We have downloaded version 4.4 EVRC-B fixed point code from
ftp://ftp.3gpp2.org/TSGC/Incoming/SWG11/evrc_rel-C_mps_software/
We find two problems with this code. They are:
1. We find that the output of the encoder doesn’t match with the expected
output for Operating point-2 and signal power 22 and 32 dB (i.e. we used the
command line options -i src.s22 -o 4_8.p22 -X OP=2 –e and -i src.s32 -o
5_8.p32 -X OP=2 –e). We have similar problem with 32dB signal at
operating point-0 as well (-i src.s32 -o 9_3.p32 -X OP=0 –e). We found
this problem with recent version 4.4 as well as earlier versions downloaded from
3GPP site.
2. There seems to be an error in the implementation of r-fft function in this
code. It results in non-zero imaginary value for the first data point, whereas
the first point of the DFT of a real sequence should be real. It appears that
there is an error in the r-fft function where the real and imaginary values of
the first point are computed outside the loop.
I would highly appreciate if anyone having information on these issues of this
code could help me out.
Thanks in advance.
Venu
