--- name: "njb_tagapi" section: "3" platform: "linux" package: "libnjb-doc" version: "2.2.5-4.3" release: "Debian 6.0 (Squeeze)" platforms: ["linux"] url: "https://new.carta.tech/njb_tagapi" --- # njb\_tagapi(3) ## NAME The track and tag (song ID metadata) manipulation API - ### Defines \#define **NJB\_Songid\_Frame\_New\_Title**(a) NJB\_Songid\_Frame\_New\_String(FR\_TITLE, a)\ \#define **NJB\_Songid\_Frame\_New\_Album**(a) NJB\_Songid\_Frame\_New\_String(FR\_ALBUM, a)\ \#define **NJB\_Songid\_Frame\_New\_Genre**(a) NJB\_Songid\_Frame\_New\_String(FR\_GENRE, a)\ \#define **NJB\_Songid\_Frame\_New\_Artist**(a) NJB\_Songid\_Frame\_New\_String(FR\_ARTIST, a)\ \#define **NJB\_Songid\_Frame\_New\_Length**(a) NJB\_Songid\_Frame\_New\_Uint16(FR\_LENGTH, a)\ \#define **NJB\_Songid\_Frame\_New\_Filesize**(a) NJB\_Songid\_Frame\_New\_Uint32(FR\_SIZE, a)\ \#define **NJB\_Songid\_Frame\_New\_Tracknum**(a) NJB\_Songid\_Frame\_New\_Uint16(FR\_TRACK, a)\ \#define **NJB\_Songid\_Frame\_New\_Year**(a) NJB\_Songid\_Frame\_New\_Uint16(FR\_YEAR, a)\ \#define **NJB\_Songid\_Frame\_New\_Filename**(a) NJB\_Songid\_Frame\_New\_String(FR\_FNAME, a)\ \#define **NJB\_Songid\_Frame\_New\_Protected**(a) NJB\_Songid\_Frame\_New\_Uint16(FR\_PROTECTED, a)\ \#define **NJB\_Songid\_Frame\_New\_Bitrate**(a) NJB\_Songid\_Frame\_New\_Uint32(FR\_BITRATE, a)\ \#define **NJB\_Songid\_Frame\_New\_Comment**(a) NJB\_Songid\_Frame\_New\_String(FR\_COMMENT, a)\ \#define **NJB\_Songid\_Frame\_New\_Folder**(a) NJB\_Songid\_Frame\_New\_String(FR\_FOLDER, a)\ ### Functions **njb\_songid\_t** \* **NJB\_Songid\_New** (void)\ void **NJB\_Songid\_Destroy** (**njb\_songid\_t** \*song)\ void **NJB\_Songid\_Addframe** (**njb\_songid\_t** \*song, **njb\_songid\_frame\_t** \*frame)\ void **NJB\_Songid\_Reset\_Getframe** (**njb\_songid\_t** \*song)\ **njb\_songid\_frame\_t** \* **NJB\_Songid\_Getframe** (**njb\_songid\_t** \*song)\ **njb\_songid\_frame\_t** \* **NJB\_Songid\_Findframe** (**njb\_songid\_t** \*song, const char \*label)\ **njb\_songid\_frame\_t** \* **NJB\_Songid\_Frame\_New\_String** (const char \*label, const char \*value)\ **njb\_songid\_frame\_t** \* **NJB\_Songid\_Frame\_New\_Uint16** (const char \*label, u\_int16\_t value)\ **njb\_songid\_frame\_t** \* **NJB\_Songid\_Frame\_New\_Uint32** (const char \*label, u\_int32\_t value)\ **njb\_songid\_frame\_t** \* **NJB\_Songid\_Frame\_New\_Codec** (const char \*value)\ void **NJB\_Songid\_Frame\_Destroy** (**njb\_songid\_frame\_t** \*frame)\ void **NJB\_Get\_Extended\_Tags** (**njb\_t** \*njb, int extended)\ void **NJB\_Reset\_Get\_Track\_Tag** (**njb\_t** \*njb)\ **njb\_songid\_t** \* **NJB\_Get\_Track\_Tag** (**njb\_t** \*njb)\ int **NJB\_Replace\_Track\_Tag** (**njb\_t** \*njb, u\_int32\_t trackid, **njb\_songid\_t** \*songid)\ int **NJB\_Get\_Track** (**njb\_t** \*njb, u\_int32\_t trackid, u\_int32\_t size, const char \*path, **NJB\_Xfer\_Callback** \*callback, void \*data)\ int **NJB\_Get\_Track\_fd** (**njb\_t** \*njb, u\_int32\_t trackid, u\_int32\_t size, int fd, **NJB\_Xfer\_Callback** \*callback, void \*data)\ int **NJB\_Send\_Track** (**njb\_t** \*njb, const char \*path, **njb\_songid\_t** \*songid, **NJB\_Xfer\_Callback** \*callback, void \*data, u\_int32\_t \*trackid)\ int **NJB\_Delete\_Track** (**njb\_t** \*njb, u\_int32\_t trackid)\ ## Function Documentation ### int NJB\_Delete\_Track (njb\_t \* njb, u\_int32\_t trackid) This deletes a track from the device. **Parameters:** *njb* a pointer to the `njb_t` jukebox object to use \ *trackid* the track ID for the track to delete **Returns:** 0 on success, -1 on failure **Examples:** **deltr.c**. References njb\_struct::device\_type, EO\_BADCOUNT, and NJB\_DEVICE\_NJB1. ### void NJB\_Get\_Extended\_Tags (njb\_t \* njb, int extended) This configures libnjb to retrieve extended tags from the device. For the NJB1 this is the default behaviour anyway so it need not be set, but for the series 3 devices, retrieving the extended tag information is a costly operation that will slow down the initial track scanning by orders of magnitude and irritate the user. Make sure end-users can configure whether they want to use this or not. The extended tags will include things like the filename and folder that the file used on the host before it was transfered to the device. **Parameters:** *njb* a pointer to the `njb_t` object to set this mode for \ *extended* use 0 for non-exetended tags (default), 1 for extended tags **Examples:** **tracks.c**. References njb\_struct::protocol\_state. ### int NJB\_Get\_Track (njb\_t \* njb, u\_int32\_t fileid, u\_int32\_t size, const char \* path, NJB\_Xfer\_Callback \* callback, void \* data) This retrieves ('uploads') a track from the device to the host computer. **Parameters:** *njb* a pointer to the `njb_t` object to get the track from \ *fileid* the unique trackid (also known as file ID, they are the same things) as reported by the device from e.g. **NJB\_Get\_Track\_Tag().** \ *size* **the size of the track in bytes. You know this size from previous calls to NJB\_Get\_Track\_Tag() and it is needed among other things for displaying a progress bar and for determining that all bytes have been correctly retrieved.** \ *path* **the path where the resulting file should be written. If this parameter is null, the blocks are delivered via the callback's buf parameter.** \ *callback* **a function that will be called repeatedly to report progress during transfer, used for e.g. displaying progress bars** \ *data* **a voluntary parameter that can associate some user-supplied data with each callback call. It is OK to set this to NULL of course.** **Returns:** **0 on success, -1 on failure** **See also:** **NJB\_Get\_Track\_fd()** **Examples:** **gettr.c.** **References EO\_TMPFILE, and NJB\_Get\_Track\_fd().** ### int NJB\_Get\_Track\_fd (njb\_t \* njb, u\_int32\_t fileid, u\_int32\_t size, int fd, NJB\_Xfer\_Callback \* callback, void \* data) This retrieves ('uploads') a track from the device to the host computer by way of a file descriptor, which is good for e.g. streaming stuff. The daring type can start playing back audio from the file descriptor before it is finished. This is also good for fetching to temporary files, which are often only given as file descriptors. **Parameters:** *njb* **a pointer to the** `njb_t` **object to get the track from** \ *fileid* **the unique trackid (also known as file ID, they are the same things) as reported by the device from e.g. NJB\_Get\_Track\_Tag().** \ *size* **the size of the track in bytes. You know this size from previous calls to NJB\_Get\_Track\_Tag() and it is needed among other things for displaying a progress bar and for determining that all bytes have been correctly retrieved.** \ *fd* **the file descriptor that shall be fed with the track contents. The file descriptor must be writable. On win32 make sure it is a binary descriptor and not textual.** \ *callback* **a function that will be called repeatedly to report progress during transfer, used for e.g. displaying progress bars** \ *data* **a voluntary parameter that can associate some user-supplied data with each callback call. It is OK to set this to NULL of course.** **Returns:** **0 on success, -1 on failure** **See also:** **NJB\_Get\_Track()** **References njb\_struct::device\_type, EO\_ABORTED, EO\_NOMEM, EO\_WRFILE, EO\_XFERDENIED, EO\_XFERERROR, njb3\_get\_file\_block(), njb3\_request\_file\_chunk(), NJB\_DEVICE\_NJB1, njb\_receive\_file\_block(), NJB\_TURBO\_OFF, njb\_verify\_last\_command(), njb\_struct::protocol\_state, and njb3\_state\_t::turbo\_mode.** **Referenced by NJB\_Get\_Track().** ### njb\_songid\_t\* NJB\_Get\_Track\_Tag (njb\_t \* njb) This gets a track tag (song ID) from the device. The device should first be rewound using the NJB\_Reset\_Get\_Track\_Tag() function. **Notice that there is no function for getting the tag for a** *single* **track, there is just this function that dumps out the entire database in one big go. The recommended approach is to keep an internal track cache of all tracks and use this for getting metadata for single tracks. There is as far as we know no function in the Creative firmwares for getting the metadata of a single track, so access through this function is the only option.** **Parameters:** *njb* **a pointer to the** `njb_t` **object to reset the track retrieveal pointer for** **Returns:** **a track tag (song ID) or NULL if the last track tag has already been retrieved** **See also:** **NJB\_Reset\_Get\_Track\_Tag()** **Examples:** **gettr.c, and tracks.c.** **References njb\_struct::device\_type, NJB\_DEVICE\_NJB1, and njb\_struct::protocol\_state.** ### int NJB\_Replace\_Track\_Tag (njb\_t \* njb, u\_int32\_t trackid, njb\_songid\_t \* songid) This routine will replace the track tag or parts of a track tag for a track that already exist on the device. On the NJB1 the whole metadata set must be specified for this routine to work properly, but on the series 3 devices you can specify incremental updates (only parts of the metadata set). Be sure to either specify the full set all the time, or check if we are handling an NJB1 before submitting an incremental update (see example below). **Parameters:** *njb* **a pointer to the jukebox object to use** \ *trackid* **the track ID to replace the tag for** \ *songid* **the new tag** **Typical usage:** ``` njb_t *njb; njb_songid_t *songid; njb_songid_frame_t *frame; ``` ``` songid = NJB_Songid_New(); // On NJB1 incremental update is not possible, so a full // metadata set must always be specified. if (njb->device_type == NJB_DEVICE_NJB1) { frame = NJB_Songid_Frame_New_Codec(meta->codec); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Filesize(meta->size); NJB_Songid_Addframe(songid, frame); } frame = NJB_Songid_Frame_New_Codec(NJB_CODEC_MP3); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Title('MyTitle'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Album('MyAlbum'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Artist('MyArtist'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Genre('MyGenre'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Year(2004); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Tracknum(1); NJB_Songid_Addframe(songid, frame); // The length of the track should typically be given, or such things // as progress indicators will stop working. If you absolutely want to // upload a file of unknown length and break progress indicators, set // length to 1 second. frame = NJB_Songid_Frame_New_Length(123); NJB_Songid_Addframe(songid, frame); // This one is optional, the track will survive without it. frame = NJB_Songid_Frame_New_Filename('Foo.mp3'); NJB_Songid_Addframe(songid, frame); if (NJB_Replace_Track_Tag(njb, 123456, songid) == -1) { NJB_Error_Dump(stderr); } NJB_Songid_Destroy(songid); ``` **Examples:** **tagtr.c.** **References njb\_songid\_frame\_struct::data, njb\_struct::device\_type, EO\_BAD\_NJB1\_REPLACE, EO\_BADCOUNT, FR\_CODEC, njb\_songid\_frame\_struct::label, njb3\_update\_tag(), NJB\_DEVICE\_NJB1, NJB\_Songid\_Addframe(), NJB\_Songid\_Destroy(), NJB\_Songid\_Frame\_New\_String(), NJB\_Songid\_Frame\_New\_Uint16(), NJB\_Songid\_Frame\_New\_Uint32(), NJB\_Songid\_Getframe(), NJB\_Songid\_New(), NJB\_Songid\_Reset\_Getframe(), NJB\_TYPE\_STRING, NJB\_TYPE\_UINT16, NJB\_TYPE\_UINT32, songid\_pack(), songid\_pack3(), songid\_sanity\_check(), njb\_songid\_frame\_struct::strval, njb\_songid\_frame\_struct::type, njb\_songid\_frame\_struct::u\_int16\_val, and njb\_songid\_frame\_struct::u\_int32\_val.** ### void NJB\_Reset\_Get\_Track\_Tag (njb\_t \* njb) This resets the track tag (song ID) retrieveal function. The track tags can then be retrieved one by one using the NJB\_Get\_Track\_Tag() function. **Typical usage:** ``` njb_t *njb; njb_songid_t *song; ``` ``` NJB_Songid_Reset_Get_Track_Tag(njb); while ( (song = NJB_Get_Track_Tag(njb)) != NULL ) { // Do something with all the songs... } ``` **Parameters:** *njb* **a pointer to the** `njb_t` **object to reset the track retrieveal pointer for** **See also:** **NJB\_Get\_Track\_Tag()** **Examples:** **gettr.c, and tracks.c.** **References njb\_struct::device\_type, NJB\_DEVICE\_NJB1, and njb\_struct::protocol\_state.** ### int NJB\_Send\_Track (njb\_t \* njb, const char \* path, njb\_songid\_t \* songid, NJB\_Xfer\_Callback \* callback, void \* data, u\_int32\_t \* trackid) This sends ('downloads') a track (playable music file) to the device. **Typical usage:** ``` njb_t *njb; njb_songid_t *songid; njb_songid_frame_t *frame; u_int32_t id; ``` ``` songid = NJB_Songid_New(); frame = NJB_Songid_Frame_New_Codec(NJB_CODEC_MP3); NJB_Songid_Addframe(songid, frame); // This one is optional - libnjb will fill it in if not specified frame = NJB_Songid_Frame_New_Filesize(12345678); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Title('MyTitle'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Album('MyAlbum'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Artist('MyArtist'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Genre('MyGenre'); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Year(2004); NJB_Songid_Addframe(songid, frame); frame = NJB_Songid_Frame_New_Tracknum(1); NJB_Songid_Addframe(songid, frame); // The length of the track should typically be given, or such things // as progress indicators will stop working. If you absolutely want to // upload a file of unknown length and break progress indicators, set // length to 1 second. frame = NJB_Songid_Frame_New_Length(123); NJB_Songid_Addframe(songid, frame); // This one is optional - libnjb will fill it in if not specified frame = NJB_Songid_Frame_New_Filename('Foo.mp3'); NJB_Songid_Addframe(songid, frame); if (NJB_Send_Track (njb, 'foo.mp3', songid, NULL, NULL, &id) == -1) { NJB_Error_Dump(stderr); } NJB_Songid_Destroy(songid); ``` **Parameters:** *njb* **a pointer to the** `njb_t` **object to send the track file to.** \ *path* **the filesystem path on the local host to use as indata** \ *songid* **the tag for this track, which has to be built separately before the transfer is started with a call to this function.** \ *callback* **a function that will be called repeatedly to report progress during transfer, used for e.g. displaying progress bars. This may be NULL if you don't want any callbacks.** \ *data* **a voluntary parameter that can associate some user-supplied data with each callback call. It is OK to set this to NULL of course.** \ *trackid* **a pointer to an integer that will hold the resulting track ID after this transfer has commenced successfully.** **Returns:** **0 on success, -1 on failure** **See also:** **NJB\_Send\_File()** **Examples:** **sendtr.c.** **References \_file\_size(), njb\_struct::device\_type, EO\_INVALID, EO\_SRCFILE, EO\_TOOBIG, EO\_XFERDENIED, FR\_FNAME, FR\_SIZE, NJB\_DEVICE\_NJB1, NJB\_Get\_Disk\_Usage(), NJB\_Songid\_Addframe(), NJB\_Songid\_Findframe(), songid\_pack(), songid\_pack3(), and songid\_sanity\_check().** ### void NJB\_Songid\_Addframe (njb\_songid\_t \* song, njb\_songid\_frame\_t \* frame) This adds a song ID frame to a song ID. **Parameters:** *song* **the song ID to add the frame to** \ *frame* **the frame to add to this song ID** **Examples:** **sendtr.c, and tagtr.c.** **References njb\_songid\_struct::cur, njb\_songid\_struct::first, njb\_songid\_struct::last, njb\_songid\_frame\_struct::next, and njb\_songid\_struct::nframes.** **Referenced by NJB\_Replace\_Track\_Tag(), NJB\_Send\_Track(), songid\_sanity\_check(), and songid\_unpack().** ### void NJB\_Songid\_Destroy (njb\_songid\_t \* songid) This destroys an entire song ID structure and free the memory used by it. **Parameters:** *songid* **the song ID structure to destroy** **Examples:** **gettr.c, sendtr.c, tagtr.c, and tracks.c.** **References NJB\_Songid\_Frame\_Destroy(), NJB\_Songid\_Getframe(), and NJB\_Songid\_Reset\_Getframe().** **Referenced by NJB\_Replace\_Track\_Tag(), and songid\_unpack().** ### njb\_songid\_frame\_t\* NJB\_Songid\_Findframe (njb\_songid\_t \* song, const char \* label) This locates a particular song ID frame inside a song ID, by using the textual label given. **Parameters:** *song* **the song ID to look in** \ *label* **the textual label of the frame to look for** **Returns:** **the song ID frame if found, else NULL** **Examples:** **gettr.c.** **References njb\_songid\_frame\_struct::label, NJB\_Songid\_Getframe(), and NJB\_Songid\_Reset\_Getframe().** **Referenced by NJB\_Send\_Track().** ### void NJB\_Songid\_Frame\_Destroy (njb\_songid\_frame\_t \* frame) This destroys a song ID frame and free any memory used by it. **Parameters:** *frame* **the song ID frame to destroy** **References njb\_songid\_frame\_struct::data, njb\_songid\_frame\_struct::label, NJB\_TYPE\_STRING, njb\_songid\_frame\_struct::strval, and njb\_songid\_frame\_struct::type.** **Referenced by NJB\_Songid\_Destroy().** ### njb\_songid\_frame\_t\* NJB\_Songid\_Frame\_New\_Codec (const char \* value) This is a wrapper function to fix a common mistake made when creating codec frames: lowercase codec names and other strange mistakes. **Examples:** **sendtr.c, and tagtr.c.** **References FR\_CODEC, NJB\_CODEC\_MP3, NJB\_CODEC\_WAV, NJB\_CODEC\_WMA, and NJB\_Songid\_Frame\_New\_String().** ### njb\_songid\_frame\_t\* NJB\_Songid\_Frame\_New\_String (const char \* label, const char \* value) Creates a new string frame. **Parameters:** *label* **the label of this string frame** \ *value* **the string contained in this string frame** **Returns:** **valid string frame on success, NULL on failure** **References njb\_songid\_frame\_struct::data, njb\_songid\_frame\_struct::label, NJB\_TYPE\_STRING, njb\_songid\_frame\_struct::strval, and njb\_songid\_frame\_struct::type.** **Referenced by NJB\_Replace\_Track\_Tag(), NJB\_Songid\_Frame\_New\_Codec(), and songid\_unpack().** ### njb\_songid\_frame\_t\* NJB\_Songid\_Frame\_New\_Uint16 (const char \* label, u\_int16\_t value) Creates a new unsigned 16-bit integer frame. **Parameters:** *label* **the label of this unsigned 16-bit integer frame** \ *value* **the unsigned 16-bit integer contained in this frame** **Returns:** **valid unsigned 16-bit integer frame on success, NULL on failure** **References njb\_songid\_frame\_struct::data, njb\_songid\_frame\_struct::label, NJB\_TYPE\_UINT16, njb\_songid\_frame\_struct::type, and njb\_songid\_frame\_struct::u\_int16\_val.** **Referenced by NJB\_Replace\_Track\_Tag(), and songid\_unpack().** ### njb\_songid\_frame\_t\* NJB\_Songid\_Frame\_New\_Uint32 (const char \* label, u\_int32\_t value) Creates a new unsigned 32-bit integer frame. **Parameters:** *label* **the label of this unsigned 32-bit integer frame** \ *value* **the unsigned 32-bit integer contained in this frame** **Returns:** **valid unsigned 32-bit integer frame on success, NULL on failure** **References njb\_songid\_frame\_struct::data, njb\_songid\_frame\_struct::label, NJB\_TYPE\_UINT32, njb\_songid\_frame\_struct::type, and njb\_songid\_frame\_struct::u\_int32\_val.** **Referenced by NJB\_Replace\_Track\_Tag(), and songid\_unpack().** ### njb\_songid\_frame\_t\* NJB\_Songid\_Getframe (njb\_songid\_t \* song) This gets the next song ID frame from a song ID structure. **Parameters:** *song* **the song ID to get frames from** **Returns:** **a song ID frame, or NULL if the last frame has already been returned.** **See also:** **NJB\_Songid\_Reset\_Getframe()** **Examples:** **tracks.c.** **References njb\_songid\_struct::cur, and njb\_songid\_frame\_struct::next.** **Referenced by NJB\_Replace\_Track\_Tag(), NJB\_Songid\_Destroy(), NJB\_Songid\_Findframe(), songid\_pack(), songid\_pack3(), and songid\_sanity\_check().** ### njb\_songid\_t\* NJB\_Songid\_New (void) This creates a new song ID holder structure. (A songid in turn contains several frames represening different metadata.) **Returns:** **a new song ID structure** **Examples:** **sendtr.c, and tagtr.c.** **References njb\_songid\_struct::next.** **Referenced by NJB\_Replace\_Track\_Tag(), and songid\_unpack().** ### void NJB\_Songid\_Reset\_Getframe (njb\_songid\_t \* song) This resets the internal pointer in the song ID so that it points to the first frame of the song ID. It should typically be called before subsequent calls to NJB\_Songid\_Getframe(). **Typical usage:** ``` njb_songid_t *song; njb_songid_frame_t *frame; ``` ``` // Get a song ID into 'song'... NJB_Songid_Reset_Getframe(song); while ( (frame = NJB_Songid_Getframe(song)) != NULL ) { // Do something with all the frames... } ``` **Parameters:** *song* **the song ID structure whose internal frame pointer shall be reset.** **See also:** **NJB\_Songid\_Getframe()** **Examples:** **tracks.c.** **References njb\_songid\_struct::cur, and njb\_songid\_struct::first.** **Referenced by NJB\_Replace\_Track\_Tag(), NJB\_Songid\_Destroy(), NJB\_Songid\_Findframe(), songid\_pack(), songid\_pack3(), and songid\_sanity\_check().** ## Author **Generated automatically by Doxygen for libnjb from the source code.**