├── .gitignore ├── LICENSE.md ├── README.md ├── face.png ├── spectrophoto.c └── stb_image.h /.gitignore: -------------------------------------------------------------------------------- 1 | out.pcm 2 | spectrogram.png 3 | spectrophoto 4 | -------------------------------------------------------------------------------- /LICENSE.md: -------------------------------------------------------------------------------- 1 | The MIT License (MIT) 2 | 3 | Copyright (c) 2015 Kyle Swanson 4 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy 6 | of this software and associated documentation files (the "Software"), to deal 7 | in the Software without restriction, including without limitation the rights 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 | copies of the Software, and to permit persons to whom the Software is 10 | furnished to do so, subject to the following conditions: 11 | 12 | The above copyright notice and this permission notice shall be included in all 13 | copies or substantial portions of the Software. 14 | 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 | SOFTWARE. 22 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # spectrophoto 2 | Turns an image into an audio file. Image is visible on the spectrogram. 3 | 4 | ## Building 5 | ```bash 6 | git clone https://github.com/kylophone/spectrophoto 7 | cd spectrophoto 8 | gcc ./spectrophoto.c -o spectrophoto -std=c99 -lm -O3 -Wall 9 | ``` 10 | ## Usage 11 | ``` 12 | spectrophoto in.jpg out.pcm 10 13 | ``` 14 | ## Output 15 | This will generate a 48k/32-bit floating point raw PCM file. You can listen to it with SoX like this: 16 | 17 | `play -c 1 -r 48000 -b 32 -e float -t raw out.pcm` 18 | 19 | Generating a spectrogram with SoX looks like this: 20 | 21 | `sox -c 1 -r 48000 -b 32 -e float -t raw out.pcm -n spectrogram` 22 | -------------------------------------------------------------------------------- /face.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/kylophone/spectrophoto/de54397502991b824a59c4ab1e4558362a9a0764/face.png -------------------------------------------------------------------------------- /spectrophoto.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | 5 | #define STB_IMAGE_IMPLEMENTATION 6 | #include "stb_image.h" 7 | 8 | #ifndef M_PI 9 | #define M_PI 3.14159265358979323846 10 | #endif 11 | 12 | #define SAMPLE_RATE 48000 13 | 14 | void column_to_PCM(float *buf, float *column, int nb_samples, int height, float **sin_lut) 15 | { 16 | float sample = 0.; 17 | 18 | for (int i = 0; i < nb_samples; i++) { 19 | for (int j = 0; j < height; j++) { 20 | sample += (column[j] * sin_lut[j][i]) / height; 21 | } 22 | sample *= .90; 23 | buf[i] = sample; 24 | } 25 | } 26 | 27 | int get_point_index(int i, int j, int x, int n) 28 | { 29 | return (j * (x * n)) + i * n; 30 | } 31 | 32 | float get_pixel_intensity(unsigned char *img, int n) 33 | { 34 | int RGB_sum = 0; 35 | for (int i = 0; i < n; i++) { 36 | RGB_sum += img[i]; 37 | } 38 | float intensity = ((float) RGB_sum / n) / 255; 39 | return intensity; 40 | } 41 | 42 | int main(int argc, char **argv) 43 | { 44 | if (argc != 4) { 45 | fprintf(stderr, "Usage: %s \n", argv[0]); 46 | return 1; 47 | } 48 | 49 | int x,y,n; 50 | const char *input_file = argv[1]; 51 | unsigned char *img = stbi_load(input_file, &x, &y, &n, 1); 52 | if (!img) { 53 | fprintf(stderr, "Couldn't load image: %s\n", input_file); 54 | return 1; 55 | } 56 | 57 | int duration = atoi(argv[3]); 58 | int nb_samples = (duration * SAMPLE_RATE) / x; 59 | if (nb_samples <= 0) { 60 | fprintf(stderr, "Duration is too low: %d\n", duration); 61 | return 1; 62 | } 63 | 64 | const char *output_file = argv[2]; 65 | FILE *pcm = fopen(output_file, "wb"); 66 | if (!pcm) { 67 | fprintf(stderr, "Couldn't open file: %s\n", output_file); 68 | return 1; 69 | } 70 | 71 | float *column = malloc(sizeof(float) * y); 72 | if (!column) { 73 | fprintf(stderr, "Couldn't allocate buffer.\n"); 74 | return 1; 75 | } 76 | 77 | float *buf = malloc(sizeof(float) * nb_samples); 78 | if (!buf) { 79 | fprintf(stderr, "Couldn't allocate buffer.\n"); 80 | return 1; 81 | } 82 | 83 | float **sin_lut = malloc(sizeof(float*) * y); 84 | if (!sin_lut) { 85 | fprintf(stderr, "Couldn't allocate buffer.\n"); 86 | return 1; 87 | } 88 | 89 | for (int i = 0; i < y; i++) { 90 | sin_lut[i] = malloc(sizeof(float) * nb_samples); 91 | if (!sin_lut[i]) { 92 | fprintf(stderr, "Couldn't allocate buffer.\n"); 93 | return 1; 94 | } 95 | } 96 | 97 | float nyquist = (float) SAMPLE_RATE / 2; 98 | float hz_step = nyquist / y; 99 | for (int i = 0; i < y; i++) { 100 | for (int j = 0; j < nb_samples; j++) { 101 | float freq = nyquist - (hz_step * i); 102 | float env = sin(2 * M_PI * ((float) j / nb_samples)); 103 | sin_lut[i][j] = env * sin(2 * M_PI * freq * ((float) j / SAMPLE_RATE)); 104 | } 105 | } 106 | 107 | for (int i = 0; i < x; i++) { 108 | for (int j = 0; j < y; j++) { 109 | int index = get_point_index(i, j, x, 1); 110 | float intensity = get_pixel_intensity(&img[index], 1); 111 | column[j] = intensity; 112 | } 113 | column_to_PCM(buf, column, nb_samples, y, sin_lut); 114 | fwrite(buf, sizeof(float) * nb_samples, 1, pcm); 115 | } 116 | 117 | for (int i = 0; i < y; i++) 118 | free(sin_lut[i]); 119 | free(sin_lut); 120 | 121 | free(buf); 122 | free(column); 123 | stbi_image_free(img); 124 | 125 | fclose(pcm); 126 | return 0; 127 | } 128 | --------------------------------------------------------------------------------