TransOggChangesFromOgg - Revision history

Xiphmont: minor wording

2012-09-03T16:04:03Z

minor wording

← Older revision		Revision as of 16:04, 3 September 2012
Line 5:		Line 5:
	== Full stream metadata on every packet ==		== Full stream metadata on every packet ==

	Most containers replicate some codec data into the container layer for ease of implementation, balancing overhead/complexity with convenience. This pushes back (but does not eliminate) the need for a codec-specific 'stubs' or '~~packetizers~~'.		Most containers replicate some codec data into the container layer for ease of implementation, balancing overhead/complexity with convenience. This pushes back (but does not eliminate) the need for a codec-specific 'packetizer stubs' or 'mux shims'.

	The original Ogg design took a 'maximally minimalist' stance on stream		The original Ogg design took a maximally minimalist stance on stream
	metadata, not replicating any data into the container layer that could		metadata, not replicating any data into the container layer that could
	be provided by a codec stub. This was not a popular design decision		be provided by a codec stub. This was not a popular design decision
	to put it mildly, ~~mainly~~ because it pushed more of the implementation		to put it mildly, substantially because it pushed more of the implementation
	work out of the container lib and onto external framework implementors.		work out of the container lib and onto external framework implementors.

Xiphmont at 10:34, 27 May 2010

2010-05-27T10:34:41Z

← Older revision		Revision as of 10:34, 27 May 2010
Line 33:		Line 33:
	= Metadata =		= Metadata =

	As in the original Ogg design, metadata is encapsulated within the		The core philosophy of
			building a layered container out of a basic streaming transport is
			unchanged. As in the original Ogg design, metadata is encapsulated within the
	low-level transport as a stream. Unlike the original Ogg, transOgg		low-level transport as a stream. Unlike the original Ogg, transOgg
	metadata is mandatory and necessary for stream operation. Metadata		metadata is mandatory and necessary for stream operation. Metadata

Xiphmont: Created page with 'TransOgg is intended to be the next major revision of the Ogg container. The major changes over the original container are summarized below. = Transport Changes = == Full stre…'

2010-05-27T10:33:22Z

Created page with 'TransOgg is intended to be the next major revision of the Ogg container. The major changes over the original container are summarized below. = Transport Changes = == Full stre…'

New page

TransOgg is intended to be the next major revision of the Ogg container. The major changes over the original container are summarized below.

= Transport Changes =

== Full stream metadata on every packet ==

Most containers replicate some codec data into the container layer for ease of implementation, balancing overhead/complexity with convenience. This pushes back (but does not eliminate) the need for a codec-specific 'stubs' or 'packetizers'.

The original Ogg design took a 'maximally minimalist' stance on stream
metadata, not replicating any data into the container layer that could
be provided by a codec stub. This was not a popular design decision
to put it mildly, mainly because it pushed more of the implementation
work out of the container lib and onto external framework implementors.

For that reason, transOgg goes the opposite direction. It stamps full
container metadata on every packet, pushing back the need for
packetizers even further, and hopefully saving more work.

== Generalized/formalized timing and interleave metadata ==

The timing, interleave, structure, and codec-specific fields must be
fully generalized, specified and declared by the container.

== New lacing scheme ==

Packet size encoding is tweaked to use a new extension pivot; rather
than extending the packet size encoding from an extension value of
255, the new pivot is 252. This allows the length of any packet
segment in a page to be encoded in at most three bytes, preserves
small-packet encoding efficiency and also allows signalling for runs
of zero-packets in null-packet based VFR schemes.

= Metadata =

As in the original Ogg design, metadata is encapsulated within the
low-level transport as a stream. Unlike the original Ogg, transOgg
metadata is mandatory and necessary for stream operation. Metadata
uses stream ID 0 in all links. All other stream IDs must be unique to
the complete stream.

== Structural metadata ==

This is the essential metadata required for operation of the
transOgg's mux layer. As in the original Ogg, no metadata is required
to capture, parse and recover packets from the page stream, however
structural metadata is required to interpret many of the values
contained in the page. This data exists in the form of a
header/footer pair and is mandatory.

* Per-stream metadata, such as timing, sync/order flags, codec flags, etc.
* Mandatory stream-global information (enumeration of codecs)
* Per-stream codec setup information (codec headers)
* seeking index (optional)
* Chaining linkage

== Semantic metadata ==

This is metadata used to properly present or semantically augment the
data of the stream itself.

* Stream relationships (primary/secondary angles, languages, overlays, etc)
* Non-linear features such as chapters
* Fixed (header/footer) and streamable semantic metadata
* Streamed (rolling) headers for in-band capture

= More Information =

* [[TransOgg]]: Toplevel transOgg page