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QuickTime-style chapter tracks are the native chapter format for Apple's ecosystem. They use a disabled text track (hdlr type "text") referenced by a chap track-reference in the audio track's tref box. This format is recognized by QuickTime, iTunes/Music, Final Cut Pro, Logic Pro, DaVinci Resolve, VLC, and most other MP4/M4A players. It is also the format that AVFoundation reads natively via AVAssetChapterMetadataGroup. The implementation produces output that matches ffmpeg's chapter track structure byte-for-byte: per-sample stts entries (required by AVFoundation), encd atoms for UTF-8 text encoding, edts/elst edit lists, gmhd with gmin+text media information, and disabled tkhd flags (track_in_movie only). Key behaviors: - write() inserts tref + chapter trak as a single contiguous block, then appends text samples in an mdat atom at EOF - Handles non-zero first chapter times by prepending a dummy chapter at time 0 (stripped on read) - Overwrite support: removes existing chapter track before writing - Preserves existing metadata tags and audio data integrity - Uses timescale=1000 (milliseconds) for chapter track timing 7 new tests covering write/read round-trip, remove, overwrite, tag preservation, empty file read, timestamp precision, and non-zero first chapter handling.
TagLib
TagLib Audio Metadata Library
TagLib is a library for reading and editing the metadata of several popular audio formats. Currently, it supports various metadata containers such as ID3v1, ID3v2 and Vorbis comments for MP3, MP4, AAC, Ogg, Opus, FLAC, Speex, APE, MPC, WavPack, WAV, AIFF, TrueAudio, Matroska, WebM, ASF, WMA, DSF, DFF and tracker (MOD, XM, S3M, IT) files.
TagLib is distributed under the GNU Lesser General Public License (LGPL) and Mozilla Public License (MPL). Essentially that means that it may be used in proprietary applications, but if changes are made to TagLib they must be contributed back to the project. Please review the licenses if you are considering using TagLib in your project.