Tap-to-time provides the user the ability to tap to the lyrics/syllables
of the song in order to time lines or karaoke. It consists of these
extra UI interactions:
- **Indicator**: tap marker: a designated marker that can be moved to
the current audio position; indicated in:
- the audio display by a green arrow underneath a marker
- the karaoke display by a green-colored syllable
- **Control**: tap marker: the tap marker can be changed by selecting
syllables on audio display in karaoke mode, or clicking the markers on
audio display in dialogue mode
- **Control**: ctrl-right-click audio display: starts playing the audio
from that exact position until the end of the file
- **Option**: Timing/Tap To Time: enables the tap marker indicator and
commands
- **Button**: time_opt_tap_to_time: toggles the Timing/Tap To Time option
- **Button**: time_tap_connect (hotkey I): a command that:
- moves the tap marker's position to the current playing audio
position
- sets the next marker to be the tap marker
- if the tap marker is already the last marker AND BOTH autocommit AND
next-line-on-commit is ON, will move onto the next line
- if moved on to the next line, also sets the start marker to the current
audio position, so the two lines are connected, and moves to the
next tap marker (essentially reinvoking time_tap_connect once)
- **Button**: time_tap_no_connect (hotkey O): similar to
time_tap_connect, except it will not set the next line's start
position even if moved to the next line
Expected workflow:
1) User loads song lyrics
2) User splits each line into syllables
3) User turns on tap-to-time, autocommit, and next-line-on-commit
4) User plays audio from beginning, tapping time_tap_connect to each
syllable, occasionally tapping time_tap_no_connect when a break between
lines is desired
5) If user messes up a line, they can set the tap marker to where they
want to restart from, and ctrl-right-click to start the audio a few
seconds before it
6) Syllables can be split/merged at will, and adjustments to timing can
be done using normal karaoke timing controls
Having the timing correction in MoveMarker is extremely surprising
behavior if any other part of the code uses MoveMarker expecting it to
work correctly as advertised
Some matroska files have audio start at timestamp 0 and video later.
In this case mkvtoolnix seems to use the first block of the first
cluster to the audio track (I would assume this is only an
implementation detail and not really from the matroska specs. And also
could happen in other cases without the video being delayed, but that's
not the point). Aegisub used to read this first block and use its
timestamp as the starting point of the video track.
With this commit, Aegisub tries to read all the blocks until it can read
the first timestamp of the video track and use it for the subtitles'
timestamps. Audio tracks don't seem to be impacted by these changes.
odrling