MPEG-4 Part 17, or MPEG-4 Timed Text (MP4TT), or MPEG-4 Streaming text format is the text-based subtitle format for MPEG-4, published as ISO/IEC 14496-17 in 2006. It was developed in response to the need for a generic method for coding of text as one of the multimedia components within audiovisual presentations.

It is also streamable, which was one of the main aspects when creating the format. It is mainly aimed for use in the .mp4 container, but can also be used in the .3gp container as 3GPP Timed Text (TTXT), which is technically almost identical with .mp4 but more used in cell phones. 3GPP Timed Text is exactly the same as MPEG-4 Timed Text when used in the .mp4 container. It can be also used in other file formats based on the ISO base media file format.

3GPP approved the Timed text format for 3G multimedia services in 3GPP TS 26.245 in 2004. MPEG-4 Part 17 (ISO/IEC 14496-17:2006) defined Text Streams that are capable of carrying 3GPP Timed Text.

On October 30, 2005, Gabest added decoding support for MPEG-4 Timed Text subtitles in MPC.

See also

  • Ogg Writ
  • SubRip
  • WebVTT

References

  • GPAC MP4Box explanation of 3GPP Timed Text
  • Official MPEG web site
  • ISO/IEC 14496-17:2006 - Coding of audio-visual objects -- Part 17: Streaming text format