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#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>
#define MIN(a, b) ((a < b)? a : b)
#define FRAMES_PER_SEC 75
#define BUFFER_SIZE 1024*1024 /* Meh, good enough */
/* Grabs a 'mm:ss:ff' stamp from stdin */
double get_sec()
{
int mm = 0;
int ss = 0;
int ff = 0;
int items = fscanf(stdin, "%d:%d:%d\n", &mm, &ss, &ff);
/* EOF means this is the last track; return invalid time */
if (items == EOF)
return -1;
if (items != 3) {
fprintf(stderr, "Timestamp malformed\n");
exit(-1);
}
return (mm*60 + ss + ((double)ff)/FRAMES_PER_SEC);
}
/* Constructs an output filename in the specified buffer based on the given format and track number
* Main purpose is to catch buffer overflow with snprintf
*/
int construct_out_name(char *buffer, size_t buffer_size, char* name, unsigned int track)
{
if (snprintf(buffer, buffer_size, "%03d%s", track, name) >= buffer_size - 1) {
fprintf(stderr, "Filename too large for buffer (max %zd)\n", buffer_size);
return -1;
}
return 0;
}
/* Displays the help/syntax message and dies
* Does what it says on the tin
*/
void die_help()
{
fprintf(stderr,
"\n"
"Options: \n"
" -r bitrate_Hz\n"
" -c channel_count\n"
" -i input_file\n"
" -s size of a single channel's sample (bytes)\n"
" -n output file name (prepended with track number)\n"
);
exit(1);
}
int main(int argc, char **argv)
{
/* File handles */
FILE *fin = NULL;
FILE *fout = NULL;
/* Command line options */
char *name = NULL;
char *in_fname = NULL;
int channels = 0;
int rate = 0;
int sample_size = 0;
/* Misc */
char opt = '\0';
char out_fname[1024]; /* That should do it. Note: overflow IS caught */
int track = 0;
int items = 0;
unsigned long i = 0;
char buffer[BUFFER_SIZE];
/* Boundaries */
double start_sec = 0;
double finish_sec = 0;
unsigned long start_sample = 0;
unsigned long finish_sample = 0;
while ((opt = getopt(argc, argv, "r:c:i:s:n:")) != -1) {
switch (opt) {
case 'r': rate = atoi(optarg); break;
case 'c': channels = atoi(optarg); break;
case 's': sample_size = atoi(optarg); break;
case 'i': in_fname = optarg; break;
case 'n': name = optarg; break;
case '?':
default:
die_help();
}
}
if (channels <= 0 ||
rate <= 0 ||
sample_size <= 0) {
fprintf(stderr, "ERROR: Channel count, bitrate and sample size must all be present and positive\n");
die_help();
}
if (in_fname == NULL ||
name == NULL) {
fprintf(stderr, "ERROR: Input filename and output name must be present\n");
die_help();
}
/* Open it up */
if ((fin = fopen(in_fname, "r")) == NULL) {
fprintf(stderr,"Failed to open '%s': ", in_fname);
perror("fopen");
return -1;
}
track = 0;
start_sec = get_sec();
/* Start time can't be unspecified, only finish */
if (start_sec < 0) {
fprintf(stderr, "ERROR: At least one start timestamp must be specified\n");
return -1;
}
/* finish_sample equals ULONG_MAX if a run was to EOF (the last track) */
while (finish_sample != ULONG_MAX) {
track++;
if (construct_out_name(out_fname, sizeof(out_fname), name, track) < 0) {
fclose(fin);
return 1;
}
finish_sec = get_sec();
printf("%s starts %f s, finishes ", out_fname, start_sec);
if (finish_sec < 0)
printf("EOF\n");
else
printf("%f s\n", finish_sec);
/* Open output file */
if ((fout = fopen(out_fname, "w")) == NULL) {
fprintf(stderr,"Failed to open '%s': ", out_fname);
perror("fopen");
fclose(fin);
return -1;
}
start_sample = start_sec * rate * channels;
finish_sample = finish_sec * rate * channels;
if (start_sample > finish_sample) {
fprintf(stderr, "ERROR: Finish time can't be before start time, skipping %s\n", out_fname);
continue;
}
/* Run to "infinity" if no finish time set.
* Of course, will actually run to EOF assuming file's small enough
* FIXME assumes last track has less than ULONG_MAX samples */
if (finish_sec == -1)
finish_sample = ULONG_MAX;
for (i = start_sample; i < finish_sample; i += items) {
items = fread(buffer,
sample_size,
MIN(sizeof(buffer)/sample_size, (finish_sample - i)),
fin);
if (items == 0) {
if (feof(fin))
break;
if (ferror(fin)) {
perror("fread");
break;
}
}
if (fwrite(buffer, sample_size, items, fout) != items) {
fprintf(stderr, "Write to %s failed: ", out_fname);
perror("fwrite");
break;
}
}
fclose(fout);
start_sec = finish_sec;
}
fclose(fin);
return 0;
}
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