5 Test sequence format

06.073GPPHalf Rate Speech: Test Sequence for GSM Half Rate Speech CodecTS

This clause provides information on the format of the digital test sequences for the GSM half rate speech transcoder (GSM 06.20 [2]), Voice Activity Detector (GSM 06.42 [6]), comfort noise (GSM 06.22 [4]) and the discontinuous transmission (GSM 06.41 [5]).

5.1 File format

The test sequence files are provided in archive en_300968v080001p0.ZIP which accompanies the present document.

Following decompression, by execution of the 11 "disk*.exe" files, four types of file are provided:

‑ Files for input to the GSM half rate speech encoder: *.INP

‑ Files for comparison with the encoder output: *.COD

‑ Files for input to the GSM half rate speech decoder: *.DEC

‑ Files for comparison with the decoder output: *.OUT

Tables 1, 2, 3 and 4 define the formats of the four types of file. Each parameter in these tables is contained in a 16 bit word except for the samples of the 8 bit PCM test sequences, which are contained in an 8 bit word each. The left or right justification is indicated in the tables. The size and location of speech parameters in the encoder output (*.COD) and decoder input files (*.DEC) are described in GSM 06.20 [2].

5.2 Codec homing

Each *.INP file includes two homing frames at the start of the test sequence. The function of these frames is to reset the speech encoder state variables to their initial value. In the case of a correct installation of the ANSI‑C simulation (GSM 06.06 [7]), all speech encoder output frames shall be identical to the corresponding frame in the *.COD file. In the case of a correct hardware implementation undergoing type approval, the first speech encoder output frame is undefined and need not be identical to the first frame in the *.COD file, but all remaining speech encoder output frames shall be identical to the corresponding frames in the *.COD file.

Each *.DEC file includes two homing frames at the start of the test sequence. The function of these frames is to reset the speech decoder state variables to their initial value. In the case of a correct installation of the ANSI‑C simulation (GSM 06.06 [7]), all speech decoder output frames shall be identical to the corresponding frame in the *.OUT file. In the case of a correct hardware implementation undergoing type approval, the first speech decoder output frame is undefined and need not be identical to first frame in the *.OUT file, but all remaining speech decoder output frames shall be identical to the corresponding frames in the *.OUT file.

Table 1: Encoder input sequence (*.INP) format

Name

Description

No. of bits

Justification

s(n)

Encoder input signal

13

Left

Table 2: Encoder output sequence (*.COD) format

Name

Description

No. of words

Justification

Speech

Speech parameters to the channel encoder

18

Right

Additional information

VAD

SP

Voice activity detection flag

SP flag

1

1

Right

Right

Table 3: Decoder input sequence (*.DEC) format

Name

Description

No. of bits/words

Justification

Speech parameters

Speech parameters to the channel encoder

18 words

Right

BFI flag

UFI flag

SID flag

TAF flag

Bad Frame Indicator

Unreliable Frame Indicator

SIlence Descriptor

Time Alignment Flag

1 bit / 1 word

1 bit / 1 word

2 bits / 1 word

1 bit / 1 word

Right

Right

Right

Right

Table 4: Decoder output sequence (*.OUT) format

Name

Description

No. of bits

Justification

s'(n)

Decoder output signal

13

Left