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 also allows setting the language of different text streams from
the same input. Multiple streams can use the same input stream
using different cc_index values and can each use a different language.
This also will try to pull the language from the input if not
specified.
Change-Id: I7078710b509b7d77dad8cb4299a82f954af7e9e7
Now text cues are composed of nested fragments that can be individually
styled. This allows portions of the cue to be bold, etc. The
WebVTT parser doesn't parse the inputs, but the original tags are
preserved in WebVTT output. The WebVTT output will add tags if the
style elements are present in the cue object.
Change-Id: I6abba4175e376e4f753193f7d8cac63e958d3c89
Now the Cue settings are a generic object that is parsed in WebVTT.
This will allow setting the settings in different parsers without having
to use WebVTT-specifics.
Change-Id: I36689bec725bd2e515af962b7174fc5977f96fa2
This sets the groundwork for more generic text cues by having a more
generic object for the settings and the body. This also changes the
TextSample to be immutable and accepts the fields in the constructor
instead of using setters.
Change-Id: I76b09ce8e8471a49e6bf447e8c187f867728a4bf
This change introduces handlers to output WebVtt text files. There is
only one output but there is a common base to support others.
WebVttOutputHandler which handles all communication with other handlers
and WebVttSegmentedOutputHandler is responsible for listening for events
and choosing when and where to write cues and headers.
Bug: 36138902
Change-Id: I2b13a94262554398e66fee8cf024aa21041ddbab
To ensure that the style data is formatted correctly, changing the
set_style method to AppendStyle so that joining values will be
done in controlled setting.
Change-Id: Ia88e2d260b11339e6777ff018813e8aeb802a501
Added a text sample type that can be passed between media handlers.
This will allow text samples to safely be moved between media
handlers before converting to their final format.
Bug: 36138902
Change-Id: Ic4946f774a7d37c43066b9ea46596d5c5f3c05a8
Torbjörn Einarson
Joey Parrish
Jacob Trimble
Aaron Vaage
Haoming Chen