CT8021 H.32x G.723.1/G.728 TrueSpeech Co-Processor Introduction Features The CT8021 is a speech co-processor which · TrueSpeechâ G.723.1 at 6.3, 5.3, 4.8 and performs full duplex speech compression and de- 4.1 kbps at 8KHz sampling rate (including compression functions. It provides speech G.723.1 Annex A VAD/CNG) compression for H.320, H.323 and H.324 · G.728 16 Kbps LD-CELP Multimedia Visual Telephony / Video · Download of additional speech compression Conferencing products and DSVD Modems. The software modules into external sram for CT8021 has built-in TrueSpeechâ G.723.1 (for TrueSpeechâ 8.5, G.722 & G.729-A/B H.323 and H.324) as well as G.728 LD-CELP · Real-time Full duplex or Half duplex speech speech compression (for H.320). This combination compression and decompression of ITU speech compression standards within a · Acoustic Echo Cancellation concurrent with single device enables the creation of a single full-duplex speech compression multimedia terminal which can operate in all · Full Duplex standalone Speakerphone types of Video Conferencing systems including · Host-to-Host (codec-less) and Host-CODEC H.320 ISDN-based, H.324 POTS-based, and modes of operation H.323 LAN/Internet-based. TrueSpeechâ G.723.1 · Parallel 8-bit host interface provides simple provides compressed data rates of 6.3 and 5.3 memory-mapped I/O host connection. Kbps and includes G.723.1 Annex A VAD/CNG · 1 or 2-channel DMA support (Single Cycle “silence” compression which can supply an even and Burst Modes) lower average bit rate. The CT8021 provides an · Flexible A-to-D/D-to-A CODEC interface, additional two non-ITU TrueSpeechâ data rates low cost PCM m/A-Law and 16-bit Linear at 4.8 and 4.1 Kbps. G.728 provides LD-CELP · CODEC interface supports TDM bus speech compression at 16 Kbps. The CT8021 also connection supports download of additional speech · Automatic handling of frame slippage and compression software modules into low cost frame synchronization external memory (e.g. TrueSpeechâ 8.5, G.722 · Automatic AGC for message recording and G.729A/B). The CT8021 is designed to · Speech level detection for silence operate as a micro-processor peripheral device compression support and co-exist with other devices such as modem- · DTMF and Tone Generation datapump and video compression chipsets. In · DTMF and Programmable Tone Detection addition the CT8021 includes built-in Acoustical Echo Cancellation which complements the speech · Pass-through modes - 8-bit and 16-bit linear compression functions by providing concurrent at 8 KHz and 11 KHz (host programmable hands-free operation. -continued on pg. 2 codec sample rate) and G.711 m/A-Law · Power Down and Power Save modes Phone Line System Modem Data Pump DAA Controller and Phone Hand/Head-set Interface Microphone & Microphone Video CT8021 Speaker SRAM Sub-system TrueSpeechâ Interface Speaker Co-Processor PRELIMINARY CT8021 System Block Diagram Version 1.1 DSP Group, Inc. The TrueSpeechâ G.723.1 algorithm delivers very highly compressed speech without compromising the speech quality. TrueSpeechâ G.723.1 at the 6.3 bit-rate has a MOS score of 3.9 for use with the ITU H.324 and H.323 standards. G.728 LD-CELP provides slightly higher speech quality but at the higher bit rate of 16 Kbits/sec as required by the ITU H.320 ISDN-based Video Conferencing Standard. The CT8021, an Application Specific Digital Signal Processor, is controlled by the system’s host processor through a simple host interface command protocol. The host interface supports full-duplex data transfer using DMA as well as host-interrupt and host-polling modes. The CT8021 supports two modes of uncompressed speech input/output. In HOST-CODEC mode, the uncompressed speech input/output is provided by one of the external serial codecs. In HOST-HOST (codec-less) mode, the Host provides the uncompressed speech input/output via the host interface. The only additional external component ICs needed to implement these functions are two low cost 8Kx8 or 32Kx8 SRAMs, a CODEC and oscillator crystal circuit. Note: MOS, Mean Opinion Score is a subjective measure of speech quality where a score of 5 means that the speech quality is Excellent, 4 is Good or Toll Quality (as expected in PSTN) and 3 is fair. Applications · Simultaneous Voice and Data Modems · Voice Enabled Wireless Terminals · Teleconferencing and Video Conferencing · Store & Forward applications for speech · CTI - Computer-Telephony Applications · Desktop Telephony & Speakerphone · Digital Telephony Applications · Internet Telephony Applications CT8021 Functional Block Diagram Host Interface Host Interface Frame Buffering Frame Buffering Speech Speech Encoder Decoder DTMF & Tone Input Volume Output Volume Detector Control Control GPIO Line Echo Programmable Echo Suppressor & Canceller Acoustic Echo Cancellor CODEC CODEC DTMF & Tone Interface Interface Generator CODEC CODEC Data/Program SRAM (optional telephone line connection) Speaker/Microphone connection 8K or 32K x 16 CT8021A11AQC: Firmware Revision 0115 PRELIMINARY Version 1.1 DSP Group Inc. i TABLE OF CONTENTS 1. PIN-OUT AND DESCRIPTIONS.................................................................................................. 1-1 2. EXTERNAL COMPONENT CONNECTIONS............................................................................ 2-1 2.1 PLL CIRCUIT.................................................................................................................................... 2-1 2.2 CT8021 EXTERNAL SRAM CONNECTIONS....................................................................................... 2-2 2.2.1 CT8021 16-bit external data only SRAM connection........................................................... 2-3 2.2.2 CT8021 16-bit combined program-data (download) SRAM connection.............................. 2-4 2.3 CODEC CONNECTION........................................................................................................................ 2-5 3. FEATURE OVERVIEW................................................................................................................ 3-1 3.1 INTRODUCTION................................................................................................................................. 3-1 3.2 SPEECH MODES................................................................................................................................ 3-2 3.3 G.728 LD-CELP.............................................................................................................................. 3-3 3.4 TRUESPEECH.................................................................................................................................... 3-3 3.5 TRUESPEECH 6.3 ( G.723.1)............................................................................................................. 3-4 3.6 TRUESPEECH 5.3 (G.723.1).............................................................................................................. 3-4 3.7 TRUESPEECH 4.8.............................................................................................................................. 3-4 3.8 TRUESPEECH 4.1.............................................................................................................................. 3-4 3.9 G.711 MU-LAW/A-LAW.................................................................................................................... 3-4 3.10 TRUESPEECH 8.5 DOWNLOAD-ABLE............................................................................................... 3-5 3.11 G.729 ANNEX A DOWNLOAD-ABLE............................................................................................... 3-5 3.12 G.722 DOWNLOAD-ABLE................................................................................................................ 3-5 3.13 AUTOMATIC GAIN CONTROL.......................................................................................................... 3-5 3.14 RECORD & PLAYBACK VOLUME..................................................................................................... 3-5 3.15 DSVD............................................................................................................................................ 3-5 3.16 MICROSOFT WINDOWS SOUND SYSTEM.......................................................................................... 3-6 3.17 SPEECH DATA COMPRESSION AND DECOMPRESSION ACCELERATOR................................................ 3-6 3.18 DTMF & TONE GENERATION......................................................................................................... 3-6 3.19 TONE DETECTION........................................................................................................................... 3-6 3.20 DTMF DETECTION......................................................................................................................... 3-7 3.21 FULL DUPLEX SPEAKERPHONE....................................................................................................... 3-7 3.22 ACOUSTIC ECHO CANCELLOR......................................................................................................... 3-7 3.23 8 OR 16-BIT HOST CONTROLLER INTERFACE.................................................................................... 3-8 3.24 CODEC INTERFACE....................................................................................................................... 3-8 3.25 CT8021 CRYSTAL.........................................................................................................................