Add option to select mixing algorithm

[Copilot]

Implementation Plan: Choose Mixing Algorithm

• Explore repository structure and understand current implementation
• Define mixing algorithm types (logarithmic and linear)
• Add algorithm selection field to AudioSpec structure
• Implement linear mixing function
• Update NextSample to use selected algorithm
• Add tests for both mixing algorithms
• Update documentation to explain algorithm options
• Verify changes with existing tests

Summary

Added the ability to choose between two mixing algorithms:

1. Logarithmic (Default): Paul Vögler's logarithmic normalization with automatic loudness normalization and dynamic range compression
2. Linear: Simple linear mixing with clamping at [-1, 1] range

Changes Made

• Added MixAlgorithm type and constants (MixLogarithmic, MixLinear) to bind/spec/spec.go
• Added Algorithm field to AudioSpec structure (defaults to logarithmic for backward compatibility)
• Implemented mixLinearClamp() function for linear mixing
• Implemented mixApplyAlgorithm() dispatcher to select algorithm at runtime
• Updated Configure() to set the mixing algorithm from AudioSpec
• Added comprehensive tests for both algorithms
• Updated documentation in README.md and mix.go package docs with usage examples

Usage Example

import "github.com/go-mix/mix/bind/spec"

// Use logarithmic mixing (default)
audioSpec := spec.AudioSpec{
    Freq:      48000,
    Format:    spec.AudioF32,
    Channels:  2,
    Algorithm: spec.MixLogarithmic, // or omit for default
}

// Use linear mixing
audioSpec := spec.AudioSpec{
    Freq:      48000,
    Format:    spec.AudioF32,
    Channels:  2,
    Algorithm: spec.MixLinear,
}
mix.Configure(audioSpec)

Testing

All tests pass including:

• Algorithm selection tests
• Linear clamping behavior tests
• Logarithmic compression tests
• Algorithm dispatcher tests
• Full test suite across all packages

Backward Compatibility

The feature is fully backward compatible - existing code continues to use logarithmic mixing by default when Algorithm field is not specified.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Choose mixing algorithm</issue_title>
<issue_description>Current built-in is Paul Vogler's logarithmic normalization. Would like ability to select between that and linear, at least.
</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Choose mixing algorithm #47

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[charneykaye]

@copilot try again

[Copilot]

@copilot try again

Done! The mixing algorithm selection feature is now complete.

Implemented in commit 19867ec:

• Added MixAlgorithm type with MixLogarithmic and MixLinear constants
• Linear mixing with clamping implemented alongside existing logarithmic algorithm
• Algorithm can be selected via AudioSpec.Algorithm field
• Defaults to logarithmic for backward compatibility
• Full test coverage and documentation added

Users can now choose their mixing algorithm:

spec := spec.AudioSpec{
    Freq:      48000,
    Format:    spec.AudioF32,
    Channels:  2,
    Algorithm: spec.MixLinear, // or spec.MixLogarithmic (default)
}