example_encode.c

 
/*
 * compile with
 *  gcc -o ltc-encoder example_encode.c -lltc -lm
 *
 * from the source-folder this can be compiled after building libltc:
 *  gcc -o ltc-encoder example_encode.c ../src/.libs/libltc.a -lm -I../src
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <ltc.h>
 
#ifdef _WIN32
#include <fcntl.h> // for _fmode
#endif
 
/* define "USE_LOCAL_BUFFER" to
 * use a local buffer instead of a pointer to
 * libltc's internal buffer
 */
//#define USE_LOCAL_BUFFER
 
int main(int argc, char **argv) {
        FILE* file;
        double length = 2; // in seconds
        double fps = 25;
        double sample_rate = 48000;
        char *filename;
 
        int vframe_cnt;
        int vframe_last;
 
        int total = 0;
        ltcsnd_sample_t *buf;
 
        LTCEncoder *encoder;
        SMPTETimecode st;
 
        /* start encoding at this timecode */
        const char timezone[6] = "+0100";
        strcpy(st.timezone, timezone);
        st.years =  8;
        st.months = 12;
        st.days =   31;
 
        st.hours = 23;
        st.mins = 59;
        st.secs = 59;
        st.frame = 0;
 
        /* parse commandline args */
        if (argc > 1) {
                filename = argv[1];
                if (argc > 2) {
                        sample_rate = atof(argv[2]);
                }
                if (argc > 3) {
                        fps = atof(argv[3]);
                }
                if (argc > 4) {
                        length = atof(argv[4]);
                }
        } else {
                printf("ltc-encoder - test/example application to encode LTC to a file\n\n");
                printf("Usage: ltc-encoder <filename> [sample rate [frame rate [duration in s]]]\n\n");
                printf("default-values:\n");
                printf(" sample rate: 48000.0 [SPS], frame rate: 25.0 [fps], duration: 2.0 [sec]\n");
                printf("Report bugs to Robin Gareus <robin@gareus.org>\n");
                return 1;
        }
 
#ifdef _WIN32
        // see https://msdn.microsoft.com/en-us/library/ktss1a9b.aspx and
        // https://github.com/x42/libltc/issues/18
        _set_fmode(_O_BINARY);
#endif
 
        /* open output file */
        file = fopen(filename, "wb");
        if (!file) {
                fprintf(stderr, "Error: can not open file '%s' for writing.\n", filename);
                return 1;
        }
 
        /* prepare encoder */
        encoder = ltc_encoder_create(sample_rate, fps,
                        fps==25?LTC_TV_625_50:LTC_TV_525_60, LTC_USE_DATE);
        ltc_encoder_set_timecode(encoder, &st);
 
#ifdef USE_LOCAL_BUFFER
        buf = calloc(ltc_encoder_get_buffersize(encoder), sizeof(ltcsnd_sample_t));
        if (!buf) {
                return -1;
        }
#endif
 
        /* ready to go, print some info first */
 
        printf("sample rate: %.2f\n", sample_rate);
        printf("frames/sec: %.2f\n", fps);
        printf("secs to write: %.2f\n", length);
        printf("sample format: 8bit unsigned mono\n");
 
        vframe_cnt = 0;
        vframe_last = length * fps;
 
        while (vframe_cnt++ < vframe_last) {
#if 1 /* encode and write each of the 80 LTC frame bits (10 bytes) */
                int byte_cnt;
                for (byte_cnt = 0 ; byte_cnt < 10 ; byte_cnt++) {
                        ltc_encoder_encode_byte(encoder, byte_cnt, 1.0);
 
#ifdef USE_LOCAL_BUFFER
                        int len = ltc_encoder_copy_buffer(encoder, buf);
#else
                        int len = ltc_encoder_get_bufferptr (encoder, &buf, 1);
#endif
                        if (len > 0) {
                                fwrite(buf, sizeof(ltcsnd_sample_t), len, file);
                                total+=len;
                        }
                }
#else /* encode a complete LTC frame in one step */
                ltc_encoder_encode_frame(encoder);
 
#ifdef USE_LOCAL_BUFFER
                int len = ltc_encoder_copy_buffer(encoder, buf);
#else
                int len = ltc_encoder_get_bufferptr(encoder, &buf, 1);
#endif
 
                if (len > 0) {
                        fwrite(buf, sizeof(ltcsnd_sample_t), len, file);
                        total+=len;
                }
#endif
 
                ltc_encoder_inc_timecode(encoder);
        }
        fclose(file);
        ltc_encoder_free(encoder);
 
        printf("Done: wrote %d samples to '%s'\n", total, filename);
 
#ifdef USE_LOCAL_BUFFER
        free(buf);
#endif
 
        return 0;
}