uint32_t mp4ff_get_sample_rate(const struct mp4ff *f, int32_t track);
uint32_t mp4ff_get_channel_count(const struct mp4ff * f, int32_t track);
int32_t mp4ff_num_samples(const struct mp4ff *f, int track);
+uint64_t mp4ff_get_duration(const struct mp4ff *f, int32_t track);
struct mp4ff *mp4ff_open_read_metaonly(struct mp4ff_callback *f);
int mp4ff_meta_get_by_index(const struct mp4ff *f, unsigned int index,