7 DTX test sequences
3GPP46.054Release 17Test sequences for the GSM Enhanced Full Rate (EFR) speech codecTS
This subclause describes the test sequences designed to exercise the VAD algorithm (GSM 06.82 [6]), comfort noise (GSM 06.62 [4]) and discontinuous transmission (GSM 06.81 [5]).
7.1 Codec configuration
The VAD, comfort noise and discontinuous transmission shall be tested in conjunction with the speech encoder (GSM 06.60 [2]). The speech encoder shall be configured to operate in the DTX mode defined in GSM 06.62 [4].
7.2 DTX test sequences
Each DTX test sequence consists of four files:
– Files for input to the GSM enhanced full rate speech encoder: *.INP
– Files for comparison with the encoder output: *.COD
– Files for input to the GSM enhanced full rate speech decoder: *.DEC
– Files for comparison with the decoder output: *.OUT
The *.DEC files are generated from the corresponding *.COD files.
In a correct implementation, the speech encoder parameters generated by the *.INP file shall be identical to those specified in the *.COD file; and the speech decoder output generated by the *.DEC file shall be identical to that specified in the *.OUT file.
Table 6 lists the DTX test sequences and their size in frames.
7.2.1 Predictor values computation
The computation of the predictor values described in GSM 06.82 [6] is not tested explicitly, since the results from the computation are tested many times via the spectral comparison and threshold adaptation tests.
7.2.2 Spectral comparison
The spectral comparison algorithm described in GSM 06.82 [6] is tested by the following test sequence:
– DTX01. *
7.2.3 Threshold adaptation
The threshold adaptation algorithm described in GSM 06.82 [6] is tested by the following test sequence:
– DTX02. *
7.2.4 Periodicity detection
The periodicity detection algorithm described in GSM 06.82 [6] is tested by the following test sequence:
– DTX03. *
7.2.5 Tone detection
The tone detection algorithm described in GSM 06.82 [6] is tested by the following test sequence:
– DTX04. *
7.2.6 Safety and initialisation
This sequence checks the safety paths used to prevent zero values being passed to the norm function. It checks the functions described in the adaptive filtering and energy computation, and the prediction values computation given in GSM 06.82 [6]. This sequence also checks the initialisation of thvad and the rvad array:
– DTX05. *
7.2.7 Comfort noise test sequence
The test sequences described in sub-subclauses 7.2.2 to 7.2.6 are designed to exercise the VAD described in GSM 06.82 [6] and the discontinuous transmission described in GSM 06.81 [5]. The following test sequence is defined to exercise the comfort noise algorithm described in GSM 06.62 [4]:
– DTX06.*
7.2.8 Real speech and tones
The test sequences cannot be guaranteed to find every possible error. There is therefore a small possibility that an incorrect implementation produces the correct output for the test sequences, but fails with real signals. Consequently, an extra sequence is included, which consists of very clean speech, barely detectable speech and a swept frequency tone:
– DTX07. *
NOTE: Some of the DTX test sequences contain homing frames. The DTX test sequences are therefore only suitable for testing a single transcoding.
Table 6: Location and size of DTX test sequences
|
size |
(bytes) |
|||||
|
Disk No. |
File Name |
No. of Frames |
*.INP |
*.COD |
*.DEC |
*.OUT |
|
4/8 |
DTX01 |
710 |
227 200 |
349 320 |
350 740 |
227 200 |
|
4/8 |
DTX02 |
933 |
298 560 |
459 036 |
460 902 |
298 560 |
|
4/8 |
DTX03 |
156 |
49 920 |
76 752 |
77 064 |
49 920 |
|
4/8 |
DTX04 |
245 |
78 400 |
120 540 |
121 030 |
78 400 |
|
4/8 |
DTX05 |
56 |
17 920 |
27 552 |
27 664 |
17 920 |
|
4/8 |
DTX06 |
771 |
246 720 |
379 332 |
380 874 |
246 720 |
|
4/8 |
DTX07 |
1188 |
380 160 |
584 496 |
586 872 |
380 160 |