Test SNR under different frequencies and samples.

tool/test_frequency_and_SNR.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+import wave
+import aifc
+sys.path.append("..")
+from se2m4a import *
+import matplotlib.pyplot as plt
+
+SNR_all = {}
+
+for audio_file in sys.argv[1:]:
+ SNR_audio = []
+ for freq in magic_rates:
+ audio_name, audio_ext = os.path.splitext(audio_file)
+ audio_freq = audio_name + "-" + str(freq) + audio_ext
+ os.system("sox " + audio_file + " -r " + str(freq) + " -b 8 -c 1 " + audio_freq)
+ if audio_ext in ('.wav', '.WAV'):
+ audio_module = wave
+ else:
+ audio_module = aifc
+ with audio_module.open(audio_freq, 'rb') as audio:
+ frames = audio.getnframes()
+ raw = audio.readframes(frames)
+ if audio_module == wave:
+ uncompressed_data = (np.frombuffer(raw, dtype = np.ubyte) - 0x80).astype(np.byte)
+ else:
+ uncompressed_data = np.frombuffer(raw, dtype = np.byte)
+ compressed_data, decompressed_data = compress(uncompressed_data)
+ SNR = calculate_SNR(uncompressed_data, decompressed_data)
+ SNR_audio.append(SNR)
+ SNR_all[os.path.split(audio_file)[-1]] = SNR_audio
+
+plt.title('SNR-Frequency')
+plt.xlabel('freq/Hz')
+plt.ylabel('SNR/dB')
+plt.xticks(magic_rates)
+plt.xticks(rotation=-30)
+for audio, SNR in SNR_all.items():
+ plt.plot(magic_rates, SNR, label = audio)
+plt.legend(loc='center left', bbox_to_anchor=(1, 0.5))
+plt.tight_layout()
+plt.show()