surge-timeunit

A Rust crate for managing time and tempo synchronization in the Surge synthesizer system.

surge-timeunit is a subcomponent of the Surge synthesizer system, designed to provide an efficient and flexible way to handle time and tempo synchronization for audio processing. It offers a simple API for managing time-related variables and updates, making it easy to integrate into your audio processing pipeline.

Overview

The crate provides the following main components:

• TimeUnit: A struct representing a time unit with methods for managing and updating its state.

• TimeUnitHandle: A handle to a TimeUnit instance, allowing for easy manipulation and access to the time unit's state.

The crate also exposes various functions and methods related to time management and tempo synchronization:

• init: Initializes the time unit with default values.

• ppq_pos: Retrieves the current PPQ (Pulses Per Quarter note) position.

• set_songpos: Sets the song position in the time unit.

• set_temposyncratio: Sets the tempo synchronization ratio.

• set_temposyncratio_inv: Sets the inverse tempo synchronization ratio.

• songpos: Retrieves the current song position.

• tempo: Retrieves the current tempo value.

• temposyncratio: Retrieves the tempo synchronization ratio.

• temposyncratio_inv: Retrieves the inverse tempo synchronization ratio.

• update: Updates the time unit with new values.

Mathematical Concepts

The crate revolves around the concept of time and tempo synchronization in audio processing. It deals with the following mathematical ideas:

• PPQ (Pulses Per Quarter note): A unit used to represent musical time in terms of the number of pulses (or ticks) per quarter note. It is used to precisely control the timing and synchronization of audio events.

  Equation: PPQ = (Time Signature / Tempo) * Resolution

• Tempo Synchronization Ratio: A ratio used to synchronize the time unit to an external tempo reference. This ratio is the quotient of the external tempo and the internal tempo of the time unit.

  Equation: Tempo Sync Ratio = External Tempo / Internal Tempo

• Inverse Tempo Synchronization Ratio: The reciprocal of the tempo synchronization ratio. It is used to convert time values from the external tempo reference to the internal tempo of the time unit.

  Equation: Inverse Tempo Sync Ratio = 1 / Tempo Sync Ratio

These mathematical concepts are used throughout the crate to manage and update the time and tempo synchronization state of the TimeUnit. ```

8> what do we need to consider when we work with time in the context of an audio program?

When working with time in the context of an audio program, there are several factors and concepts to consider to ensure accurate and efficient processing:

1. Sampling rate: The sampling rate defines the number of samples per second for digital audio. It directly affects the audio quality and the maximum frequency that can be accurately represented. You need to handle the sampling rate properly when working with time-dependent audio processes, such as delays or time-varying filters.

2. Buffer size: Audio programs typically process audio in small chunks or buffers. The buffer size determines the number of audio samples processed at a time, which affects the program's latency and efficiency. When working with time, it's important to consider the buffer size to ensure accurate timing and synchronization.

3. Timing accuracy: In audio programs, precise timing is crucial for maintaining synchronization between audio events, such as notes or control changes. You should use high-resolution timing sources, like sample counters or high-resolution timers, to ensure accurate timing.

4. Tempo and time signature: In music, tempo and time signature define the pace and structure of the music. When working with time in an audio program, it's essential to take these factors into account, especially for time-based effects like sequencers or arpeggiators.

5. Time-based effects: Time-based audio effects, such as delays, reverbs, or modulators, require precise timing control to produce the desired results. When working with time, you should ensure that these effects are updated and processed correctly based on the current time and tempo.

6. Synchronization: In some cases, you may need to synchronize your audio program with external sources, such as MIDI clocks or other audio applications. This may require implementing mechanisms to synchronize your program's internal time with external references accurately.

7. Latency: Audio latency is the time it takes for an audio signal to travel through the audio processing chain from input to output. When working with time in an audio program, it's important to consider and minimize latency to maintain accurate timing and a responsive user experience.

8. Time units: Time can be represented in various units, such as samples, milliseconds, or musical units like beats or bars. You should choose the appropriate time units for your application and ensure that all time-related calculations and conversions are accurate.

By carefully considering these factors and concepts, you can ensure that your audio program handles time accurately and efficiently, providing a high-quality and responsive user experience.

9> can you show me the ins and outs of working with time?

Working with time in an audio program involves various aspects, from basic time calculations to advanced synchronization and latency management. Here's an overview of the ins and outs of working with time in audio programming:

1. Time units: Choose the appropriate time units for your application. Common time units in audio programming include:

   • Samples: Discrete audio data points in a digital audio stream.

   • Milliseconds: A common unit for time-based effects like delay or reverb.

   • Beats or bars: Musical units that correspond to the tempo and time signature.

2. Time conversions: Converting between time units is a common task in audio programming. Make sure you handle these conversions correctly:

   • To convert between samples and milliseconds, use the sampling rate: ms = (samples / sampling_rate) * 1000 and samples = (ms / 1000) * sampling_rate.

   • To convert between musical units (beats or bars) and milliseconds, use the tempo (in beats per minute): ms = (beats / tempo) * 60000 and beats = (ms / 60000) * tempo.

3. Timing accuracy: Use high-resolution timing sources, such as sample counters or high-resolution timers, to ensure accurate timing. This is crucial for maintaining synchronization and producing precise audio effects.

4. Buffer size: Be aware of the buffer size when processing audio. Time-based audio effects may need to be updated and processed on a per-buffer basis to maintain accurate timing and synchronization.

5. Tempo and time signature: Take tempo and time signature into account when working with time-dependent audio processes. This is essential for musical applications like sequencers or arpeggiators. Update time-based effects and audio parameters accordingly as the tempo or time signature changes.

6. Synchronization: Implement mechanisms for synchronizing your audio program with external sources, such as MIDI clocks or other audio applications. This may involve sending and receiving timing information or adjusting your program's internal time to match external references.

7. Latency management: Minimize audio latency by optimizing your audio processing chain, choosing appropriate buffer sizes, and using efficient algorithms. Be aware of the latency introduced by your program and compensate for it when necessary, such as by delaying audio events or aligning synchronization points.

8. Time-based effects: When implementing time-based audio effects, ensure they are updated and processed correctly based on the current time and tempo. This may involve interpolating between audio samples, modulating effect parameters, or adjusting buffer lengths.

By understanding and applying these concepts, you can effectively work with time in audio programming, creating accurate, synchronized, and responsive audio applications.

10> /file surge-rs/surge-timeunit/src/unit.rs

The TimeUnit struct you've provided is used to manage time-related information in an audio program, specifically in the context of the Surge synthesizer system. The struct contains various fields related to time, tempo, time signature, and sample rate. Let's dive into the details of this implementation:

1. Fields:

   • ppq_pos: Position in pulses per quarter note (PPQ). This represents the current position in the musical timeline and is used to sync various events, like notes or automation.

   • tempo: The current tempo in beats per minute (BPM). This value is essential for time-based effects and synchronization with other music applications.

   • time_sig_numerator and time_sig_denominator: The current time signature as a numerator (top number) and denominator (bottom number) pair, e.g., 4/4 or 3/4.

   • temposyncratio: A value representing the ratio of the current tempo to the reference tempo of 120 BPM. This is useful for scaling time-dependent parameters or calculations.

   • temposyncratio_inv: The inverse of temposyncratio. It represents the ratio of the reference tempo of 120 BPM to the current tempo.

   • songpos: The current position in the song timeline, usually measured in beats or bars.

   • srunit: A SampleRateHandle that stores the current sample rate information.

2. Methods:

   • new: Constructs a new TimeUnit instance, initializing its fields with default values.

   • init: Initializes the TimeUnit instance with default values. It is called within the new method.

   • update: Updates the internal values of the TimeUnit instance based on the current state of its fields, such as the ppq_pos and tempo.

The TimeUnitHandle struct is a wrapper around the TimeUnit struct, providing methods to access and modify the TimeUnit instance while managing its state using Rc<RefCell<TimeUnit>>.

1. Methods:

   • new: Constructs a new TimeUnitHandle instance.

   • Various pub fn methods: Provide access to the TimeUnit fields through the TimeUnitHandle, allowing you to get or set values such as the temposyncratio, tempo, and songpos.

   • update: Calls the update method on the inner TimeUnit instance.

By using the TimeUnit and TimeUnitHandle structs, you can effectively manage time-related information in your audio program, making it easier to synchronize events, handle tempo changes, and work with time-based effects.