt {
int bar;
int beat;
int tick;
};
struct lacpa_smpte {
int hour;
int minute;
int second;
int frame;
};
struct lacpa_rt_msg {
LACPA_MSG next; /* next message in list */
int type; /* type of realtime message */
int frame; /* frame number within current process buffer */
union {
struct lacpa_midi m;
struct lacpa_sysex x;
struct lacpa_ctrl p;
struct lacpa_tempo t;
struct lacpa_bbt b;
struct lacpa_smpte s;
} lacpa_msg;
};
#ifdef __cplusplus
}
#endif
#endif /* LACPA */
