akkartik.name
Template repo for tiny cross-platform apps that can be modified on phone, tablet or computer.
1local wav = {
2 --[[
3 Writes audio file in WAVE format with PCM integer samples.
4
5 Function 'create_context' requires a filename and returns a table with the
6 following methods:
7 - init(channels_number, sample_rate, bits_per_sample)
8 - write_samples_interlaced(samples)
9 - finish()
10
11 (WAVE format: https://ccrma.stanford.edu/courses/422/projects/WaveFormat/)
12 ]]
13 --[[
14 Copyright © 2014, Christoph "Youka" Spanknebel
15 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
16 The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
18 ]]
19 create_context = function(filename)
20 -- Check function parameters
21 if type(filename) ~= "string" then
22 error("invalid function parameter, expected string filename", 2)
23 end
24 local absolute_path = love.filesystem.getSaveDirectory()..'/'..filename
25 -- ensure directory exists
26 love.filesystem.write(absolute_path, '')
27 -- Audio file handle
28 local file = io.open(absolute_path, "wb")
29 if not file then
30 error(string.format("couldn't open file %q", filename), 2)
31 end
32 -- Byte-string(unsigned integer,little endian)<-Lua-number converter
33 local function ntob(n, len)
34 local n, bytes = math.max(math.floor(n), 0), {}
35 for i=1, len do
36 bytes[i] = n % 256
37 n = math.floor(n / 256)
38 end
39 return string.char(unpack(bytes))
40 end
41 -- Check for integer
42 local function isint(n)
43 return type(n) == "number" and n == math.floor(n)
44 end
45 -- Audio meta informations
46 local channels_number_private, bytes_per_sample
47 -- Return audio handler
48 return {
49 init = function(channels_number, sample_rate, bits_per_sample)
50 -- Check function parameters
51 if not isint(channels_number) or channels_number < 1 or
52 not isint(sample_rate) or sample_rate < 2 or
53 not (bits_per_sample == 8 or bits_per_sample == 16 or bits_per_sample == 24 or bits_per_sample == 32) then
54 error("valid channels number, sample rate and bits per sample expected", 2)
55 end
56 -- Write file type
57 file:write("RIFF????WAVE") -- file size to insert later
58 -- Write format chunk
59 file:write("fmt ",
60 ntob(16, 4),
61 ntob(1, 2),
62 ntob(channels_number, 2),
63 ntob(sample_rate, 4),
64 ntob(sample_rate * channels_number * (bits_per_sample / 8), 4),
65 ntob(channels_number * (bits_per_sample / 8), 2),
66 ntob(bits_per_sample, 2))
67 -- Write data chunk (so far)
68 file:write("data????") -- data size to insert later
69 -- Set format memory
70 channels_number_private, bytes_per_sample = channels_number, bits_per_sample / 8
71 end,
72 write_samples_interlaced = function(samples)
73 -- Check function parameters
74 if type(samples) ~= "table" then
75 error("samples table expected", 2)
76 end
77 local samples_n = #samples
78 if samples_n == 0 or samples_n % channels_number_private ~= 0 then
79 error("valid number of samples expected (multiple of channels)", 2)
80 -- Already finished?
81 elseif not file then
82 error("already finished", 2)
83 -- Already initialized?
84 elseif file:seek() == 0 then
85 error("initialize before writing samples", 2)
86 end
87 -- All samples are numbers?
88 for i=1, samples_n do
89 if type(samples[i]) ~= "number" then
90 error("samples have to be numbers", 2)
91 end
92 end
93 -- Write samples to file
94 local sample
95 if bytes_per_sample == 1 then
96 for i=1, samples_n do
97 sample = samples[i]
98 file:write(ntob(sample < 0 and sample + 256 or sample, 1))
99 end
100 elseif bytes_per_sample == 2 then
101 for i=1, samples_n do
102 sample = samples[i]
103 file:write(ntob(sample < 0 and sample + 65536 or sample, 2))
104 end
105 elseif bytes_per_sample == 3 then
106 for i=1, samples_n do
107 sample = samples[i]
108 file:write(ntob(sample < 0 and sample + 16777216 or sample, 3))
109 end
110 else -- if bytes_per_sample == 4 then
111 for i=1, samples_n do
112 sample = samples[i]
113 file:write(ntob(sample < 0 and sample + 4294967296 or sample, 4))
114 end
115 end
116 end,
117 finish = function()
118 -- Already finished?
119 if not file then
120 error("already finished", 2)
121 -- Already initialized?
122 elseif file:seek() == 0 then
123 error("initialize before finishing", 2)
124 end
125 -- Get file size
126 local file_size = file:seek()
127 -- Save file size
128 file:seek("set", 4)
129 file:write(ntob(file_size - 8, 4))
130 -- Save data size
131 file:seek("set", 40)
132 file:write(ntob(file_size - 44, 4))
133 -- Finalize file for secure reading
134 file:close()
135 file = nil
136 end
137 }
138 end,
139}
140
141function save_wav(filename, sounddata)
142 -- credit to Intas and zorg on the LÖVE forum <3
143 -- https://love2d.org/forums/viewtopic.php?t=86173
144 local samples = {}
145 for i = 0, sounddata:getSampleCount() - 1 do
146 local sample = sounddata:getSample(i)
147 local n
148 local to16bit = sample * 32767
149 if (to16bit > 0) then
150 n = math.floor(math.min(to16bit, 32767))
151 else
152 n = math.floor(math.max(to16bit, -32768))
153 end
154 table.insert(samples, n)
155 end
156 local w = wav.create_context(filename, "w")
157 w.init(sounddata:getChannelCount(), sounddata:getSampleRate(), sounddata:getBitDepth())
158 w.write_samples_interlaced(samples)
159 w.finish()
160end