captioner.c

/**********************************************************************************************/
/* The MIT License                                                                            */
/*                                                                                            */
/* Copyright 2016-2017 Twitch Interactive, Inc. or its affiliates. All Rights Reserved.       */
/*                                                                                            */
/* 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:                                   */
/*                                                                                            */
/* The above copyright notice and this permission notice shall be included in                 */
/* all copies or substantial portions of the Software.                                        */
/*                                                                                            */
/* 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.                                                                              */
/**********************************************************************************************/
#include "caption.h"
#include "flv.h"
#include <errno.h>
#include <fcntl.h>
#include <linux/input.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

char charcode[] = {
    0, 0, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '=', 0, 0,
    'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O', 'P', '[', ']', '\n', 0, 'A', 'S',
    'D', 'F', 'G', 'H', 'J', 'K', 'L', ';', '\'', '`', 0, '\\', 'Z', 'X', 'C', 'V',
    'B', 'N', 'M', ',', '.', '/', 0, '*', 0, ' ', 0, 0, 0, 0, 0, 0,
};

int data_ready(int fd)
{
    fd_set set;
    struct timeval timeout = { 0, 0 };
    FD_ZERO(&set);
    FD_SET(fd, &set);
    int cnt = select(fd + 1, &set, 0, 0, &timeout);
    FD_ZERO(&set);
    return (0 < cnt);
}

#define MAX_CAP_LENGTH (SCREEN_ROWS * SCREEN_COLS)
int main(int argc, char** argv)
{
    int fd;
    ssize_t n;
    flvtag_t tag;
    struct input_event ev;
    int has_audio, has_video;
    const char* dev = argv[1];
    char text[MAX_CAP_LENGTH + 1];
    memset(text, 0, MAX_CAP_LENGTH + 1);

    FILE* flv = flv_open_read("-");
    FILE* out = flv_open_write("-");
    fd = open(dev, O_RDONLY);

    if (fd == -1) {
        fprintf(stderr, "Cannot open %s: %s.\n", dev, strerror(errno));
        return EXIT_FAILURE;
    }

    if (!flv_read_header(flv, &has_audio, &has_video)) {
        fprintf(stderr, "%s is not an flv file\n", argv[1]);
        return EXIT_FAILURE;
    }

    if (!flv_write_header(out, has_audio, has_video)) {
        return EXIT_FAILURE;
    }

    flvtag_init(&tag);

    while (flv_read_tag(flv, &tag)) {
        if (flvtag_avcpackettype_nalu == flvtag_avcpackettype(&tag)) {
            if (data_ready(fd)) {
                n = read(fd, &ev, sizeof ev);

                if (n == (ssize_t)-1) {
                    if (errno == EINTR) {
                        continue;
                    } else {
                        break;
                    }
                } else if (n != sizeof ev) {
                    errno = EIO;
                    break;
                }

                int len = strlen(text);
                char c = (EV_KEY == ev.type && 1 == ev.value && ev.code < 64) ? charcode[ev.code] : 0;

                if (0 < len && '\n' == c) {
                    fprintf(stderr, "='%s'\n", text);
                    flvtag_addcaption(&tag, text);
                    memset(text, 0, MAX_CAP_LENGTH + 1);
                } else if (0 != c && len < MAX_CAP_LENGTH) {
                    text[len] = c;
                }
            }
        }

        flv_write_tag(out, &tag);
    }

    return EXIT_SUCCESS;
}