libmtp: The track management API.

libmtp 1.1.21

Functions
The track management API.

## Functions
LIBMTP_track_t * | LIBMTP_new_track_t (void)
void | LIBMTP_destroy_track_t (LIBMTP_track_t *)
LIBMTP_track_t * | LIBMTP_Get_Tracklisting (LIBMTP_mtpdevice_t *)
LIBMTP_track_t * | LIBMTP_Get_Tracklisting_With_Callback (LIBMTP_mtpdevice_t *, LIBMTP_progressfunc_t const, void const *const)
LIBMTP_track_t * | LIBMTP_Get_Tracklisting_With_Callback_For_Storage (LIBMTP_mtpdevice_t *, uint32_t const, LIBMTP_progressfunc_t const, void const *const)
LIBMTP_track_t * | LIBMTP_Get_Trackmetadata (LIBMTP_mtpdevice_t *, uint32_t const)
int | LIBMTP_Get_Track_To_File (LIBMTP_mtpdevice_t *, uint32_t, char const *const, LIBMTP_progressfunc_t const, void const *const)
int | LIBMTP_Get_Track_To_File_Descriptor (LIBMTP_mtpdevice_t *, uint32_t const, int const, LIBMTP_progressfunc_t const, void const *const)
int | LIBMTP_Get_Track_To_Handler (LIBMTP_mtpdevice_t *, uint32_t const, MTPDataPutFunc, void *, LIBMTP_progressfunc_t const, void const *const)
int | LIBMTP_Send_Track_From_File (LIBMTP_mtpdevice_t *, char const *const, LIBMTP_track_t *const, LIBMTP_progressfunc_t const, void const *const)
int | LIBMTP_Send_Track_From_File_Descriptor (LIBMTP_mtpdevice_t *, int const, LIBMTP_track_t *const, LIBMTP_progressfunc_t const, void const *const)
int | LIBMTP_Send_Track_From_Handler (LIBMTP_mtpdevice_t *, MTPDataGetFunc, void *, LIBMTP_track_t *const, LIBMTP_progressfunc_t const, void const *const)
int | LIBMTP_Update_Track_Metadata (LIBMTP_mtpdevice_t *, LIBMTP_track_t const *const)
int | LIBMTP_Track_Exists (LIBMTP_mtpdevice_t *, uint32_t const)
int | LIBMTP_Set_Track_Name (LIBMTP_mtpdevice_t *, LIBMTP_track_t *, const char *)

## Detailed Description

## Function Documentation

## ◆ LIBMTP_destroy_track_t()

void LIBMTP_destroy_track_t | ( | LIBMTP_track_t * | track | ) |

This destroys a track metadata structure and deallocates the memory used by it, including any strings. Never use a track metadata structure again after calling this function on it.

Parameters

  track | the track metadata to destroy.

See also
  LIBMTP_new_track_t()

References LIBMTP_track_struct::album, LIBMTP_track_struct::artist, LIBMTP_track_struct::composer, LIBMTP_track_struct::date, LIBMTP_track_struct::filename, LIBMTP_track_struct::genre, and LIBMTP_track_struct::title.

Referenced by LIBMTP_Get_Tracklisting_With_Callback_For_Storage(), and LIBMTP_Get_Trackmetadata().

## ◆ LIBMTP_Get_Track_To_File()

int LIBMTP_Get_Track_To_File | ( | LIBMTP_mtpdevice_t * | device,
|  | uint32_t const | id,
|  | char const *const | path,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This gets a track off the device to a file identified by a filename. This is actually just a wrapper for the `LIBMTP_Get_Track_To_File()` function.

Parameters

  device | a pointer to the device to get the track from.
  id | the track ID of the track to retrieve.
  path | a filename to use for the retrieved track.
  callback | a progress indicator function or NULL to ignore.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  0 if the transfer was successful, any other value means failure.

See also
  LIBMTP_Get_Track_To_File_Descriptor()

References LIBMTP_Get_File_To_File().

## ◆ LIBMTP_Get_Track_To_File_Descriptor()

int LIBMTP_Get_Track_To_File_Descriptor | ( | LIBMTP_mtpdevice_t * | device,
|  | uint32_t const | id,
|  | int const | fd,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This gets a track off the device to a file identified by a file descriptor. This is actually just a wrapper for the `LIBMTP_Get_File_To_File_Descriptor()` function.

Parameters

  device | a pointer to the device to get the track from.
  id | the track ID of the track to retrieve.
  fd | a file descriptor to write the track to.
  callback | a progress indicator function or NULL to ignore.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  0 if the transfer was successful, any other value means failure.

See also
  LIBMTP_Get_Track_To_File()

References LIBMTP_Get_File_To_File_Descriptor().

## ◆ LIBMTP_Get_Track_To_Handler()

int LIBMTP_Get_Track_To_Handler | ( | LIBMTP_mtpdevice_t * | device,
|  | uint32_t const | id,
|  | MTPDataPutFunc | put_func,
|  | void * | priv,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This gets a track off the device to a handler function. This is actually just a wrapper for the `LIBMTP_Get_File_To_Handler()` function.

Parameters

  device | a pointer to the device to get the track from.
  id | the track ID of the track to retrieve.
  put_func | the function to call when we have data.
  priv | the user-defined pointer that is passed to `put_func`.
  callback | a progress indicator function or NULL to ignore.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  0 if the transfer was successful, any other value means failure.

References LIBMTP_Get_File_To_Handler().

## ◆ LIBMTP_Get_Tracklisting()

LIBMTP_track_t * LIBMTP_Get_Tracklisting | ( | LIBMTP_mtpdevice_t * | device | ) |

THIS FUNCTION IS DEPRECATED. PLEASE UPDATE YOUR CODE IN ORDER NOT TO USE IT.

See also
  LIBMTP_Get_Tracklisting_With_Callback()

References LIBMTP_Get_Tracklisting_With_Callback().

## ◆ LIBMTP_Get_Tracklisting_With_Callback()

LIBMTP_track_t * LIBMTP_Get_Tracklisting_With_Callback | ( | LIBMTP_mtpdevice_t * | device,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This returns a long list of all tracks available on the current MTP device. Tracks include multimedia objects, both music tracks and video tracks. Typical usage:

    LIBMTP_track_t *tracklist;

    tracklist = LIBMTP_Get_Tracklisting_With_Callback(device, callback, data);
    while (tracklist != NULL) {
      LIBMTP_track_t *tmp;

      // Do something on each element in the list here...
      tmp = tracklist;
      tracklist = tracklist->next;
      LIBMTP_destroy_track_t(tmp);
    }

If you want to group your track listing by storage (per storage unit) or arrange tracks into folders, you must dereference the `storage_id` and/or `parent_id` field of the returned `LIBMTP_track_t` struct. To arrange by folders or files you typically have to create the proper trees by calls to `LIBMTP_Get_Storage()` and/or `LIBMTP_Get_Folder_List()` first.

Parameters

  device | a pointer to the device to get the track listing for.
  callback | a function to be called during the tracklisting retrieveal for displaying progress bars etc, or NULL if you don't want any callbacks.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  a list of tracks that can be followed using the `next` field of the `LIBMTP_track_t` data structure. Each of the metadata tags must be freed after use, and may contain only partial metadata information, i.e. one or several fields may be NULL or 0.

See also
  LIBMTP_Get_Trackmetadata()

References LIBMTP_Get_Tracklisting_With_Callback_For_Storage().

Referenced by LIBMTP_Get_Tracklisting().

## ◆ LIBMTP_Get_Tracklisting_With_Callback_For_Storage()

LIBMTP_track_t * LIBMTP_Get_Tracklisting_With_Callback_For_Storage | ( | LIBMTP_mtpdevice_t * | device,
|  | uint32_t const | storage_id,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This returns a long list of all tracks available on the current MTP device. Tracks include multimedia objects, both music tracks and video tracks. Typical usage:

    LIBMTP_track_t *tracklist;

    tracklist = LIBMTP_Get_Tracklisting_With_Callback_For_Storage(device, storage_id, callback, data);
    while (tracklist != NULL) {
      LIBMTP_track_t *tmp;

      // Do something on each element in the list here...
      tmp = tracklist;
      tracklist = tracklist->next;
      LIBMTP_destroy_track_t(tmp);
    }

If you want to group your track listing by storage (per storage unit) or arrange tracks into folders, you must dereference the `storage_id` and/or `parent_id` field of the returned `LIBMTP_track_t` struct. To arrange by folders or files you typically have to create the proper trees by calls to `LIBMTP_Get_Storage()` and/or `LIBMTP_Get_Folder_List()` first.

Parameters

  device | a pointer to the device to get the track listing for.
  storage_id | ID of device storage (if null, no filter)
  callback | a function to be called during the tracklisting retrieveal for displaying progress bars etc, or NULL if you don't want any callbacks.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  a list of tracks that can be followed using the `next` field of the `LIBMTP_track_t` data structure. Each of the metadata tags must be freed after use, and may contain only partial metadata information, i.e. one or several fields may be NULL or 0.

See also
  LIBMTP_Get_Trackmetadata()

References LIBMTP_track_struct::filename, LIBMTP_track_struct::filesize, LIBMTP_track_struct::filetype, LIBMTP_track_struct::item_id, LIBMTP_destroy_track_t(), LIBMTP_FILETYPE_IS_TRACK, LIBMTP_new_track_t(), LIBMTP_track_struct::modificationdate, LIBMTP_track_struct::next, LIBMTP_mtpdevice_struct::params, LIBMTP_track_struct::parent_id, LIBMTP_track_struct::storage_id, and LIBMTP_mtpdevice_struct::usbinfo.

Referenced by LIBMTP_Get_Tracklisting_With_Callback().

## ◆ LIBMTP_Get_Trackmetadata()

LIBMTP_track_t * LIBMTP_Get_Trackmetadata | ( | LIBMTP_mtpdevice_t * | device,
|  | uint32_t const | trackid )

This function retrieves the metadata for a single track off the device.

Do not call this function repeatedly! The track handles are linearly searched O(n) and the call may involve (slow) USB traffic, so use `LIBMTP_Get_Tracklisting()` and cache the tracks, preferably as an efficient data structure such as a hash list.

Parameters

  device | a pointer to the device to get the track metadata from.
  trackid | the object ID of the track that you want the metadata for.

Returns
  a track metadata entry on success or NULL on failure.

See also
  LIBMTP_Get_Tracklisting()

References LIBMTP_track_struct::filename, LIBMTP_track_struct::filesize, LIBMTP_track_struct::filetype, LIBMTP_track_struct::item_id, LIBMTP_destroy_track_t(), LIBMTP_FILETYPE_IS_TRACK, LIBMTP_new_track_t(), LIBMTP_track_struct::modificationdate, LIBMTP_mtpdevice_struct::params, LIBMTP_track_struct::parent_id, LIBMTP_track_struct::storage_id, and LIBMTP_mtpdevice_struct::usbinfo.

## ◆ LIBMTP_new_track_t()

LIBMTP_track_t * LIBMTP_new_track_t | ( | void |  | ) |

This creates a new track metadata structure and allocates memory for it. Notice that if you add strings to this structure they will be freed by the corresponding `LIBMTP_destroy_track_t` operation later, so be careful of using strdup() when assigning strings, e.g.:

    LIBMTP_track_t *track = LIBMTP_new_track_t();
    track->title = strdup(titlestr);
    ....
    LIBMTP_destroy_track_t(track);

Returns
  a pointer to the newly allocated metadata structure.

See also
  LIBMTP_destroy_track_t()

References LIBMTP_track_struct::item_id.

Referenced by LIBMTP_Get_Tracklisting_With_Callback_For_Storage(), and LIBMTP_Get_Trackmetadata().

## ◆ LIBMTP_Send_Track_From_File()

int LIBMTP_Send_Track_From_File | ( | LIBMTP_mtpdevice_t * | device,
|  | char const *const | path,
|  | LIBMTP_track_t *const | metadata,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This function sends a track from a local file to an MTP device. A filename and a set of metadata must be given as input.

Parameters

  device | a pointer to the device to send the track to.
  path | the filename of a local file which will be sent.
  metadata | a track metadata set to be written along with the file. After this call the field `metadata->item_id` will contain the new track ID. Other fields such as the `metadata->filename`, `metadata->parent_id` or `metadata->storage_id` may also change during this operation due to device restrictions, so do not rely on the contents of this struct to be preserved in any way. `metadata->parent_id` should be set to the parent (e.g. folder) to store this track in. Since some devices are a bit picky about where files are placed, a default folder will be chosen if libmtp has detected one for the current filetype and this parameter is set to 0. If this is 0 and no default folder can be found, the file will be stored in the root folder. `metadata->storage_id` should be set to the desired storage (e.g. memory card or whatever your device presents) to store this track in. Setting this to 0 will store the track on the primary storage.
  callback | a progress indicator function or NULL to ignore.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  0 if the transfer was successful, any other value means failure.

See also
  LIBMTP_Send_Track_From_File_Descriptor()
  LIBMTP_Send_File_From_File()
  LIBMTP_Delete_Object()

References LIBMTP_Send_Track_From_File_Descriptor().

## ◆ LIBMTP_Send_Track_From_File_Descriptor()

int LIBMTP_Send_Track_From_File_Descriptor | ( | LIBMTP_mtpdevice_t * | device,
|  | int const | fd,
|  | LIBMTP_track_t *const | metadata,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This function sends a track from a file descriptor to an MTP device. A filename and a set of metadata must be given as input.

Parameters

  device | a pointer to the device to send the track to.
  fd | the filedescriptor for a local file which will be sent.
  metadata | a track metadata set to be written along with the file. After this call the field `metadata->item_id` will contain the new track ID. Other fields such as the `metadata->filename`, `metadata->parent_id` or `metadata->storage_id` may also change during this operation due to device restrictions, so do not rely on the contents of this struct to be preserved in any way. `metadata->parent_id` should be set to the parent (e.g. folder) to store this track in. Since some devices are a bit picky about where files are placed, a default folder will be chosen if libmtp has detected one for the current filetype and this parameter is set to 0. If this is 0 and no default folder can be found, the file will be stored in the root folder. `metadata->storage_id` should be set to the desired storage (e.g. memory card or whatever your device presents) to store this track in. Setting this to 0 will store the track on the primary storage.
  callback | a progress indicator function or NULL to ignore.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  0 if the transfer was successful, any other value means failure.

See also
  LIBMTP_Send_Track_From_File()
  LIBMTP_Delete_Object()

References LIBMTP_file_struct::filename, LIBMTP_track_struct::filename, LIBMTP_file_struct::filesize, LIBMTP_track_struct::filesize, LIBMTP_file_struct::filetype, LIBMTP_track_struct::filetype, LIBMTP_file_struct::item_id, LIBMTP_track_struct::item_id, LIBMTP_FILETYPE_IS_TRACK, LIBMTP_Send_File_From_File_Descriptor(), LIBMTP_Update_Track_Metadata(), LIBMTP_file_struct::next, LIBMTP_mtpdevice_struct::params, LIBMTP_file_struct::parent_id, LIBMTP_track_struct::parent_id, LIBMTP_file_struct::storage_id, LIBMTP_track_struct::storage_id, and LIBMTP_mtpdevice_struct::usbinfo.

Referenced by LIBMTP_Send_Track_From_File().

## ◆ LIBMTP_Send_Track_From_Handler()

int LIBMTP_Send_Track_From_Handler | ( | LIBMTP_mtpdevice_t * | device,
|  | MTPDataGetFunc | get_func,
|  | void * | priv,
|  | LIBMTP_track_t *const | metadata,
|  | LIBMTP_progressfunc_t const | callback,
|  | void const *const | data )

This function sends a track from a handler function to an MTP device. A filename and a set of metadata must be given as input.

Parameters

  device | a pointer to the device to send the track to.
  get_func | the function to call when we have data.
  priv | the user-defined pointer that is passed to `get_func`.
  metadata | a track metadata set to be written along with the file. After this call the field `metadata->item_id` will contain the new track ID. Other fields such as the `metadata->filename`, `metadata->parent_id` or `metadata->storage_id` may also change during this operation due to device restrictions, so do not rely on the contents of this struct to be preserved in any way. `metadata->parent_id` should be set to the parent (e.g. folder) to store this track in. Since some devices are a bit picky about where files are placed, a default folder will be chosen if libmtp has detected one for the current filetype and this parameter is set to 0. If this is 0 and no default folder can be found, the file will be stored in the root folder. `metadata->storage_id` should be set to the desired storage (e.g. memory card or whatever your device presents) to store this track in. Setting this to 0 will store the track on the primary storage.
  callback | a progress indicator function or NULL to ignore.
  data | a user-defined pointer that is passed along to the `progress` function in order to pass along some user defined data to the progress updates. If not used, set this to NULL.

Returns
  0 if the transfer was successful, any other value means failure.

See also
  LIBMTP_Send_Track_From_File()
  LIBMTP_Delete_Object()

References LIBMTP_file_struct::filename, LIBMTP_track_struct::filename, LIBMTP_file_struct::filesize, LIBMTP_track_struct::filesize, LIBMTP_file_struct::filetype, LIBMTP_track_struct::filetype, LIBMTP_file_struct::item_id, LIBMTP_track_struct::item_id, LIBMTP_FILETYPE_IS_TRACK, LIBMTP_Send_File_From_Handler(), LIBMTP_Update_Track_Metadata(), LIBMTP_file_struct::next, LIBMTP_mtpdevice_struct::params, LIBMTP_file_struct::parent_id, LIBMTP_track_struct::parent_id, LIBMTP_file_struct::storage_id, LIBMTP_track_struct::storage_id, and LIBMTP_mtpdevice_struct::usbinfo.

## ◆ LIBMTP_Set_Track_Name()

int LIBMTP_Set_Track_Name | ( | LIBMTP_mtpdevice_t * | device,
|  | LIBMTP_track_t * | track,
|  | const char * | newname )

This function renames a single track. This simply means that the PTP_OPC_ObjectFileName property is updated, if this is supported by the device.

Parameters

  device | a pointer to the device that contains the file.
  track | the track metadata of the track to rename. On success, the filename member is updated. Be aware, that this name can be different than newname depending of device restrictions.
  newname | the new filename for this object.

Returns
  0 on success, any other value means failure.

References LIBMTP_track_struct::filename, LIBMTP_track_struct::filetype, and LIBMTP_track_struct::item_id.

## ◆ LIBMTP_Track_Exists()

int LIBMTP_Track_Exists | ( | LIBMTP_mtpdevice_t * | device,
|  | uint32_t const | id )

Helper function. This indicates if a track exists on the device

Parameters

  device | a pointer to the device to get the track from.
  id | the track ID of the track to retrieve.

Returns
  TRUE (!=0) if the track exists, FALSE (0) if not

References LIBMTP_mtpdevice_struct::params.

## ◆ LIBMTP_Update_Track_Metadata()

int LIBMTP_Update_Track_Metadata | ( | LIBMTP_mtpdevice_t * | device,
|  | LIBMTP_track_t const *const | metadata )

This function updates the MTP track object metadata on a single file identified by an object ID.

Parameters

  device | a pointer to the device to update the track metadata on.
  metadata | a track metadata set to be written to the file. notice that the `track_id` field of the metadata structure must be correct so that the function can update the right file. If some properties of this metadata are set to NULL (strings) or 0 (numerical values) they will be discarded and the track will not be tagged with these blank values.

Returns
  0 on success, any other value means failure. If some or all of the properties fail to update we will still return success. On some devices (notably iRiver T30) properties that exist cannot be updated.

References LIBMTP_track_struct::album, LIBMTP_track_struct::artist, LIBMTP_track_struct::bitrate, LIBMTP_track_struct::bitratetype, LIBMTP_track_struct::composer, LIBMTP_track_struct::date, LIBMTP_track_struct::duration, LIBMTP_track_struct::filetype, LIBMTP_track_struct::genre, LIBMTP_track_struct::item_id, LIBMTP_track_struct::nochannels, LIBMTP_mtpdevice_struct::params, LIBMTP_track_struct::rating, LIBMTP_track_struct::samplerate, LIBMTP_track_struct::title, LIBMTP_track_struct::tracknumber, LIBMTP_mtpdevice_struct::usbinfo, LIBMTP_track_struct::usecount, and LIBMTP_track_struct::wavecodec.

Referenced by LIBMTP_Send_Track_From_File_Descriptor(), and LIBMTP_Send_Track_From_Handler().