Encoding and decoding audio

At a glance

Project structure

Source bundle/
├── ACEncodeDecodeAudio/
│   ├── main.cpp
│   └── Common/
│       ├── AudioConverter.cpp
│       ├── AudioFile.cpp
│       └── AudioToolboxError.cpp
├── Common/
│   ├── AudioConverter.cpp
│   ├── AudioFile.cpp
│   └── AudioToolboxError.cpp
├── ACEncodeDecodeAudio.xcodeproj/
│   ├── .xcodesamplecode.plist
│   └── project.pbxproj
└── Configuration/
    └── SampleCode.xcconfig

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C++.
• The verified tree contains 3 project/configuration file(s) and 1 source declaration(s).

Overall architecture

flowchart LR
    N1["main"]
    N2["AudioToolbox APIs"]
    N1 --> N2

Reference code

ACEncodeDecodeAudio/main.cpp:81 — architecture anchor

int main(int argc, const char* argv[])
{
    if (argc < 4) {
        usage(argv[0]);
        return EXIT_FAILURE;
    }
    // ...
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into Audio Toolbox.

Ownership and state

classDiagram
    main --> AudioToolboxAPIs : uses

Ownership evidence

ACEncodeDecodeAudio/Common/AudioConverter.cpp:13 — stored dependency or nearest verified ownership anchor

AudioConverter::~AudioConverter() { Dispose(); }

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

No source-visible execution, scheduling, or synchronization boundary was found in the indexed source.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

ACEncodeDecodeAudio/main.cpp:18 — representative type boundary

class InputContext {
    // ...
    InputContext(AudioFile inputFile, AudioStreamBasicDescription inputDescription,
        UInt32 maxInputPacketSize, bool inputUsesPacketDescriptions)
    // ...
};

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

Common/AudioConverter.cpp:13 — representative boundary

AudioConverter::~AudioConverter() { Dispose(); }

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Naming conventions

• Types: feature-specific names rather than reusable layer suffixes.
• Protocols: no local protocol declaration in the scanned source.
• Methods: no representative method name extracted from the architectural files.
• Files: feature/project roles rather than a strict one-type-per-file rule.

Architecture takeaways

• main is the main source-visible entry or composition anchor for this sample.
• Framework work reaches sstream, AudioToolbox, iostream, vector through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation