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====================================================================================
EVS Codec 3GPP TS26.442 Sep 15, 2014. Version 12.0.0
====================================================================================
These files represent the 3GPP EVS Codec BASOP C simulation.
All code is written in ANSI-C. The system is implemented as two separate
programs:
EVS_cod Encoder
EVS_dec Decoder
For encoding using the coder program, the input is a binary
audio file (*.8k, *.16k, *.32k, *.48k) and the output is a binary
encoded parameter file (*.192). For decoding using the decoder program,
the input is a binary parameter file (*.192) and the output is a binary
synthesized audio file (*.8k, *.16k, *.32k, *.48k).
FILE FORMATS:
=============
The file format of the supplied binary data (*.8k, *.16k, *.32k, *.48k,
*.192) is 16-bit binary data which is read and written in 16 bit words.
The data is therefore platform DEPENDENT.
The files contain only data, i.e., there is no header.
The test files included in this package are "PC" format, meaning that the
least signification byte of the 16-bit word comes first in the files.
If the software is to be run on some other platform than PC,
such as an HP (HP-UX) or a Sun, then binary files will need to be modified
by swapping the byte order in the files.
The input and output files (*.8k, 16k, 32k, 48k) are 16-bit signed
binary files with 8/16/32/48 kHz sampling rate with no headers.
The Encoder produces bitstream files which are as follows:
For every 20 ms input audio frame, the encoded bitstream using ITU
G.192 format contains the following data:
Using ITU G.192 format:
Word16 SyncWord
Word16 DataLen
Word16 1st Databit
Word16 2nd DataBit
.
.
.
Word16 Nth DataBit
The SyncWord from the encoder is always 0x6b21. If decoder receives SyncWord as 0x6b20
it indicates that the current frame was received in error (bad frame).
The DataLen parameter gives the number of audio data bits in the frame. For example using
DTX, DataLen for NO_DATA frames is zero.
Each bit is presented as follows: Bit 0 = 0x007f, Bit 1 = 0x0081.
INSTALLING THE SOFTWARE
=======================
Installing the software on the PC:
First unpack the compressed folder into your directory. After that you
should have the following structure:
.
`-- c-code
|-- Makefile
|-- Workspace_msvc
|-- basic_math
|-- basic_op
|-- lib_com
|-- lib_dec
|-- lib_enc
`-- readme.txt
The package includes a Makefile for gcc, which has been verified on
32-bit Linux systems. The code can be compiled by entering the directory
"c-code" and typing the command: make. The resulting encoder/decoder
executables are named "EVS_cod" and "EVS_dec". Both reside in the c-code
directory.
The package also includes solution-file for Microsoft Visual
Studio 2008 (x86). To compile the code, please open
"Workspace_msvc\Workspace_msvc.sln", and build "evs_enc" for the encoder
and "evs_dec" for the decoder executable. The resulting encoder/decoder
executables are named "EVS_cod.exe" and "EVS_dec.exe". Both reside in the c-code
directory.
RUNNING THE SOFTWARE
====================
The usage of the "EVS_cod" program is as follows:
Usage:
EVS_cod [Options] R Fs input_file bitstream_file
Mandatory parameters:
---------------------
R : Bitrate in bps,
for EVS native modes R = (5900*, 7200, 8000, 9600, 13200, 16400,
24400, 32000, 48000, 64000, 96000, 128000)
*VBR mode (average bitrate),
for AMR-WB IO modes R = (6600, 8850, 12650, 14250, 15850, 18250,
19850, 23050, 23850)
Alternatively, R can be a bitrate switching file which consits of R values
indicating the bitrate for each frame in bit/s. These values are stored in
binary format using 4 bytes per value
Fs : Input sampling rate in kHz, Fs = (8, 16, 32 or 48)
input_file : Input signal filename (*.8k, *.16k, *.32k, *.48k)
bitstream_file : Output bitstream filename (*.192)
Options:
--------
-q : Quiet mode, no frame counters
default is deactivated
-dtx D : Activate DTX mode, D = (0, 3-100) is the SID update rate
where 0 = adaptive, 3-100 = fixed in number of frames,
default is deactivated
-dtx : Activate DTX mode with a SID update rate of 8 frames
-rf p o : Activate channel-aware mode for WB and SWB signal at 13.2kbps,
where FEC indicator, p: LO or HI, and FEC offset, o: 2, 3, 5, or 7 in number of frames.
Alternatively p and o can be replaced by a rf configuration file with each line
contains the values of p and o separated by a space,
default is deactivated
-max_band B : Activate bandwidth limitation, B = (NB, WB, SWB or FB)
alternatively, B can be a text file where each line contains
"nb_frames B"
The usage of the "EVS_dec" program is as follows:
Usage:
EVS_dec [Options] Fs bitstream_file output_file
Mandatory parameters:
---------------------
Fs : Output sampling rate in kHz (8, 16, 32 or 48)
bitstream_file : Input bitstream filename (*.192) or RTP packet filename (in VOIP mode)
output_file : Output audio filename (*.8k, *.16k, *.32k, *.48k)
Options:
--------
-q : Quiet mode, no frame counter
default is deactivated
-VOIP : Activate VOIP mode
default is deactivated
-fec_cfg_file : Output of the channel aware configuration. The outptut is
written into a .txt file. Each line contains the FER indicator
(HI|LO) and optimum FEC offset.
-Tracefile TF : Generate trace file named TF (used only when -VOIP is activated)
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evs codec with transmission module
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