Expanded AudioPlayHead functionality

[ulrik]

@dustbro ok, I understand.

[d.healey]

@dustbro

Engine.getPlayHead() returns an object, any idea what properties the object has?

[Dan Korneff]

@d-healey the scripting API says:

Allows access to the data of the host (playing status, timeline, etc...). */

The JUCE Audio Processor says:

    /** Returns the current AudioPlayHead object that should be used to find
        out the state and position of the playhead.

        You can ONLY call this from your processBlock() method! Calling it at other
        times will produce undefined behaviour, as the host may not have any context
        in which a time would make sense, and some hosts will almost certainly have
        multithreading issues if it's not called on the audio thread.

        The AudioPlayHead object that is returned can be used to get the details about
        the time of the start of the block currently being processed. But do not
        store this pointer or use it outside of the current audio callback, because
        the host may delete or re-use it.

        If the host can't or won't provide any time info, this will return nullptr.
    */
    AudioPlayHead* getPlayHead() const noexcept                 { return playHead; }

I think it's currently being used to get the sample position for processing audio. There's a whole subclass to the Audio Play Head that we don't have access to yet. It would allow us to:

//==============================================================================
/**
    A subclass of AudioPlayHead can supply information about the position and
    status of a moving play head during audio playback.

    One of these can be supplied to an AudioProcessor object so that it can find
    out about the position of the audio that it is rendering.

    @see AudioProcessor::setPlayHead, AudioProcessor::getPlayHead

    @tags{Audio}
*/
class JUCE_API  AudioPlayHead
{
protected:
    //==============================================================================
    AudioPlayHead() = default;

public:
    virtual ~AudioPlayHead() = default;

    //==============================================================================
    /** Frame rate types. */
    enum FrameRateType
    {
        fps23976        = 0,
        fps24           = 1,
        fps25           = 2,
        fps2997         = 3,
        fps30           = 4,
        fps2997drop     = 5,
        fps30drop       = 6,
        fps60           = 7,
        fps60drop       = 8,
        fpsUnknown      = 99
    };

    //==============================================================================
    /** This structure is filled-in by the AudioPlayHead::getCurrentPosition() method.
    */
    struct JUCE_API  CurrentPositionInfo
    {
        /** The tempo in BPM */
        double bpm;

        /** Time signature numerator, e.g. the 3 of a 3/4 time sig */
        int timeSigNumerator;
        /** Time signature denominator, e.g. the 4 of a 3/4 time sig */
        int timeSigDenominator;

        /** The current play position, in samples from the start of the timeline. */
        int64 timeInSamples;
        /** The current play position, in seconds from the start of the timeline. */
        double timeInSeconds;

        /** For timecode, the position of the start of the timeline, in seconds from 00:00:00:00. */
        double editOriginTime;

        /** The current play position, in units of quarter-notes. */
        double ppqPosition;

        /** The position of the start of the last bar, in units of quarter-notes.

            This is the time from the start of the timeline to the start of the current
            bar, in ppq units.

            Note - this value may be unavailable on some hosts, e.g. Pro-Tools. If
            it's not available, the value will be 0.
        */
        double ppqPositionOfLastBarStart;

        /** The video frame rate, if applicable. */
        FrameRateType frameRate;

        /** True if the transport is currently playing. */
        bool isPlaying;

        /** True if the transport is currently recording.

            (When isRecording is true, then isPlaying will also be true).
        */
        bool isRecording;

        /** The current cycle start position in units of quarter-notes.
            Note that not all hosts or plugin formats may provide this value.
            @see isLooping
        */
        double ppqLoopStart;

        /** The current cycle end position in units of quarter-notes.
            Note that not all hosts or plugin formats may provide this value.
            @see isLooping
        */
        double ppqLoopEnd;

        /** True if the transport is currently looping. */
        bool isLooping;

[Dan Korneff]

@d-healey The subclass is currently commented out in HISE source code, and when i remove the comment, it doesn't compile

[lalalandsynth]

@dustbro Has this been implemented , kind of essential.

[Christoph Hart]

@lalalandsynth

HISE | Scripting | TransportHandler

A class that manages callbacks for host playback events

(docs.hise.audio)

[lalalandsynth]

@christoph-hart great !
Maybe I am overlooking something but what I am looking for is timeline sync as in :

(Slow lfo starts playing at the correct phase position according to where you are in a "measure /beat" )

OR
(Drummachine w/sequencer would start at the right place in the sequence according to timeline position)

Would "setOnBeatChange" do that ?

[Dan Korneff]

@lalalandsynth I haven't played with it since my last post on this thread. Let me know what you find.

[d.healey]

@Christoph-Hart Is it possible to find out exactly where the playhead is on the DAW timeline at a given moment? Regardless of the transport is started/stopped?

Edit: onBeatChanged seems to be the one

[Simon]

@d-healey OnBeatChanged gives you the position in beats, Engine.getPlayHead().ppqPosition I think is the most accurate and probably the one you want (and works regardless of transport state)