G.711¶
Introduction¶
G.711 is an ITU-T standard for audio companding: Pulse code modulation (PCM) of voice frequencies.
Source Code¶
This codec is based on the original G.711, 25 November 1988, corresponding ANSI-C code is available in the G.711 module of the ITU-T G.191 Software Tools Library, 13 January 2019, and this codec passes the test cases successfully.
Multi-instance and reentrance¶
Codec hasn’t tested on multi-instance run, for more information about support of
multi-instance run see codec source documentation. Codec supports reentrance
in case if AGU address pointer registers (AGU_AUX_APx), AGU offset registers (AGU_AUX_OSx),
AGU modifier registers (AGU_AUX_MODx), see [1] in References, will be saved and restored.
Codec-Specific Build Options¶
LTO_BUILD and REMAPITU_T options are not available for this codec. Use the following command to build the G.711 codec:
mdb -run -cl -nsim -tcf=<default TCF from /rules/common_hw_config.mk> g711demo.elf <number of frames> [u|A] [-r] [lili|loli|lilo] <input_file> <output_file> <BlockSize> <1stBlock> <NoOfBlocks> [-skip n]
The following table lists the G.711 codec parameters
| Option | Description |
|---|---|
<input_file> |
Specifies the input file |
<output_file> |
Specifies the output file |
-r |
Disables even-bit swap by A-law encoding and decoding (DEFAULT) |
A |
Input data for encoding and output data for decoding are in α-law (G.711) format |
u |
Input data for encoding and output data for decoding are in µ-law (G.711) format |
lili |
Convert the input file linear to linear: lin -> (A/u)log -> lin |
lilo |
Convert the input file linear to (A/u)-log |
loli |
Convert the input file (A/u) log to linear |
<BlockSize> |
Number of samples per block [256] (optional) |
<1stBlock> |
Number of the first block of the input file to be processed (optional) |
<NoOfBlocks> |
Number of blocks to process, starting with block <1stBlock> |
-skip *n* |
n is the number of samples to skip (optional) |
Examples
The following command converts the linear samples to A-law log:
mdb -run -cl -nsim -tcf=em9d_voice_audio g711demo.elf A lilo ../testvectors/Ref/sweep.src ../testvectors/sweep-r.a 256 1 256
The following command converts from A-law log to linear samples:
mdb -run -cl -nsim -tcf=em9d_voice_audio g711demo.elf A loli ../testvectors/Ref/sweep-r.a ../testvectors/sweep.src 256 1 256