feat: Add input support for EBU Teletext in MPEG-TS (shaka-project#1344)

Replaces shaka-project#1181

* Add support for EBU Teletext input following Level 1.5 of the core
specification ETSI EN 300 706 V1.2.1 (2003-04).
* Add support for webvtt in MP4 segments output.

Closes shaka-project#272

---------

Co-authored-by: Marcus Spangenberg <marcus.spangenberg@eyevinn.se>

docs/source/tutorials/text.rst

@@ -45,3 +45,9 @@ Examples
       in=in_en.vtt,stream=text,language=en,output=out_en.mp4 \
       in=in_sp.vtt,stream=text,language=sp,output=out_sp.mp4 \
       in=in_fr.vtt,stream=text,language=fr,output=out_fr.mp4
+
+* Get a single 3-digit page from DVB-teletext and set language for output formats stpp (TTML in mp4), wvtt (WebVTT in mp4) and HLS WebVTT::
+
+    $ packager in=input.ts,stream=text,cc_index=888,lang=en,format=ttml+mp4,output=output.mp4
+    $ packager in=input.ts,stream=text,cc_index=888,lang=en,output=output.mp4
+    $ packager in=input.ts,stream=text,cc_index=888,segment_template=text/$Number$.vtt,playlist_name=text/main.m3u8,hls_group_id=text,hls_name=ENGLISH

packager/media/formats/mp2t/CMakeLists.txt

@@ -22,6 +22,9 @@ add_library(mp2t STATIC
   es_parser_h265.h
   es_parser_h26x.cc
   es_parser_h26x.h
+  es_parser_teletext.cc
+  es_parser_teletext.h
+  es_parser_teletext_tables.h
   es_parser.h
   mp2t_media_parser.cc
   mp2t_media_parser.h
@@ -69,6 +72,7 @@ ac3_header_unittest.cc
 adts_header_unittest.cc
 es_parser_h264_unittest.cc
 es_parser_h26x_unittest.cc
+es_parser_teletext_unittest.cc
 mp2t_media_parser_unittest.cc
 mpeg1_header_unittest.cc
 pes_packet_generator_unittest.cc

packager/media/formats/mp2t/es_parser.h

@@ -7,6 +7,7 @@
 
 #include <cstdint>
 #include <functional>
+#include <memory>
 
 namespace shaka {
 namespace media {