1. An RTP Payload Format for EVRC Speech draft-3gpp2-avt-evrc-01.txt by Lucent, Nokia, Qualcomm, Samsung and UCLA (alphabetic ordered)

2. EVRC codec Speech codec EIA / TIA IS-127 Used in cdma2000 applications Three different sizes of output frames Full rate (171 bits) 1/2 rate (80 bits) 1/8 rate (16 bits)

3. Application cdma2000 wireless voice telephone services cdma2000 video streaming services cdma2000 video conferencing services The packet-switched mode of the later two services requires an RTP payload format to be defined for EVRC codec data.

4. Combined Draft The differences with the submitted draft: Some textual clarifications Octet 0 of EVRC payload now has bit to support rate reduction Incorporated section from Lucent draft on MIME types and SDP parameters

5. Proposed payload format Follows format of RFC 2658 for PureVoice   13K celp) codec. Included format specifically for non- interleaved case (one codec data in each RTP packet) – save the 1 byte overhead. Included Rate Reduction bits – to signal requests for reducing the codec rate for the reverse direction.

6. RTP payload format for EVRC 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RTP Header [2] | +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ |RR | LLL | NNN | | +-+-+-+-+-+-+-+-+ one or more codec data frames + |.... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1. Interleaving / bundling format The interleaving byte : RR – Reserved (2 bits, must be 00) LLL – Interleave (3 bits) NNN – Interleave index (3 bits)

7. Codec data format 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |I|R| frame type| +-+-+-+-+-+-+-+-+ + codec data I – Interleaving disabled (1 bit) R – Reduce rate (1 bit) Frame type – (6 bits) Value RATE TOTAL CODEC data frame size (in octets) --------------------------------------------------------- 0 Blank 1 1 1/8 3 3 1/2 11 4 1 23 14 Erasure 1 (SHOULD NOT be transmitted by sender)

8. Single codec data format 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RTP Header [2] | +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ | + one codec data frames +-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2. Single codec data format – Interleaving/bundling disabled The interleaving byte is not present.

9. Misc issues The receiver can determine if the payload is interleaved by detecting the presence of 1 at the first bit of the RTP payload. The sender must not increasing the interleaving size LLL without changing SSRC. The sender must not switch from non- interleaved format to interleaved format without changing SSRC.

10. Comments, questions?