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This specification defines segment formats for implementations of Media Source Extensions™ [MEDIA-SOURCE] that choose to support MPEG-2 Transport Streams [MPEG2TS].
It defines the MIME-type parameters used to signal codecs, and provides the necessary format specific definitions for initialization segments, media segments, and random access points required by the Byte Stream Formats section of the Media Source Extensions™ specification. This document also defines extra behaviors and state that only apply to this byte stream format.
The MIME-type/subtype pair of "video/MP2T", as specified in [RFC3551], MUST be used for byte streams that conform to this specification.
The following parameter can be used in the MIME-type passed to isTypeSupported
()
or addSourceBuffer
()
.
MPEG-2 TS media segments and initialization segments MUST conform to the MPEG-2 TS Adaptive Profile [MPEG2TS].
The user agent MUST run the append error algorithm if any of the following conditions are met:
An MPEG-2 TS initialization segment consists of a single PAT and a single PMT.
The user agent MUST run the append error algorithm if any of the following conditions are met:
The user agent MUST accept and ignore other SI, such as CAT, that are invariant for all subsequent media segments.
The user agent MUST source attribute values for id
, kind
, label
and language
for AudioTrack
, VideoTrack
and
TextTrack
objects as described for MPEG-2 Transport Streams in the in-band tracks spec [INBANDTRACKS].
The user agent MUST run the append error algorithm if any of the following conditions are met:
A random access point as defined in this specification corresponds to Elementary Stream Random Access Point as defined in [MPEG2TS].
Timestamp rollovers and discontinuities MUST be handled by the UA. The UA's MPEG-2 TS implementation MUST maintain an internal offset variable, MPEG2TS_timestampOffset, to keep track of the offset that needs to be applied to timestamps that have rolled over or are part of a discontinuity. MPEG2TS_timestampOffset is initially set to 0 when the SourceBuffer is created. This offset MUST be applied to the timestamps as part of the conversion process from MPEG-2 TS packets into coded frames for the coded frame processing algorithm. This results in the coded frame timestamps for a packet being computed by the following equations:
Coded Frame Presentation Timestamp = (MPEG-2 TS presentation timestamp) + MPEG2TS_timestampOffset
Coded Frame Decode Timestamp = (MPEG-2 TS decode timestamp) + MPEG2TS_timestampOffset
MPEG2TS_timestampOffset is updated in the following ways:
abort
()
is called, MPEG2TS_timestampOffset MUST be set to 0.timestampOffset
is successfully set, MPEG2TS_timestampOffset MUST be set to 0.As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.
The key words MAY, MUST, and SHOULD in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.