1. © NOKIAAMR_MIME.PPT / 29.03.2000 / AL page: 1 MIME type registration of AMR speech codec draft-lakaniemi-avt-mime-amr-00.txt draft-wimmer-avt-mime-amr-00.txt Ari Lakaniemi, Nokia Petri Koskelainen, Nokia Johan Sjöberg, Ericsson Bernard Hammer, Siemens

2. © NOKIAAMR_MIME.PPT / 29.03.2000 / AL page: 2 Overview of the AMR speech codec Adaptive Multi-Rate (AMR) speech codec is originally standardized by ETSI for the GSM system Selected by 3GPP as mandatory speech codec for 3rd generation WCDMA systems AMR speech codec operates on 20 ms frames at 8 kHz sampling frequency 8 speech coding modes in range 4.75 … 12.2 kbit/s seamless mode adaptation includes also DTX / comfort noise and lost frame compensation é AMR is expected to be a popular speech codec also in VoIP applications

3. © NOKIAAMR_MIME.PPT / 29.03.2000 / AL page: 3 MIME type registration of the AMR codec Registration of name audio/AMR from the IETF tree Support for RTP transport and storage (e.g. e-mail attachment, multimedia messaging) All eight AMR speech coding modes as mandatory features Optional features for RTP protocol: - PDC-EFR, IS-641 and GSM EFR CN - Possibility to limit the number of frames per packet - Possibility to request a subset of AMR modes - Possibility to set the minimum interval for mode changes - Possibility to limit mode changes to neighboring modes only AMR speech frame encapsulation is work in progress