+/** \file mp4.h Public API of the mp4 parser. */
+
+/**
+ * Callbacks provided by the user of the mp4 parsing API.
+ *
+ * A pointer to this structure is passed to the two public open functions. If
+ * the file is opened in read-only mode, the ->write() and ->truncate() methods
+ * won't be called and may thus be NULL. The ->read() and ->seek() methods
+ * must be supplied for either open type.
+ *
+ * All methods are supposed to work like their corresponding system calls.
+ * That is, they should return non-negative for success and -1 on failure. In
+ * the error case errno is expected to be set accordingly.
+ *
+ * \sa \ref mp4_open(), \ref mp4_open_meta().
+ */
struct mp4_callback {
+ /** This pointer is propagated to each call of all methods. */
+ void *user_data;
+ /**
+ * This should return the number of bytes read on success. Short reads
+ * are OK: the function may return less than length.
+ */
ssize_t (*read)(void *user_data, void *buffer, size_t length);
- ssize_t (*write)(void *user_data, void *buffer, size_t count);
+ /**
+ * This method is assumed to succeed. The implementation should simply
+ * abort on errors. Note that offsets beyond EOF must not be regarded
+ * as invalid arguments.
+ */
off_t (*seek)(void *user_data, off_t offset, int whence);
+ /**
+ * Like the write() system call, this should return the number of bytes
+ * written. Short writes are OK: the function may return less than
+ * count.
+ */
+ ssize_t (*write)(void *user_data, void *buffer, size_t count);
+ /**
+ * Unlike the truncate system call, this function does not receive an
+ * offset. The method is expected to truncate the file to the offset
+ * given by the current file position instead.
+ */
int (*truncate)(void *user_data);
- void *user_data;
};
+/** Specifies one metadata tag. Both fields are 0-terminated strings. */
struct mp4_tag {
- char *item;
- char *value;
- uint32_t len;
+ /** The item name: "artist", "title", "album", "comment", or "date". */
+ char *item;
+ /** An arbitrary string value. */
+ char *value;
};
+/**
+ * An array of name/value pairs.
+ *
+ * This structure is initialized when the mp4 file is opened in either mode.
+ * If the file contains metadata items other than the standard five, those
+ * non-standard items are not included in the array. After a successful open, a
+ * pointer to the metadata structure can be obtained via \ref mp4_get_meta().
+ */
struct mp4_metadata {
- struct mp4_tag *tags;
- uint32_t count;
+ /** It's OK to change this, for example by calling realloc(). */
+ struct mp4_tag *tags;
+ /** The number of entries of the array. */
+ unsigned count;
};
-struct mp4; /* opaque */
+/**
+ * The mp4 file handle.
+ *
+ * A pointer to this opaque structure is returned by the two open functions.
+ * All other functions of the mp4 API receive a pointer of this type.
+ */
+struct mp4;
-int mp4_set_sample_position(struct mp4 *f, int32_t sample);
-int mp4_open_read(const struct mp4_callback *cb, struct mp4 **result);
+int mp4_set_sample_position(struct mp4 *f, uint32_t sample);
+int mp4_open(const struct mp4_callback *cb, struct mp4 **result);
void mp4_close(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);
+int mp4_get_sample_size(const struct mp4 *f, uint32_t sample, uint32_t *result);
+uint16_t mp4_get_sample_rate(const struct mp4 *f);
+uint16_t mp4_get_channel_count(const struct mp4 *f);
+uint32_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);
-int mp4_meta_update(struct mp4 *f);
+int mp4_update_meta(struct mp4 *f);
char *mp4_get_tag_value(const struct mp4 *f, const char *item);