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108 lines
No EOL
4.2 KiB
Python
108 lines
No EOL
4.2 KiB
Python
"""
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/* Copyright (c) 2022 Amazon
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Written by Jan Buethe */
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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"""
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import numpy as np
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def write_fec_packets(filename, packets, rates=None):
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""" writes packets in binary format """
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assert np.dtype(np.float32).itemsize == 4
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assert np.dtype(np.int16).itemsize == 2
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# derive some sizes
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num_packets = len(packets)
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subframes_per_packet = packets[0].shape[-2]
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num_features = packets[0].shape[-1]
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# size of float is 4
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subframe_size = num_features * 4
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packet_size = subframe_size * subframes_per_packet + 2 # two bytes for rate
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version = 1
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# header size (version, header_size, num_packets, packet_size, subframe_size, subrames_per_packet, num_features)
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header_size = 14
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with open(filename, 'wb') as f:
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# header
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f.write(np.int16(version).tobytes())
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f.write(np.int16(header_size).tobytes())
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f.write(np.int16(num_packets).tobytes())
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f.write(np.int16(packet_size).tobytes())
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f.write(np.int16(subframe_size).tobytes())
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f.write(np.int16(subframes_per_packet).tobytes())
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f.write(np.int16(num_features).tobytes())
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# packets
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for i, packet in enumerate(packets):
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if type(rates) == type(None):
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rate = 0
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else:
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rate = rates[i]
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f.write(np.int16(rate).tobytes())
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features = np.flip(packet, axis=-2)
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f.write(features.astype(np.float32).tobytes())
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def read_fec_packets(filename):
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""" reads packets from binary format """
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assert np.dtype(np.float32).itemsize == 4
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assert np.dtype(np.int16).itemsize == 2
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with open(filename, 'rb') as f:
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# header
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version = np.frombuffer(f.read(2), dtype=np.int16).item()
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header_size = np.frombuffer(f.read(2), dtype=np.int16).item()
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num_packets = np.frombuffer(f.read(2), dtype=np.int16).item()
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packet_size = np.frombuffer(f.read(2), dtype=np.int16).item()
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subframe_size = np.frombuffer(f.read(2), dtype=np.int16).item()
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subframes_per_packet = np.frombuffer(f.read(2), dtype=np.int16).item()
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num_features = np.frombuffer(f.read(2), dtype=np.int16).item()
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dummy_features = np.zeros((subframes_per_packet, num_features), dtype=np.float32)
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# packets
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rates = []
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packets = []
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for i in range(num_packets):
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rate = np.frombuffer(f.read(2), dtype=np.int16).item
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rates.append(rate)
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features = np.reshape(np.frombuffer(f.read(subframe_size * subframes_per_packet), dtype=np.float32), dummy_features.shape)
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packet = np.flip(features, axis=-2)
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packets.append(packet)
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return packets |