[MPEG4_text_descriptor.ThreeGPPBaseFormat]
Bits = 8
0x10 = Timed Text as specified in 3GPP TS 26.245

[MPEG4_text_descriptor.profileLevel]
Bits = 8
0x10 = Base profile, base level

[MPEG4_text_descriptor.sampleDescriptionFlags]
Bits = 2
1 = Out-of-band only
2 = In-band only
3 = Both in-band and out-of-band

[MPEG4_text_descriptor.textFormat]
Bits = 8
1         = Timed Text as specified in 3GPP TS 26.245
0xF0-0xFE = User-private
