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I-D ACTION:draft-ietf-avt-rtp-mp3-03.txt



A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Audio/Video Transport Working Group of the IETF.

	Title		: A More Loss-Tolerant RTP Payload Format for MP3 Audio
	Author(s)	: R. Finlayson
	Filename	: draft-ietf-avt-rtp-mp3-03.txt
	Pages		: 
	Date		: 07-Aug-00
	
While the RTP payload format defined in RFC 2250 is generally applicable
to all forms of MPEG audio or video, it is less suitable for MPEG 1
or 2, layer III audio (commonly known as 'MP3').  The reason for this is
that an MP3 frame is not a true 'Application Data Unit' - it contains a
back-pointer to data in earlier frames, and so cannot be decoded
independently of these earlier frames.  Because RFC 2250 defines that
packet boundaries coincide with frame boundaries, it handles packet loss
inefficiently when carrying MP3 data.  The loss of an MP3 frame will
render some data in previous (or future) frames useless, even if they
are received without loss.
In this document we define an alternative RTP payload format for MP3
audio.  This format uses a data-preserving rearrangement of the original
MPEG frames, so that packet boundaries now coincide with true MP3
'Application Data Units', which can also (optionally) be rearranged in
an interleaving pattern.  This new format is therefore more
data-efficient than RFC 2250 in the face of packet loss.

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