4b5e80d02c
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. |
||
|---|---|---|
| .github | ||
| docs | ||
| include | ||
| link-test | ||
| npm | ||
| packager | ||
| .clang-format | ||
| .dockerignore | ||
| .gitignore | ||
| .gitmodules | ||
| .release-please-config.json | ||
| .release-please-manifest.json | ||
| AUTHORS | ||
| CHANGELOG.md | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| CONTRIBUTORS | ||
| Dockerfile | ||
| LICENSE | ||
| README.md | ||
| chromium-LICENSE | ||
README.md
Shaka Packager is a tool and a media packaging SDK for DASH and HLS packaging and encryption. It can prepare and package media content for online streaming.
Shaka Packager supports:
-
Both Video-On-Demand and Live.
-
Streaming formats:
-
Key systems:
-
Encryption standards:
-
Media Containers and codecs
Codecs ISO-BMFF WebM MPEG2-TS WVM Packed Audio² H264 (AVC) I / O - I / O I - H265 (HEVC) I / O - I - - VP8 I / O I / O - - - VP9 I / O I / O - - - AV1 I / O I / O - - - AAC I / O - I / O I O MP3 O - I / O - O Dolby AC3 I / O - I / O - O Dolby EAC3 I / O - O - O MPEG-H Audio I / O - - - - Dolby AC4 I / O - - - - DTS I / O - - - - FLAC I / O - - - - Opus I / O³ I / O - - - Vorbis - I / O - - - NOTES:
- I for input and O for output.
- ²: https://tools.ietf.org/html/draft-pantos-http-live-streaming-23#section-3.4
- ³: Opus support in ISO-BMFF is experimental.
-
Subtitles
Format Input Output Text WebVTT Y Y WebVTT in MP4 #405 Y Text TTML ⁴ Y TTML in MP4 - Y DVB-SUB Y - Teletext #272 - - ⁴: TTML input is only supported with TTML output (pass-through, DASH only), see also #584.
- Platforms
- Linux
- Mac
- Windows
- Cross compiling for ARM is also supported.
1: Limited support
Getting Shaka Packager
There are several ways you can get Shaka Packager.
- Using Docker. Instructions are available here.
- Get prebuilt binaries from release.
- Built from source, see Build Instructions for details.
Useful Links
- Announcement List (join for infrequent announcements and surveys)
- Subscribe to releases by following instructions from this blog- Documentation
- Tutorials
- Several open source players:
Contributing
If you have improvements or fixes, we would love to have your contributions. See https://github.com/shaka-project/shaka-packager/blob/main/CONTRIBUTING.md for details.