This PR adds parsing of teletext styling, and rendering of the styling
in output TTML and WebVTT subtitle tracks.
Beyond unit tests, I've used the sample
https://drive.google.com/file/d/19ZYsoeUfH85gEilQkaAdLbPhC4CxhDEh/view?usp=sharing
which has rather advanced subtitling with two separate rows at the same
time, where one is left aligned and another is right aligned. This
necessitates two parallel cues to be rendered. It also has some colored
text.
Solve #1335.
## parse teletext styling and formatting
Extend the teletext parser to parse the teletext styling and formatting.
This includes translating rows into regions, calculating alignment
from start and stop position of the text, and extracting text and
background colors.
The colors are limited to full lines.
Both lines and regions are propagated in the TextSample structures.
This is because the number of lines may differ from different sources.
For teletext, there are 24 rows, but they are essentially always
used with double height, so the number of output lines is 12
from 0 to 11.
There are also corresponding regions are denoted "ttx_R",
where R is an integer row number. A renderer can use either
the line number or the region ID to render the text.
## ttml generation for teletext to EBU-TT-D
Add support to render teletext input in EBU-TT-D (IMSC-1) format.
This includes appropriate regions ttx_0 to ttx_11 signalled
in the TextSamples, alignment and text and background colors.
The general TTML output has been changed to always include
metadata, layout, and styling nodes, even if they are empty.
EBU-TT-D is detected by the presence of "ttx_?" regions in the
samples. If detected, extra TTML elements will be added and
the EBU-TT-D linePadding used as well.
Appropriate styles for background and text colors are generated
depending on the color and backgroundColor attributes in the
text fragments.
## adapt WebVTT output to teletext TextSample.
Teletext input generates both a region with prefix ttx_
and a floating point line number (e.g. 9.5) in the
range 0 to 11.5 (due to input 0-23 as double lines).
The output is adopted to drop such regions
and convert the line number to an integer
since the standard only used floats for percent
values but not for plain line numbers.
This work was done over ~80 individual commits in the `cmake` branch,
which are now being merged back into `main`. As a roll-up commit, it is
too big to be reviewable, but each change was reviewed individually in
context of the `cmake` branch. After this, the `cmake` branch will be
renamed `cmake-porting-history` and preserved.
---------
Co-authored-by: Geoff Jukes <geoffjukes@users.noreply.github.com>
Co-authored-by: Bartek Zdanowski <bartek.zdanowski@gmail.com>
Co-authored-by: Carlos Bentzen <cadubentzen@gmail.com>
Co-authored-by: Dennis E. Mungai <2356871+Brainiarc7@users.noreply.github.com>
Co-authored-by: Cosmin Stejerean <cstejerean@gmail.com>
Co-authored-by: Carlos Bentzen <carlos.bentzen@bitmovin.com>
Co-authored-by: Cosmin Stejerean <cstejerean@meta.com>
Co-authored-by: Cosmin Stejerean <cosmin@offbytwo.com>
This converts all time parameters to signed, finishing a cleanup that
was started in 2018 in b4256bf0. This changes the type of:
- timestamps
- PTS specifically
- timestamp offsets
- timescales
- durations
This excludes:
- MP4 box definitions
- DTS specifically
This is meant to address signed/unsigned conversion issues on arm64
that caused some test cases to fail.
Change-Id: Ic752a20cbc6e31fea6bc0894d1771833171e7cbe
This changes the default MP4 output to use TTML and adds a way to
choose which one is used. This is done with 'format=ttml+mp4' or
'format=vtt+mp4'.
This also fixes the boxes output in WebVTT in MP4.
Change-Id: Ieaa7fc44fbf4dc020a5bb70cfa3578ec10e088ce
This only supports TTML output; meaning the user can convert WebVTT
into TTML, but not the other way around. This will be useful for
DVB-sub subtitles that would be better supported within TTML.
This only adds text-based output; a follow-up will add MP4 support.
Change-Id: I0944b7df95d7765e55f203fc5e9a644f5c455dd8
Torbjörn Einarson
Joey Parrish
Joey Parrish
Jacob Trimble