scullery 0.1.9

A utility library based on KaithemAutomation featuring a GStreamer wrapper

scullery

Python library that provides some core parts of KaithemAutomation, especially things related to media handling.

• Data persistance
• Message bus
• Thread pool worker(At one point, Python did not natively have this, may be deprecated now that it does)
• Media handling library that gives a much nicer interface to gstreamer.
• JACK connection manager(No longer tested with actual JACK, meant for pipewire)

Intro

See example.py for more details. Also see the equally simple audio and video player.

Examples

import scullery.workers
"This file demonstrates a lot of scullery's functionality in a small package"

#Most things require this thread pool to be running
scullery.workers.start()

#Including just importing this, #Todo?
import scullery.messagebus

import scullery.persist

#Start the gst pipeline
def subscriber(topic,val):

    print("Got a message")
    
#Unsubscribe happens automatically if we don't keep a ref to the function
scullery.messagebus.subscribe("/test/topic",subscriber)

#Post a message, the actual subscribers all run in the background worker pool
scullery.messagebus.postMessage("/test/topic","TestPayload")

import time

#Also supports YAML, txt, bin for the appropriate datatypes, if the YAML lib is there.
#Can use .gz or .b2z to compress. Saved atomically with tilde files and UNIX rename semantics.
#Checks if it actually needs to save before actually writing the file.
import os
#Get an abs path
fn = os.path.join(os.path.dirname(os.path.abspath(__file__)),"testFile.json")
print("Going to save data to: "+fn)
scullery.persist.save(myData,fn)
assert scullery.persist.load(fn)==myData



while(1):
    time.sleep(1)

scullery.messagebus

scullery.messagebus.subscribe(callback,topic)

Subscribe to a topic. Topics are a slash delimited heirarchy,a # at the end is a wildcard, just like MQTT.

scullery.messagebus.subscriberErrorHandlers = []

List of functions to be called whenever an error happens in a subscribed function.

Signature must be function,topic,value.

If the function has an attribute messagebusWrapperFor, the value of that property is passed instead of the function itself. Any higher level stuff that uses the message bus must set this property when wrapping functions.

scullery.units

This module deals with unit conversions.

scullery.units.convert(value,fromUnit, toUnit)

Try to convert the value, falling back to the (very slow) pint library for less common conversions not natively supported.

scullery.mqtt

Undocumented, deprecated. The functionality is better done by raw Paho.

scullery.jack

This submodule requires pyjack, and of course Jack.

Message Bus activity

/system/jack/newport

A PortInfo object with a .name, isInput, and isOutput property gets posted here whenever a new port is added to JACK.

/system/jack/delport

A PortInfo object gets posted here whenever a port is unregistered.

system/jack/started

When jack is started or restarted

sullery.jack.startManaging()

Start the worker thread and enable management functions

scullery.jack.Airwire(from,to)

Return an Airwire object. This is a declaration that you want to connect two clients or ports and keep them connected. If you try to connect a client to a single port, all outputs get mixed down. Likewise a port to a client duplicates to all inputs.

They start in the disconnected state.

scullery.jack.Airwire.connect()

Connect and stay connected. Even if a client dissapears and comes back. Deleting the Airwire will disconnect. Note that manually disconnecting may not be undone, to prevent annoyance.

scullery.jack.Airwire.disconnect()

Disconnect.

scullery.fluidsynth

This module deals with MIDI synthesis

scullery.fluidsynth.FluidSynth(self, soundfont=None,jackClientName=None)

Creates an instance of the FluidSynth soundfont synthesizer. Soundfont is an file path, or it defaults to one that sometimes ships with fluidsynth. if jackClientName is provided, outputs audio via JACK.

You don't have to worry about cleanup, that happens automatically on GC.

Using this without JACK may not work.

fs.noteOn(channel,note,velocity)

fs.noteOff(channel,note)

fs.setInstrument(channel,instrument)

Set the instrumemt. If instrument is str, we will use the closest match we can find, or raise an error.

scullery.iceflow.GStreamerPipeline

This is the base class for making GStreamer apps

addElement(elementType, name=None, connectToOutput=None,**kwargs)

Adds an element to the pipe and returns a weakref proxy. Normally, this will connect to the last added element, but you can explicitly pass a an object to connect to. If the last object is a decodebin, it will be connected when a suitable pad on that is available.

The **kwargs are used to set properties of the element.

addPILCapture(resolution, connectToOutput=None,buffer=1)

Adds a PILCapture object which acts like a video sink. It will buffer the most recent N frames, discarding as needed.

PILCapture.pull()

Return a video frame as a PIL/Pillow Image. May return None on empty buffers.

setProperty(element, property, value)

Set a prop of an element, with some added nice features like converting strings to GstCaps where needed, and checking that filesrc locations are actually valid files that exist.

onMessage(source, name, structure)

Used for subclassing. Called when a message that has a structure is seen on the bus. Source is the GST elemeny, struct is dict-like, and name is a string.

play()

If paused, start. If never started, raise an error.

start()

Start running

stop()

Permanently stop and clean up.

pause()

What it sounds like

isActive()

Return True if playing or paused

seek(t=None, rate=None)

Seek to a time, set playback rate, or both.