MELP - Mixed Excitation Linear Predictive

Department of Defense (DoD) Speech Coding Standard

Suitable for band limited or efficiency limited communication systems such as satellite links and military applications.

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Features List

  • Functions are C-callable

  • Multiple channel capable

  • NATO standard codec

  • Efficient in computational requirements

MELP DoD standard specifies a 2400 bps mode of operation.
MELPe is a triple-rate low codec that supports rates of 600 bps, 1200 bps, and 2400 bps. 

Coding Rate: 2.4 kbps
Sampling Rate: 8 kHz
 

Availability

Platforms
Arm ® Devices – Cortex-A8 / A9 / A15 | Cortex-M4 / M7 || Legacy ARM9E
Texas Instruments – TI TMS320C6000 C64x/C64x+/C66x, C674x, C62/C67 | TMS320C5000 C55x

ADT MELP is available on the above Platforms: Other configurations are available upon request.

Specifications

TMS320C6000

MELP C6x- C62x, C64x, C67x

CPU UTILIZATION & MEMORY REQUIREMENTS
All Memory usage is given in units of byte
FunctionMIPSProgram MemoryData MemoryScratch MemoryPer-Channel Data Memory
Encode21.2533121928030802480
Decode14.757632904
Encode / Decode35.8612483384

MELP C64x+ / C66x / C674x

CPU UTILIZATION & MEMORY REQUIREMENTS
All Memory usage is given in units of byte
FunctionMIPSProgram MemoryData MemoryScratch MemoryPer-Channel Data Memory
Encode21.2590564028130802480
Decode9.35832939005904
Encode / Decode30.5654897402973384

TMS320C5000

MELP C55x

CPU UTILIZATION & MEMORY REQUIREMENTS
All Memory usage is given in units of byte
FunctionMIPSProgram MemoryData MemoryScratch MemoryPer-Channel Data Memory
Encoder24.3213721945630802480
Decoder15.11376896

MELP ARM Cortex-A – ARMv7 | ARMv8

CPU UTILIZATION
MIPSMIPS (600bps)MIPS (1200bps)MIPS (2400bps)
Encoder464427
Decoder171717

MELP ARM Cortex-M4 | M7

CPU UTILIZATION
MIPSMIPS (600bps)MIPS (1200bps)MIPS (2400bps)
Encoder< 60< 50< 50
Decoder< 30< 30< 25

MEMORY REQUIREMENTS
All Memory usage is given in units of byte
Cortex-M4 FunctionProgramChannelScratchTablesData
Encoder100 k65606984148 k63 k
Decoder1376

Description

MELP Speech Coder was developed by the US military based upon the LPC-based CELP standard vocoder for low-bitrate communications. It is very efficient in its computational requirements. This translates into relatively low power consumption, an important consideration for portable systems. 

MELP codec is robust in difficult background noise environments such as found in military communications. 

MELP is used mainly in military applications and satellite communications, secure voice, and secure radio devices.

Function API's

API function call summary

InitializeMelpEncoderChannel (. . .) Initializes the MELP encoder
InitializeMelpDecoderChannel (. . .) Initializes the MELP decoder
EncodeMelp (. . .) Executes the MELP encoder
DecodeMelp (. . .) Executes the MELP decoder

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