MKVToolNix 82.0 “I’m The President”

# Version 82.0 "I'm The President" 2024-01-02

## New features and enhancements

* mkvmerge: Matroska reader: the "video alpha mode" track header property will
  be copied to the output file if present. Part of the implementation of
  #3643.
* mkvmerge: Matroska reader: the "video alpha mode" track header property will
  be reported in JSON identification mode as the track property
  `alpha_mode`. Part of the implementation of #3643.
* mkvmerge: Matroska reader: the file's timestamp scaling factor will be
  reported in JSON identification mode as the container property
  `timestamp_scale`.
* mkvmerge: MPEG transport stream reader: teletext subtitles intended for
  hearing impaired people (type 0x05) are now marked as such via the
  appropriate flag in the track headers.
* mkvmerge: file identification: the JSON identification output schema version
  has been bumped to 19.
* mkvmerge: added a new hack `always_write_block_add_ids` that can be used as
  a workaround for players that don't support the handling of missing "Block
  Addition ID" sub-elements of "Block More" elements in block additions
  properly. These are used for e.g. alpha channel data in VP9 with a "Block
  Addition ID" value of 1, which is also its default value. Workaround for the
  player issues listed in #3643.
* mkvinfo: added support for the "video alpha mode" track header element. Part
  of the implementation of #3643.
* mkvpropedit, MKVToolNix GUI's header editor: added support for the "video
  alpha mode" track header property. In `mkvpropedit` it's called
  `alpha-mode`. Part of the implementation of #3643.
* MKVToolNix GUI: multiplexer: when adding files the GUI can automatically
  enable the "hearing impaired" flag for audio and subtitle tracks if the file
  name contains the word "cc" or "sdh" delimited by certain characters
  (configurable). This feature is turned on by default. Implements #3648.
* MKVToolNix GUI: multiplexer: when scanning for Blu-ray playlists the GUI
  will now ignore playlists that are likely meant for menus. Currently the GUI
  considers this to be the case when a playlist contains the same item at
  least five times. This behavior can be turned off in the
  preferences. Implements #3658.

## Bug fixes

* mkvmerge: MPEG transport stream reader: fixed a crash introduced in v81 that
  occurred when there was at least one PCM track that wasn't copied from the
  transport stream file. Fixes #3645.
* mkvmerge: when reading data from Matroska files damaged in a specific way,
  mkvmerge ended up trying to write various types of elements that aren't
  allowed to be written (so-called `EbmlDummy` elements as well as elements
  that don't have a value set) to the output file, which caused the underlying
  `libebml` library to abort. These types of broken elements are now filtered
  out.

## Build system changes

* Qt 5 is no longer supported. Qt 6 is now required for building
  MKVToolNix. This implies that the options to `configure` revolving around
  configuring Qt 5 or choosing between the two have been removed
  (e.g. `--disable-qt6`).
* Qt 6 detection: if detection fails, error messages from `qmake` can now be
  found in `config.log`. See #3649.
* Qt 6 detection: `configure` will only consider Qt 6.2.0 or newer, not 6.0.x
  or 6.1.y anymore, due to the lack of support for the multimedia module.
* Qt 6 detection: `configure` will now fail to detect Qt 6 if the 'multimedia'
  module is not found by `qmake` (e.g. due to development packages not being
  installed). See #3649.
* The bundled `fmt` library was updated to v10.1.1.