-int32_t mp4_get_sample_size(const struct mp4 *f, int track, int sample);
-uint32_t mp4_get_sample_rate(const struct mp4 *f, int32_t track);
-uint32_t mp4_get_channel_count(const struct mp4 * f, int32_t track);
-int32_t mp4_num_samples(const struct mp4 *f, int track);
-uint64_t mp4_get_duration(const struct mp4 *f, int32_t track);
-struct mp4 *mp4_open_meta(const struct mp4_callback *cb);
-
-int mp4_meta_get_by_index(const struct mp4 *f, unsigned int index,
- char **item, char **value);
-int32_t mp4_meta_update(const struct mp4_callback *cb,
- const struct mp4_metadata *data);
-
-int mp4_meta_get_num_items(const struct mp4 *f);
+int32_t mp4_get_sample_size(const struct mp4 *f, int sample);
+uint32_t mp4_get_sample_rate(const struct mp4 *f);
+uint32_t mp4_get_channel_count(const struct mp4 * f);
+int32_t mp4_num_samples(const struct mp4 *f);
+uint64_t mp4_get_duration(const struct mp4 *f);
+int mp4_open_meta(const struct mp4_callback *cb, struct mp4 **result);
+struct mp4_metadata *mp4_get_meta(struct mp4 *f);
+int32_t mp4_meta_update(struct mp4 *f);