NAME
The track playback (listening) API -
Functions
int NJB_Play_Track (njb_t *njb, u_int32_t trackid)
int NJB_Queue_Track (njb_t *njb, u_int32_t trackid)
int NJB_Stop_Play (njb_t *njb)
int NJB_Pause_Play (njb_t *njb)
int NJB_Resume_Play (njb_t *njb)
int NJB_Seek_Track (njb_t *njb, u_int32_t position)
int NJB_Elapsed_Time (njb_t *njb, u_int16_t *elapsed, int *change)
Function Documentation
int NJB_Elapsed_Time (njb_t * njb, u_int16_t * elapsed, int * change) This
function returns the elapsed time for the currently playing track on
the device. Additionally, it signals if the track has changed, e.g. if
the device has skipped to the next track in the queue.
Currently, it may only be determined if the currently playing track in
the Nomad’s play queue has changed (or ended) from a previous call to
NJB_Elapsed_Time, because the indicator is that the elapsed time goes
from a greater number to a lower number. Typically, when the first
(zeroth) track in the play queue ends, the elapsed time is set to zero,
and the change bit is set. However, if the zeroth track is the only
track on the play queue, it must be more than 1 second long and
NJB_Elapsed_Time must have been called at least once after 1 second
actually has elapsed to register the change (song end) on a subsequent
call to NJB_Elapsed_Time.
NOTE, the elapsed time will NOT always be zero when the change bit is
set, as a call to NJB_Elapsed_Time may arrive late after a song has
started.
NOTE, after NJB_Play_Track is called an immediate call NJB_Elapsed_Time
will not indicate change, even if there was a track playing previously.
Obviously, this notification of change scheme is a flawed one, and some
Nomad play queue management functions, such as finding out the actual
trackid playing on the Nomad would be favored over this approach. One
should not really rely too heavily on this approach.
Parameters:
njb a pointer to the jukebox object that the track is playing on.
elapsed a pointer to a variable that will hold the number of
elapsed seconds after the call to this function.
change a pointer to a variable that will hold 0 if the track has
not changed, and something different from 0 if the track has
changed.
Returns:
0 on success, -1 on failure.
Examples:
cursesplay.c, and play.c.
References njb_struct::device_type, and NJB_DEVICE_NJB1.
int NJB_Pause_Play (njb_t * njb) This pauses the current playback of a
track on the device.
Parameters:
njb a pointer to the jukebox object to play the track on.
Returns:
0 on success, -1 on failure.
See also:
NJB_Resume_Play()
NJB_Stop_Play()
Examples:
cursesplay.c.
int NJB_Play_Track (njb_t * njb, u_int32_t trackid) This starts playing a
certain track on the device. This command will implicitly clear any
pending or playing playback queue. You may queue up other songs using
NJB_Queue_Track() while the first track is playing. The track on which
you called NJB_Play_Track() will implicitly be placed first in the
queue.
Parameters:
njb a pointer to the jukebox object to play the track on.
trackid the track to play.
Returns:
0 on success, -1 on failure.
See also:
NJB_Queue_Track()
NJB_Stop_Play()
NJB_Pause_Play()
NJB_Seek_Track()
NJB_Elapsed_Time()
Examples:
cursesplay.c, and play.c.
References njb_struct::device_type, NJB_DEVICE_NJB1, and
njb_verify_last_command().
int NJB_Queue_Track (njb_t * njb, u_int32_t trackid) This adds a track to
the play queue of a device.
Parameters:
njb a pointer to the jukebox object to play the track on.
trackid the track to add to the queue.
Returns:
0 on success, -1 on failure.
Examples:
cursesplay.c, and play.c.
References njb_struct::device_type, NJB_DEVICE_NJB1, and
njb_verify_last_command().
int NJB_Resume_Play (njb_t * njb) This resumes play of a track on the
device after pause.
Parameters:
njb a pointer to the jukebox object to resume the track on.
Returns:
0 on success, -1 on failure.
See also:
NJB_Pause_Play()
Examples:
cursesplay.c.
int NJB_Seek_Track (njb_t * njb, u_int32_t position) This seeks into an
offset of the currenly playing track on the device. You can skip to an
offset forward/backward in the currently playing file, given as
milliseconds.
Parameters:
njb a pointer to the jukebox object to stop the current playing
track on.
position the position in the track file given as milliseconds.
Offsets larger than the file length should not be used.
Returns:
0 on success, -1 on failure.
Examples:
cursesplay.c.
int NJB_Stop_Play (njb_t * njb) This stops playback of a track on the
device.
Parameters:
njb a pointer to the jukebox object to stop the current playing
track on.
Returns:
0 on success, -1 on failure.
See also:
NJB_Pause_Play()
Examples:
cursesplay.c, and play.c.
References njb_struct::device_type, and NJB_DEVICE_NJB1.
Author
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Version 2.2.5 6 Mar 2The track playback (listening) API(3)