Support MCC Closed Caption format

[Carl Eugen Hoyos]

A HandBrake user provided an mcc subtitle file.

$ ffmpeg -i Demo.mcc
ffmpeg version N-92967-gfc6e53b Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 6.4.0 (GCC)
  configuration: --enable-gpl --enable-libxml2 --enable-gnutls --enable-gmp --enable-version3 --enable-libx264
  libavutil      56. 25.100 / 56. 25.100
  libavcodec     58. 43.101 / 58. 43.101
  libavformat    58. 25.100 / 58. 25.100
  libavdevice    58.  6.101 / 58.  6.101
  libavfilter     7. 48.100 /  7. 48.100
  libswscale      5.  4.100 /  5.  4.100
  libswresample   3.  4.100 /  3.  4.100
  libpostproc    55.  4.100 / 55.  4.100
Demo.mcc: Invalid data found when processing input

The top of the file looks like this:

File Format=MacCaption_MCC V1.0

///////////////////////////////////////////////////////////////////////////////////
// Telestream, LLC
// Ancillary Data Packet Transfer File
//
// Permission to generate this format is granted provided that
//   1. This ANC Transfer file format is used on an as-is basis and no warranty is given, and
//   2. This entire descriptive information text is included in a generated .mcc file.
//
// General file format:
//   HH:MM:SS:FF(tab)[Hexadecimal ANC data in groups of 2 characters]
//     Hexadecimal data starts with the Ancillary Data Packet DID (Data ID defined in S291M)
//       and concludes with the Check Sum following the User Data Words.
//     Each time code line must contain at most one complete ancillary data packet.
//     To transfer additional ANC Data successive lines may contain identical time code.
//     Time Code Rate=[24, 25, 30, 30DF, 50, 60, 60DF]
//
//   ANC data bytes may be represented by one ASCII character according to the following schema:
//     G  FAh 00h 00h
//     H  2 x (FAh 00h 00h)
//     I  3 x (FAh 00h 00h)
//     J  4 x (FAh 00h 00h)
//     K  5 x (FAh 00h 00h)
//     L  6 x (FAh 00h 00h)
//     M  7 x (FAh 00h 00h)
//     N  8 x (FAh 00h 00h)
//     O  9 x (FAh 00h 00h)
//     P  FBh 80h 80h
//     Q  FCh 80h 80h
//     R  FDh 80h 80h
//     S  96h 69h
//     T  61h 01h
//     U  E1h 00h 00h 00h
//     Z  00h
//
///////////////////////////////////////////////////////////////////////////////////

UUID=636ABFEB-EE4D-4DC9-A199-94127613D57B
Creation Program=CaptionMaker Version 6.5.0.6784
Creation Date=Tuesday, March 07, 2017
Creation Time=11:46:15
Time Code Rate=30DF

00:00:00:00     T59S594F7FZ0172F4QROO73F2E02020207E3FFFE1656E67C13FFF74Z01F6BB
00:00:00:01     T59S594F77Z0272F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z021CBB
00:00:00:02     T59S594F77Z0372F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z031ABB
00:00:00:03     T59S594F77Z0472F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0418BB
00:00:00:04     T59S594F77Z0572F4FC942CROO73D2E02020207E3FFFE1656E67C13FFF74Z0556BB
00:00:00:05     T59S594F77Z0672F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0614BB
00:00:00:06     T59S594F77Z0772F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0712BB
00:00:00:07     T59S594F77Z0872F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0810BB
00:00:00:08     T59S594F77Z0972F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z090EBB
00:00:00:09     T59S594F77Z0A72F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0A0CBB
00:00:00:10     T59S594F77Z0B72F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0B0ABB
00:00:00:11     T59S594F77Z0C72F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0C08BB
00:00:00:12     T59S594F77Z0D72F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0D06BB
00:00:00:13     T59S594F77Z0E72F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0E04BB
00:00:00:14     T59S594F77Z0F72F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z0F02BB
00:00:00:15     T59S594F77Z1072F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z10ZBB
00:00:00:16     T59S594F77Z1172F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z11FEBB
00:00:00:17     T59S594F77Z1272F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z12FCBB
00:00:00:18     T59S594F77Z1372F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z13FABB
00:00:00:19     T59S594F77Z1472F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z14F8BB
00:00:00:20     T59S594F77Z1572F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z15F6BB
00:00:00:21     T59S594F77Z1672F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z16F4BB
00:00:00:22     T59S594F77Z1772F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z17F2BB
00:00:00:23     T59S594F77Z1872F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z18F0BB
00:00:00:24     T59S594F77Z1972F4QROO73D2E02020207E3FFFE1656E67C13FFF74Z19EEBB
00:00:00:25     T59S594F77Z1A72F4FC9425RFF0222FE8CFFOM73D2E02020207E3FFFE1656E67C13FFF74Z1A7BBB
00:00:00:26     T59S594F77Z1B72F4FC94ADRFF482EFE9820FEZZFE011FFE1192FE01ZFE9005FEZ0DOG73D2E02020207E3FFFE1656E67C13FFF74Z1BF4BB
00:00:00:27     T59S594F77Z1C72F4FC94F4RFF862AFE9820FE41ZFE011FFE1192FE01ZOI73D2E02020207E3FFFE1656E67C13FFF74Z1CDABB
00:00:00:28     T59S594F77Z1D72F4FC3E3ERFFC426FE9201FE083EFE3E03OK73D2E02020207E3FFFE1656E67C13FFF74Z1D55BB
00:00:00:29     T59S594F77Z1E72F4FC20C7RFF0323FE2047FE03ZOL73D2E02020207E3FFFE1656E67C13FFF74Z1E60BB
00:00:01:00     T59S594F77Z1F72F4FC4F4FRFF4323FE4F4FFE03ZOL73D2E02020207E3FFFE1656E67C13FFF74Z1F30BB

[Carl Eugen Hoyos]

​http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket7680/

[Carl Eugen Hoyos]

Fixed by Paul in 71f19bf5e31ec4039ef0f9e22b157657c57e2cb9