Error Tolerant AMR Speech Payload

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Error Tolerant AMR Speech Payload
ltdraft-xie-avt-et-rtp-amr-02.txtgt Qiaobing
Xie Motorola, Inc. Email ltQXIE1_at_email.mot.comgt
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Design Principles

1. Tolerant to bit errors in the speech data and
   dynamic rate change are two most
   importantfeatures of AMR codec. The AMR-over-IP
   payload design must support both.
2. The design should not limit itself to only
   wireless cases, but should bring the benefitsof
   AMR to general VoIP applications.

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AMR Error Handling Requirements
headers
class A
class B/C
(no error checking on class B/C bits)
headers
headers
headers
class A
class A
class A
class B/C
class B/C
class B/C
Case 1 No error detected Action
Full decoding
Case 2 Error detected in Class A
bits Action Partial decoding
Case 3 Error detected in
Headers Action Discard packet
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Error Tolerant AMR Payload Design
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Error Tolerant AMR Payload Design (cont.)
AMR payload header
frame header TOC
Class A bits
Class B and C bits
A flag 0 full AMR frame 1 Class A bits
only Q flag 0 error detected in Class A bits
1 not error detected C flag 0 no Codec CRC
field 1 Codec CRC present
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Why Need Error Tolerant?
AMR IP Phone
AMR IP Phone
Low cost ET access link (wire-line or wireless)
AMR IP Phone