diff options
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/pcm2pdm.py | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/tools/pcm2pdm.py b/tools/pcm2pdm.py index 4279eb2..9c19927 100644 --- a/tools/pcm2pdm.py +++ b/tools/pcm2pdm.py @@ -2,8 +2,6 @@ import numpy as np import soundfile def second_order_delta_sigma(pcm): - # Normalize input XXX: remove normalization - #pcm = pcm / np.max(np.abs(pcm)) n = len(pcm) pdm = np.zeros(n, dtype=np.uint8) @@ -25,19 +23,37 @@ def second_order_delta_sigma(pcm): return pdm -def save_pdm_bin(pdm_data, file): - packed = np.packbits(pdm_data) - file.write(packed) +def first_order_delta_sigma(pcm): + n = len(pcm) + pdm = np.zeros(n, dtype=np.uint8) + integrator = 0.0 + quantized = 0.0 + for i in range(n): + integrator += pcm[i] - quantized + if integrator >= 0: + quantized = 1.0 + pdm[i] = 1 + else: + quantized = -1.0 + pdm[i] = 0 + return pdm -def convert(pcm_data, oversample = 64): +def convert(pcm_data, oversample = 64, order=2): # Oversample pcm_upsampled = np.repeat(pcm_data, oversample) # --- Convert to PDM --- - pdm_data = second_order_delta_sigma(pcm_upsampled) + if order == 1: + pdm_data = first_order_delta_sigma(pcm_upsampled) + elif order == 2: + pdm_data = second_order_delta_sigma(pcm_upsampled) return pdm_data +def save_pdm_bin(pdm_data, file): + packed = np.packbits(pdm_data) + file.write(packed) + def convert_file(input_file, **kwargs): # --- Load audio --- pcm_data, samplerate = soundfile.read(input_file) |