The plugins (services) are basically raw. All we really know about them
from at the binary perspective is their name and type (producer,
consumer, filter, transition). However, an application needs to be able
to gather more information. Currently, some applications are just
building the metadata into their own app, possibly through source code,
or just some form of config files. This is intended to address that.
- A schema - a standard
structure and set of field names so applications can automatically process it. In other
words, docs/services.txt is not sufficient.
- Easy for module authors. This means it might be a text file provided
with the module, which is obviously simple and easy for a static set
of services and properties. However, some services are bridges to
another modular system like ladspa or frei0r. In that case, the
module needs to be able to provide the metadata programmatically
at runtime. Again, it should be simple and convenient for this
scenario as well.
- Should be optional - an app can use a module it knows intimate
knowledge without having the framework filter it out for lack of
- Contain enough information to let the app generate a UI - both the
service browser and the service editor.
- Contain default values for parameters
- Accommodate future requirement for animation (mutable properties
with key frames and interpolation) to replace current system of
- A module may call mlt_repository_register_metadata
for each of its services.
- The module will supply a properties tree to
- The framework will take care of
free-ing the metadata properties memory so modules do not have to worry
about their lifetime.
- Add a mlt_properties_parse_yaml variant to
mlt_properties_load so modules can author its metadata in a very small
subset of YAML. I do not
want to add a XML parser to the framework. I could use the existing
mlt_properties_load, but the file format is already similar to yaml.
And I like yaml over xml and something unique. Of course, nothing
prevents a module from using its own xml parser, but I want don’t want
to add the parser requirement to a framework service (mlt_properties).
- Add YAML Tiny
(PLEASE READ) support to mlt_properties.
- Remember, modules don’t have to have a yaml file representing their metadata. It
can all be done programmatically.
- Modules can install their metadata
file(s) in $(datadir)/<module>/metadata/
- Modules can load their metadata file(s) using
- Schema version - in case the schema changes, then apps can be
programmed for flexibility
- Service implementation version
- Taxonomy of tags: Audio, Video, Luminance, Chrominance, Frequency, Wipe,
Distortion, Delay, Amplifier, Pitch, Bandpass, Spectral, Lowpass,
Highpass, Comb, Utility, Waveshaper, Generator, Equalizer, Flanger,
Compressor, Limiter, Expander, Oscillator, Measurement, Gate, Simulator,
Reverb, Filter, Chorus, Notch, Phaser, Allpass, Modulator, Dynamics,
Mixer, Motion, Interlace, Temporal, Size, Transform, Resample, Noise, Sharpness
- Dublin Core Elements v1.1: identifier, creator,
contributor, language, title, description, type
- Use ISO 639-1 codes as supported by gettext
- The glib
contains code for getting this from the environment.
- The framework
will provide this list of these locale names to the mlt_metadata
- The framework exposes a mlt_repository_metadata(
service_type, service_name ) function to query and lookup metadata. It
- The framework expects modules to include a
mlt_metadata callback if it can provide metadata. * This system
prevents modules from having to register metadata at load time reducing
- The mlt_metadata callback will supply the
service_type, service_name, and locales as a null-terminated array of
- Metadata shall be cached in the repository along with the
- Modules that provide presets must implement the
mlt_presets callback, which gets a service_type and service_name as
parameters and returns a mlt_properties.
- Presets schema TBD
- Widget taxonomoy: knob, slider, radio, checkbox, spinner, combo,
menulist, listbox, color, textbox, timecode, fileopen, filesave, curve,
color, font, rectangle (for mlt_geometry)
- If icon/filename is relative, it is relative to $(datadir)($datadir is e.g.
- The current MLT Tiny YAML implementation only
supports 2 space characters for indentation!