int mp4_open_read(const struct mp4_callback *cb, struct mp4 **result);
void mp4_close(struct mp4 *f);
int mp4_get_sample_size(const struct mp4 *f, uint32_t sample, uint32_t *result);
int mp4_open_read(const struct mp4_callback *cb, struct mp4 **result);
void mp4_close(struct mp4 *f);
int mp4_get_sample_size(const struct mp4 *f, uint32_t sample, uint32_t *result);