1""" 2/* Copyright (c) 2022 Amazon 3 Written by Jan Buethe */ 4/* 5 Redistribution and use in source and binary forms, with or without 6 modification, are permitted provided that the following conditions 7 are met: 8 9 - Redistributions of source code must retain the above copyright 10 notice, this list of conditions and the following disclaimer. 11 12 - Redistributions in binary form must reproduce the above copyright 13 notice, this list of conditions and the following disclaimer in the 14 documentation and/or other materials provided with the distribution. 15 16 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER 20 OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 21 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 22 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 23 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 24 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 25 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 26 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27*/ 28""" 29 30import numpy as np 31 32 33 34def write_fec_packets(filename, packets, rates=None): 35 """ writes packets in binary format """ 36 37 assert np.dtype(np.float32).itemsize == 4 38 assert np.dtype(np.int16).itemsize == 2 39 40 # derive some sizes 41 num_packets = len(packets) 42 subframes_per_packet = packets[0].shape[-2] 43 num_features = packets[0].shape[-1] 44 45 # size of float is 4 46 subframe_size = num_features * 4 47 packet_size = subframe_size * subframes_per_packet + 2 # two bytes for rate 48 49 version = 1 50 # header size (version, header_size, num_packets, packet_size, subframe_size, subrames_per_packet, num_features) 51 header_size = 14 52 53 with open(filename, 'wb') as f: 54 55 # header 56 f.write(np.int16(version).tobytes()) 57 f.write(np.int16(header_size).tobytes()) 58 f.write(np.int16(num_packets).tobytes()) 59 f.write(np.int16(packet_size).tobytes()) 60 f.write(np.int16(subframe_size).tobytes()) 61 f.write(np.int16(subframes_per_packet).tobytes()) 62 f.write(np.int16(num_features).tobytes()) 63 64 # packets 65 for i, packet in enumerate(packets): 66 if type(rates) == type(None): 67 rate = 0 68 else: 69 rate = rates[i] 70 71 f.write(np.int16(rate).tobytes()) 72 73 features = np.flip(packet, axis=-2) 74 f.write(features.astype(np.float32).tobytes()) 75 76 77def read_fec_packets(filename): 78 """ reads packets from binary format """ 79 80 assert np.dtype(np.float32).itemsize == 4 81 assert np.dtype(np.int16).itemsize == 2 82 83 with open(filename, 'rb') as f: 84 85 # header 86 version = np.frombuffer(f.read(2), dtype=np.int16).item() 87 header_size = np.frombuffer(f.read(2), dtype=np.int16).item() 88 num_packets = np.frombuffer(f.read(2), dtype=np.int16).item() 89 packet_size = np.frombuffer(f.read(2), dtype=np.int16).item() 90 subframe_size = np.frombuffer(f.read(2), dtype=np.int16).item() 91 subframes_per_packet = np.frombuffer(f.read(2), dtype=np.int16).item() 92 num_features = np.frombuffer(f.read(2), dtype=np.int16).item() 93 94 dummy_features = np.zeros((subframes_per_packet, num_features), dtype=np.float32) 95 96 # packets 97 rates = [] 98 packets = [] 99 for i in range(num_packets): 100 101 rate = np.frombuffer(f.read(2), dtype=np.int16).item 102 rates.append(rate) 103 104 features = np.reshape(np.frombuffer(f.read(subframe_size * subframes_per_packet), dtype=np.float32), dummy_features.shape) 105 packet = np.flip(features, axis=-2) 106 packets.append(packet) 107 108 return packets