An equality operator is added for the chapters. The chapters are
only written to the file if they were really modified, so just
reading the chapters without modifying them will not affect
the save operation.
Six new tests exercise corners of the chapter implementation that the
orphaned-mdat fix did not reach:
testQTChapterListUnicodeTitles / testChapterListUnicodeTitles --
Round-trip Japanese, German (umlaut), and Russian titles through the
QT text-sample serialisation and the Nero length-prefixed UTF-8 path
respectively. These are separate paths in the code and benefit from
separate coverage.
testQTChapterListEmptyTitleStripped --
A multi-chapter list whose first entry is empty at t=0 matches the QT
dummy-marker pattern; read() must drop it. Test documents the rule so
a regression is immediately detectable.
testQTChapterListSingleEmptyTitleNotStripped --
The stripping rule only applies when size > 1. A single empty-title
chapter at t=0 is valid and must be preserved.
testNeroAndQTChaptersAreIndependent --
Both formats can coexist; removing one leaves the other intact.
Validates the lazy saveChaptersIfModified contract in mp4file.cpp.
testNeroChaptersAloneWhenNoQT --
Writing one format must not create atoms for the other.
All 47 MP4 tests pass.
The previous fix for orphaned chapter mdats assumed the chapter text
mdat was dedicated and derived its location from stco[0] - 8. In
audiobooks that co-locate chapter text at the start of the primary
audio mdat (stco[0] == audioMdat.offset + 8), that arithmetic lands
on the audio mdat header, the "mdat" signature check passes, and the
full audio payload gets removed -- shrinking a 484 MB audiobook to
5.4 MB.
Fix: resolve the chapter mdat by finding the top-level mdat whose
data range contains stco[0], then re-parse after the trak/tref
removals and confirm no other track's stco/co64 points into that
mdat before deleting it. Shared mdats are left intact; the dead
chapter text bytes remain as harmless padding.
Add a regression test that writes a chapter track, patches its
stco[0] to point into the primary audio mdat (simulating the
audiobook layout), removes the chapter track, and verifies the
audio mdat is byte-identical afterwards.
Adds testQTChapterListNoOrphanedMdat which performs three add/remove
cycles and asserts that the top-level mdat count is identical before and
after. Without the fix, each cycle leaves an orphaned mdat at EOF, so
three cycles produce originalCount + 3 atoms.
Uses TagLib's own MP4::Atoms parser as the primary check, with
AtomicParsley as an optional cross-validation when installed.
Changes made
mp4chapterlist.h
• Added (MP4::File*) overloads for read, write, remove
• Replaced broken class File; forward declaration with #include "mp4file.h" (fixed a subtle C++ name-resolution linker bug where Atoms(File*) resolved to MP4::File* instead of TagLib::File*)
mp4chapterlist.cpp
• Refactored: path-based overloads are now thin wrappers that delegate to file-based overloads
• File-based overloads construct Atoms locally — no Atoms* in the public API
• Removed chplHeaderSize = 9 constant; replaced the minimum-size guard in parseChplData with a correct 5-byte check (the old constant was version-1 specific and would reject valid version-0 atoms)
mp4qtchapterlist.h
• Added (MP4::File*) overloads for read, write, remove
• Removed Atoms* parameters entirely from the public API
mp4qtchapterlist.cpp
• Same refactor: path-based overloads delegate; file-based overloads construct Atoms locally
• Added empty-chapter guard: write(MP4::File*, {}) delegates to remove(file) instead of writing a 0-sample chapter track
tests/test_mp4.cpp
• Added testChapterListFileAPI and testQTChapterListFileAPI — exercise the full write/read/remove cycle via the file-based API
• Updated test bodies to use the simplified (MP4::File*) API (no MP4::Atoms construction in test code)
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.
Implement read/write/remove of Nero-style chapter markers (chpl atom)
in MP4 files. The chpl atom lives at moov/udta/chpl, storing up to 255
chapter entries with 100-nanosecond timestamps and UTF-8 titles.
Includes CppUnit tests covering round-trip read/write, remove, tag
preservation, and reading from files with no chapters.
Some encoders write a valid data chunk but with a slightly too-large
declared chunkSize, or place the data chunk beyond the declared RIFF
boundary. The previous behaviour called break, abandoning all remaining
chunks and making the file appear empty to taglib.
Lenient parsers (ffmpeg, QuickTime) handle this case by clamping the
chunk size to the bytes that actually remain in the file. Adopt the
same strategy: when chunkSize would exceed the file length, clamp it
and continue parsing rather than stopping early.
Read, write, and remove Broadcast Audio Extension (BEXT, EBU Tech 3285)
and iXML metadata chunks in WAV files. BEXT is widely used in broadcast
and professional audio for originator, description, time reference, and
loudness metadata. iXML is used by field recorders and DAWs for scene,
take, and track metadata.
MPEG::File::isSupported() scans for frame sync bytes that can appear
in other files, causing them to be misidentified as MP3.
This also includes a test with such a file.
Make AttachedFile immutable. This is consistent with SimpleTag and
Chapter and avoids using attached files which do not have all required
attributes.
Provide methods to insert and remove a single simple tag, so that
they can be modified without setting all of them while still not
exposing internal lists to the API.
Use DATE_RECORDED instead of DATE_RELEASED for year() and the "DATE"
property. This is more consistent with other tag formats, e.g. for ID3v2
"TDRC" is used, which is the recording time.
The C bindings would convert a char* to String using the default
constructor, which uses the Latin1 encoding, breaking when a key
contains a Unicode character (e.g. an ID3v2 comment description).
The involvement/involvee pairs which are supported for TIPL properties
(ARRANGER, ENGINEER, PRODUCER, DJ-MIX, MIX) are left in the TIPL
frame, other pairs are moved to a TMCL frame. This will result in a
consistent behavior for both ID3v2.3 and ID3v2.4 tags produced by
MusicBrainz Picard.
The following user-settable values for CMake are supported:
- TESTS_DIR: Tests directory, is path to unit test data when 'data' is
appended. Can be used to run the unit tests on a target.
- TESTS_TMPDIR: Directory for temporary files created during unit tests,
system tmpdir is used if undefined. Has to be defined on systems
without global temporary directory.
* Add Shorten (SHN) support
* Add `<cmath>` include and use `std::log2`
* Use `uintptr_t` for buffer size calculations
* Work around `byteSwap` not using fixed width types
* Remove four-character codes
* Attempt to fix `static_assert`
* Revert previous commit
* Update `read_uint`* functions
* Use ByteVector for byte swaps
* Use different ByteVector ctor
* Rework variable-length input to use ByteVector
* Rename some variables
* Naming and formatting cleanup
* Add basic Shorten tests
* Rename a constant
* Rename `internalFileType` to `fileType`
* Add documentation on `fileType` meaning
* Add DO_NOT_DOCUMENT guard
* Fix shadowVariable issues reported by cppcheck
cppcheck --enable=all --inline-suppr \
--suppress=noExplicitConstructor --suppress=unusedFunction \
--suppress=missingIncludeSystem --project=compile_commands.json
* Formatting cleanup
* More explicit types
Reason for these changes: getRiceGolombCode(k, uInt32CodeSize) was
called with int k for uint32_t& argument.
There was also a warning from MSVC for line 299:
warning C4267: 'argument': conversion from 'size_t' to 'int'
* Additional explicit types
* Rename `SHN` namespace to `Shorten`
Also rename files to match
---------
Co-authored-by: Urs Fleisch <ufleisch@users.sourceforge.net>
