==== MPEG4_text_descriptor

Defined by MPEG in <<ISO-13818-1>>.

[source,xml]
----
<MPEG4_text_descriptor
    textFormat="uint8, required"
    ThreeGPPBaseFormat="uint8, required"
    profileLevel="uint8, required"
    durationClock="uint24, required"
    sampleDescriptionFlags="uint2, required"
    layer="uint8, required"
    text_track_width="uint16, required"
    text_track_height="uint16, required"
    scene_width="uint16, optional"
    scene_height="uint16, optional"
    horizontal_scene_offset="uint16, optional"
    vertical_scene_offset="uint16, optional">

  <Compatible_3GPPFormat value="uint8, required"/>

  <Sample_index_and_description
      sample_index="uint8, required"
      textFormat="uint8, required">
    Hexadecimal Content
  </Sample_index_and_description>

</MPEG4_text_descriptor>
----
