JNIEXPORT jint JNICALL Java_com_axelby_mp3decoders_MPG123_getSeekFrameOffset
(JNIEnv *env, jclass c, jlong mp3file, jfloat seconds)
{
MP3File *mp3 = (MP3File *)mp3file;
mpg123_handle *mh = mp3->handle;
size_t fill;
off_t step;
off_t* offsets;
mpg123_index(mh, &offsets, &step, &fill);
int target_frame = (int) (seconds / mp3->secs_per_frame); // the frame number to seek to
int target_index = target_frame / step; // the closest index to the target frame
// say so if there aren't enough entries in the index
if (target_index >= fill)
return -1;
return offsets[target_index];
}
static int print_index(mpg123_handle *mh)
{
int err;
size_t c, fill;
off_t *index;
off_t step;
err = mpg123_index(mh, &index, &step, &fill);
if(err == MPG123_ERR)
{
fprintf(stderr, "Error accessing frame index: %s\n", mpg123_strerror(mh));
return err;
}
for(c=0; c < fill;++c)
fprintf(stderr, "[%lu] %lu: %li (+%li)\n",
(unsigned long) c,
(unsigned long) (c*step),
(long) index[c],
(long) (c ? index[c]-index[c-1] : 0));
return MPG123_OK;
}