CrescendoKit

Binary distribution of Crescendo, a comprehensive Swift audio playback engine for Apple platforms.

dependencies: [
    .package(url: "https://github.com/kushalpandya/CrescendoKit", from: "<latest available version>")
]

The product and module are named Crescendo (the package is the distribution; the engine is what you use):

.target(name: "YourApp", dependencies: [
    .product(name: "Crescendo", package: "CrescendoKit")
])

import Crescendo

Documentation

API documentation for the latest release is published at kushalpandya.github.io/CrescendoKit.

Package Artifacts

Release packages include prebuilt XCFrameworks (macOS, universal for Apple Silicon and Intel; other platforms in future):

Framework	Description	License
CFFmpeg.xcframework	FFmpeg, audio-only LGPL build, dynamically linked	LGPL 2.1+
Crescendo.xcframework	The playback engine with TagLib statically embedded	Proprietary (EULA) + MPL 1.1
Crescendo.doccarchive	Public API documentation	Proprietary (EULA)

Crescendo.xcframework is a mixed-license artifact: the proprietary engine statically incorporates TagLib (plus the thin C shim whose source lives in Shims/) under the MPL 1.1. The framework's Resources/ carry COPYING.MPL and TagLib-NOTICE.txt alongside the Crescendo EULA, and each release attaches the exact verified TagLib source archive (taglib-<version>.tar.gz) as its corresponding source.

The product lists both frameworks because Crescendo links CFFmpeg via @rpath; consumers embed the two XCFrameworks automatically.

Building Dependencies

The FFmpeg and TagLib artifacts can be built from source using the scripts included in this project.

./Scripts/build-ffmpeg.sh    # requires nasm + gpg (brew install nasm gnupg)
./Scripts/build-taglib.sh    # requires cmake (brew install cmake)

upstream.lock controls the version and authenticity of the downloaded sources: it pins each upstream release version together with its tarball's SHA-256 hash, verified before extraction. FFmpeg downloads are additionally verified against the FFmpeg release signing key present in Keys/ffmpeg-signing-key.asc.

Run either script with --check-updates to compare the pins against the latest upstream releases; the lock file's comments describe the update workflow.

License

See LICENSE.md for the full map. In short:

• This repository's source (build scripts, Shims/, manifest) is MIT.
• FFmpeg is built LGPL-only (no GPL, no non-free components; TLS via Apple SecureTransport) and consumed as a dynamic framework, keeping it replaceable per LGPL §6. The license text ships inside the framework (Resources/COPYING.LGPLv2.1), and the exact source version, configure flags, and build script live in this repository.
• TagLib is dual LGPL 2.1 / MPL 1.1; this distribution elects the MPL 1.1 and embeds TagLib statically inside Crescendo.xcframework (the MPL's file-level copyleft permits this in a proprietary Larger Work). The license text and a notice identifying the exact version and corresponding source ship inside the framework (Resources/COPYING.MPL, Resources/TagLib-NOTICE.txt); TagLib's source is used unmodified, the verified source archive is attached to every release, and the shim source plus the build pipeline that reproduce the embedded component are published in Shims/ and Scripts/build-taglib.sh.
• Crescendo is a proprietary binary, licensed under the Crescendo EULA. For uses beyond its scope, please get in touch.

Author

Kushal Pandya