struct mp4; /* opaque */
-void mp4_set_sample_position(struct mp4 *f, int32_t track, int32_t sample);
+int mp4_set_sample_position(struct mp4 *f, uint32_t track, int32_t sample);
int32_t mp4_get_total_tracks(const struct mp4 *f);
bool mp4_is_audio_track(const struct mp4 *f, int32_t track);
struct mp4 *mp4_open_read(const struct mp4_callback *cb);