SLIDE 1
Background & Purpose
- ATRAC-X
– Newest member of ATRAC family of perceptual codecs – ATRAC technology widely used in MDs and solid-state recorders/players
- Adoption
RTP Payload for ATRAC-X Matthew Romaine Mitsuyuki Hatanaka (Sony - - PowerPoint PPT Presentation
RTP Payload for ATRAC-X Matthew Romaine Mitsuyuki Hatanaka (Sony - - PowerPoint PPT Presentation
RTP Payload for ATRAC-X Matthew Romaine Mitsuyuki Hatanaka (Sony Corporation) Background & Purpose ATRAC-X Newest member of ATRAC family of perceptual codecs ATRAC technology widely used in MDs and solid-state
SLIDE 2
SLIDE 3
Features of ATRAC-X
- Higher sound quality at lower bit-rates
- Wide range of bit-rates, from 8kbps to
1.4Mbps
- Support for multi-channel encoding
- Flexible format for future extensions
- Suitability for streaming, including scalability
and fixed frame lengths
SLIDE 4
Features of the ATRAC-X Payload Format
- Multiple bit-stream packetizing
- Support for metadata
- Packet loss resolution via “redundant data”
- Support for fragmentation
SLIDE 5
Some Definitions
- ATRAC-X Audio Frame
– Smallest unit of ATRAC-X data – 2048 PCM samples
- ATRAC-X Segment
– Unit of ATRAC-X data inside RTP packet – Any combination of audio, metadata, and respective redundant frames
- ATRAC-X Slot
– Unit of time within which all audio frames of an ATRAC-X segment belong.
SLIDE 6
Overview of ATRAC-X streaming
- n RTP
N+1 N+1 N+1 N+1 N N N N N+2 N+2 N+2 N+2
Time (“slot”) StreamID
1 2 3 1 2
N
= ATRAC-X Segment with sequence N
SLIDE 7
ATRAC-X streaming in more detail
Frame1 Frame2 Frame3 Frame4 Frame5 Frame6
ATRAC-X 8kbps
Frame1 Frame2 Frame3 Frame4 Frame5 Frame6
ATRAC-X 128kbps
Frame1 Frame2 Frame1 Frame2 Frame3 Frame4 Frame3 Frame4 Frame3 Frame4 Frame3 Frame4
ATRAC-X Slot(1) ATRAC-X Slot(2) ATRAC-X Slot(3)
ATRAC-X Segment(1) ATRAC-X Segment(2) ATRAC-X Segment(1) ATRAC-X Segment(2) ATRAC-X Segment(2) ATRAC-X Segment(1)
SLIDE 8
Stream Example
ATRAC-X Slot -Nth- ATRAC-X Slot -N+1th- Segment (1) Segment (2) Segment (1) Segment (2) ATRAC-X 8kpbs FRSEQNO : N StreamID : 0 Priority : 1 NF = 2 ATRAC-X 128kpbs FRSEQNO : N StreamID : 1 Priority : 0 NF = 2 ATRAC-X 128kpbs FRSEQNO : N+1 StreamID : 1 Priority : 0 NF = 3 ATRAC-X 8kpbs FRSEQNO : N+1 StreamID : 0 Priority : 1 NF = 3
Transmission of two ATRAC-X streams in one ATRAC-X RTP session
SLIDE 9
Sketch of Redundant Data Payload Format
RTP Header
Current Data (Metadata & ATRAC-X Data Of Current ATRAC-X Slot) Redundant Data (Metadata & ATRAC-X Data Of Previous ATRAC-X Slot)
SLIDE 10
Fragmentation Example
ATRAC-X Slot
- Nth-
Segment (1) Segment (2) Segment (3) (1 packet) (1 packet) (2 packets)
ATRAC-X 8kbps C : 0 FragNo : 0 ATRAC-X 64kbps C : 0 FragNo : 0 ATRAC-X 240kbps C : 1 FragNo : 0 ATRAC-X 240kbps C : 0 FragNo : 1
SLIDE 11
Open Issues for AVT WG
- Metadata ID allocation – is this reasonable?
– How should we handle static IDs?
- How should timestamp information within