1 / 10

An RTP Payload Format for EVRC Speech draft-3gpp2-avt-evrc-01.txt

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

iman
Download Presentation

An RTP Payload Format for EVRC Speech draft-3gpp2-avt-evrc-01.txt

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An RTP Payload Format for EVRC Speechdraft-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 PureVoiceä (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 1. Interleaving / bundling 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] | +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ |RR | LLL | NNN | | +-+-+-+-+-+-+-+-+ one or more codec data frames + | .... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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 2. Single codec data format – Interleaving/bundling disabled 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 +-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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?

More Related