automated test for FreeDV resampler

CMakeLists.txt

@@ -22,6 +22,12 @@ set(FRAMESPERBURST 3)
 set(BURSTS 1)
 set(TESTFRAMES 3)
 
+add_test(NAME 000_resampler
+         COMMAND sh -c "export LD_LIBRARY_PATH=${CODEC2_BUILD_DIR}/src;
+                        cd ${CMAKE_CURRENT_SOURCE_DIR}/test/000_resampler;
+                        python3 t48_8_short.py")
+        set_tests_properties(000_resampler PROPERTIES PASS_REGULAR_EXPRESSION "PASS")
+
 add_test(NAME 001_highsnr_stdio_P_C_SM
          COMMAND sh -c "export LD_LIBRARY_PATH=${CODEC2_BUILD_DIR}/src;
                         PATH=$PATH:${CODEC2_BUILD_DIR}/src;

test/000_resampler/t48_8_short.py

@@ -38,25 +38,72 @@ AMP      = 16000                      # sine wave amplitude
 FTEST8   = 800                        # input test frequency at FS=8kHz
 FINTER48 = 10000                      # interferer frequency at FS=48kHz
 
+# Due to the design of these resamplers, the processing buffer (at 8kHz)
+# must be an integer multiple of oversampling ratio
+assert N8 % FDMDV_OS_48 == 0
+
 in8k = np.zeros(MEM8 + N8, dtype=np.int16)
 out48k = np.zeros(N48, dtype=np.int16)
 in48k = np.zeros(MEM48 + N48, dtype=np.int16)
 out8k = np.zeros(N8, dtype=np.int16)
 
+# time indexes, we advance every frame
 t = 0
+t1 = 0
+
 fin8 = open("in8.raw", mode='wb')
 f48 = open("out48.raw", mode='wb')
+fout8 = open("out8.raw", mode='wb')
 
 for f in range(FRAMES):
-    
+
+    # input sine wave
     in8k[MEM8:] = AMP*np.cos(2*np.pi*np.arange(t,t+N8)*FTEST8/FS8)
     t += N8
     in8k[MEM8:].tofile(fin8)
 
+    # upsample
     pin8k,flag = in8k.__array_interface__['data']
     pin8k += 2*MEM8
     codec2.api.fdmdv_8_to_48_short(out48k.ctypes, pin8k, N8);
     out48k.tofile(f48)
 
+    # add interfering sine wave (down sampling filter should remove)
+    in48k[MEM48:] = out48k + (AMP/2)*np.cos(2*np.pi*np.arange(t1,t1+N48)*FINTER48/FS48)
+    t1 += N48
+
+    # downsample
+    pin48k,flag = in48k.__array_interface__['data']
+    pin48k += 2*MEM48
+    codec2.api.fdmdv_48_to_8_short(out8k.ctypes, pin48k, N8);
+    out8k.tofile(fout8)
+
 fin8.close()
 f48.close()
+fout8.close()
+
+# Automated test evaluation --------------------------------------------
+
+# The input and output signals will not be time aligned due to the filter
+# delays, so compare the magnitude spectrum
+
+in8k = np.fromfile("in8.raw", dtype=np.int16)
+out8k = np.fromfile("out8.raw", dtype=np.int16)
+assert len(in8k) == len(out8k)
+
+n = len(in8k)
+
+h = np.hanning(len(in8k))
+S1 = np.abs(np.fft.fft(in8k * h))
+S2 = np.abs(np.fft.fft(out8k * h))
+
+error = S1-S2
+error_energy = np.dot(error,error)
+ratio = error_energy/np.dot(S1,S1)
+ratio_dB = 10*np.log10(ratio);
+print("ratio_dB: %4.2f" % (ratio_dB));
+threshdB = -40
+if ratio_dB < threshdB:
+    print("PASS")
+else:
+    print("FAIL")

test/001_highsnr_stdio_audio/test_tx.py

@@ -1,4 +1,4 @@
- #!/usr/bin/env python3
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 
@@ -7,8 +7,6 @@ from ctypes import *
 import pathlib
 import pyaudio
 import time
-import threading
-import audioop
 import argparse
 import sys
 sys.path.insert(0,'..')