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JACK-AUDIO-CONNECTION-KIT
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JACK-AUDIO-CONNECTION-KIT
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Data Structures | |
| struct | jack_transport_info_t |
Typedefs | |
| typedef int(* | JackSyncCallback) (jack_transport_state_t state, jack_position_t *pos, void *arg) |
| typedef void(* | JackTimebaseCallback) (jack_transport_state_t state, jack_nframes_t nframes, jack_position_t *pos, int new_pos, void *arg) |
Enumerations | |
| enum | jack_transport_bits_t { JackTransportState = 0x1 , JackTransportPosition = 0x2 , JackTransportLoop = 0x4 , JackTransportSMPTE = 0x8 , JackTransportBBT = 0x10 } |
Server-set fields | |
| jack_unique_t | jack_position_t::unique_1 |
| jack_time_t | jack_position_t::usecs |
| jack_nframes_t | jack_position_t::frame_rate |
Mandatory fields | |
| jack_nframes_t | jack_position_t::frame |
| jack_position_bits_t | jack_position_t::valid |
JackPositionBBT fields | |
Bar:Beat.Tick-related information. Applications that support JackPositionBBT are encouraged to also fill the JackBBTFrameOffset | |
| int32_t | jack_position_t::bar |
| int32_t | jack_position_t::beat |
| int32_t | jack_position_t::tick |
| double | jack_position_t::bar_start_tick |
| float | jack_position_t::beats_per_bar |
| float | jack_position_t::beat_type |
| double | jack_position_t::ticks_per_beat |
| double | jack_position_t::beats_per_minute |
JackPositionTimecode fields <br> | |
| double | jack_position_t::frame_time |
| double | jack_position_t::next_time |
| jack_nframes_t | jack_position_t::bbt_offset |
| float | jack_position_t::audio_frames_per_video_frame |
| jack_nframes_t | jack_position_t::video_offset |
JACK Extra transport fields | |
| double | jack_position_t::tick_double |
Other fields | |
| int32_t | jack_position_t::padding [5] |
| jack_unique_t | jack_position_t::unique_2 |
| typedef int(* JackSyncCallback) (jack_transport_state_t state, jack_position_t *pos, void *arg) |
Prototype for the sync_callback defined by slow-sync clients. When the client is active, this callback is invoked just before process() in the same thread. This occurs once after registration, then subsequently whenever some client requests a new position, or the transport enters the JackTransportStarting state. This realtime function must not wait.
The transport state will be:
| state | current transport state. |
| pos | new transport position. |
| arg | the argument supplied by jack_set_sync_callback(). |
| typedef void(* JackTimebaseCallback) (jack_transport_state_t state, jack_nframes_t nframes, jack_position_t *pos, int new_pos, void *arg) |
Prototype for the timebase_callback used to provide extended position information. Its output affects all of the following process cycle. This realtime function must not wait.
This function is called immediately after process() in the same thread whenever the transport is rolling, or when any client has requested a new position in the previous cycle. The first cycle after jack_set_timebase_callback() is also treated as a new position, or the first cycle after jack_activate() if the client had been inactive.
The timebase master may not use its pos argument to set pos->frame. To change position, use jack_transport_reposition() or jack_transport_locate(). These functions are realtime-safe, the timebase_callback can call them directly.
| state | current transport state. |
| nframes | number of frames in current period. |
| pos | address of the position structure for the next cycle; pos->frame will be its frame number. If new_pos is FALSE, this structure contains extended position information from the current cycle. If TRUE, it contains whatever was set by the requester. The timebase_callback's task is to update the extended information here. |
| new_pos | TRUE (non-zero) for a newly requested pos, or for the first cycle after the timebase_callback is defined. |
| arg | the argument supplied by jack_set_timebase_callback(). |
Optional struct jack_transport_info_t fields.
| Enumerator | |
|---|---|
| JackTransportState | Transport state |
| JackTransportPosition | Frame number |
| JackTransportLoop | Loop boundaries (ignored) |
| JackTransportSMPTE | SMPTE (ignored) |
| JackTransportBBT | Bar, Beat, Tick |
| jack_nframes_t jack_get_current_transport_frame | ( | const jack_client_t * | client | ) |
Return an estimate of the current transport frame, including any time elapsed since the last transport positional update.
| client | the JACK client structure |
| void jack_get_transport_info | ( | jack_client_t * | client, |
| jack_transport_info_t * | tinfo | ||
| ) |
Gets the current transport info structure (deprecated).
| client | the JACK client structure. |
| tinfo | current transport info structure. The "valid" field describes which fields contain valid data. |
| int jack_release_timebase | ( | jack_client_t * | client | ) |
Called by the timebase master to release itself from that responsibility.
If the timebase master releases the timebase or leaves the JACK graph for any reason, the JACK engine takes over at the start of the next process cycle. The transport state does not change. If rolling, it continues to play, with frame numbers as the only available position information.
| client | the JACK client structure. |
| int jack_set_sync_callback | ( | jack_client_t * | client, |
| JackSyncCallback | sync_callback, | ||
| void * | arg | ||
| ) |
Register (or unregister) as a slow-sync client, that cannot respond immediately to transport position changes.
The sync_callback will be invoked at the first available opportunity after its registration is complete. If the client is currently active this will be the following process cycle, otherwise it will be the first cycle after calling jack_activate(). After that, it runs according to the JackSyncCallback rules. Clients that don't set a sync_callback are assumed to be ready immediately any time the transport wants to start.
| client | the JACK client structure. |
| sync_callback | is a realtime function that returns TRUE when the client is ready. Setting sync_callback to NULL declares that this client no longer requires slow-sync processing. |
| arg | an argument for the sync_callback function. |
| int jack_set_sync_timeout | ( | jack_client_t * | client, |
| jack_time_t | timeout | ||
| ) |
Set the timeout value for slow-sync clients.
This timeout prevents unresponsive slow-sync clients from completely halting the transport mechanism. The default is two seconds. When the timeout expires, the transport starts rolling, even if some slow-sync clients are still unready. The sync_callbacks of these clients continue being invoked, giving them a chance to catch up.
| client | the JACK client structure. |
| timeout | is delay (in microseconds) before the timeout expires. |
| int jack_set_timebase_callback | ( | jack_client_t * | client, |
| int | conditional, | ||
| JackTimebaseCallback | timebase_callback, | ||
| void * | arg | ||
| ) |
Register as timebase master for the JACK subsystem.
The timebase master registers a callback that updates extended position information such as beats or timecode whenever necessary. Without this extended information, there is no need for this function.
There is never more than one master at a time. When a new client takes over, the former timebase_callback is no longer called. Taking over the timebase may be done conditionally, so it fails if there was a master already.
The method may be called whether the client has been activated or not.
| client | the JACK client structure. |
| conditional | non-zero for a conditional request. |
| timebase_callback | is a realtime function that returns position information. |
| arg | an argument for the timebase_callback function. |
| void jack_set_transport_info | ( | jack_client_t * | client, |
| jack_transport_info_t * | tinfo | ||
| ) |
Set the transport info structure (deprecated).
| int jack_transport_locate | ( | jack_client_t * | client, |
| jack_nframes_t | frame | ||
| ) |
Reposition the transport to a new frame number.
May be called at any time by any client. The new position takes effect in two process cycles. If there are slow-sync clients and the transport is already rolling, it will enter the JackTransportStarting state and begin invoking their sync_callbacks until ready. This function is realtime-safe.
| client | the JACK client structure. |
| frame | frame number of new transport position. |
| jack_transport_state_t jack_transport_query | ( | const jack_client_t * | client, |
| jack_position_t * | pos | ||
| ) |
Query the current transport state and position.
This function is realtime-safe, and can be called from any thread. If called from the process thread, pos corresponds to the first frame of the current cycle and the state returned is valid for the entire cycle.
| client | the JACK client structure. |
| pos | pointer to structure for returning current transport position; pos->valid will show which fields contain valid data. If pos is NULL, do not return position information. |
| int jack_transport_reposition | ( | jack_client_t * | client, |
| const jack_position_t * | pos | ||
| ) |
Request a new transport position.
May be called at any time by any client. The new position takes effect in two process cycles. If there are slow-sync clients and the transport is already rolling, it will enter the JackTransportStarting state and begin invoking their sync_callbacks until ready. This function is realtime-safe.
| client | the JACK client structure. |
| pos | requested new transport position. Fill pos->valid to specify which fields should be taken into account. If you mark a set of fields as valid, you are expected to fill them all. |
| void jack_transport_start | ( | jack_client_t * | client | ) |
Start the JACK transport rolling.
Any client can make this request at any time. It takes effect no sooner than the next process cycle, perhaps later if there are slow-sync clients. This function is realtime-safe.
| client | the JACK client structure. |
| void jack_transport_stop | ( | jack_client_t * | client | ) |
Stop the JACK transport.
Any client can make this request at any time. It takes effect on the next process cycle. This function is realtime-safe.
| client | the JACK client structure. |
| float jack_position_t::audio_frames_per_video_frame |
number of audio frames per video frame. Should be assumed zero if JackAudioVideoRatio is not set. If JackAudioVideoRatio is set and the value is zero, no video data exists within the JACK graph
| int32_t jack_position_t::bar |
current bar
Should be >0: the first bar is bar '1'.
| int jack_transport_info_t::bar |
| double jack_position_t::bar_start_tick |
number of ticks that have elapsed between frame 0 and the first beat of the current measure.
| double jack_transport_info_t::bar_start_tick |
| jack_nframes_t jack_position_t::bbt_offset |
frame offset for the BBT fields (the given bar, beat, and tick values actually refer to a time frame_offset frames before the start of the cycle), should be assumed to be 0 if JackBBTFrameOffset is not set. If JackBBTFrameOffset is set and this value is zero, the BBT time refers to the first frame of this cycle. If the value is positive, the BBT time refers to a frame that many frames before the start of the cycle.
| int32_t jack_position_t::beat |
current beat-within-bar
Should be >0 and <=beats_per_bar: the first beat is beat '1'.
| int jack_transport_info_t::beat |
| float jack_position_t::beat_type |
time signature "denominator"
| float jack_transport_info_t::beat_type |
| float jack_position_t::beats_per_bar |
time signature "numerator"
| float jack_transport_info_t::beats_per_bar |
| double jack_position_t::beats_per_minute |
BPM, quantized to block size. This means when the tempo is not constant within this block, the BPM value should adapted to compensate for this. This is different from most fields in this struct, which specify the value at the beginning of the block rather than an average.
| double jack_transport_info_t::beats_per_minute |
| jack_nframes_t jack_position_t::frame |
frame number, always present/required.
This is the frame number on the transport timeline, which is not the same as what jack_frame_time returns.
| jack_nframes_t jack_transport_info_t::frame |
| jack_nframes_t jack_position_t::frame_rate |
current frame rate, in frames per second
| jack_nframes_t jack_transport_info_t::frame_rate |
current frame rate (per second)
| double jack_position_t::frame_time |
current time in seconds
| jack_nframes_t jack_transport_info_t::loop_end |
| jack_nframes_t jack_transport_info_t::loop_start |
| double jack_position_t::next_time |
next sequential frame_time (unless repositioned)
| int32_t jack_position_t::padding[5] |
| float jack_transport_info_t::smpte_frame_rate |
29.97, 30, 24 etc.
| long jack_transport_info_t::smpte_offset |
SMPTE offset (from frame 0)
| int32_t jack_position_t::tick |
current tick-within-beat
Should be >= 0 and < ticks_per_beat: the first tick is tick '0'.
| int jack_transport_info_t::tick |
| double jack_position_t::tick_double |
current tick-within-beat in double resolution. Should be assumed zero if JackTickDouble is not set. Since older versions of JACK do not expose this variable, the macro JACK_TICK_DOUBLE is provided, which can be used as build-time detection.
| double jack_position_t::ticks_per_beat |
number of ticks within a beat.
Usually a moderately large integer with many denominators, such as 1920.0
| double jack_transport_info_t::ticks_per_beat |
| jack_transport_state_t jack_transport_info_t::transport_state |
| jack_unique_t jack_position_t::unique_1 |
unique ID
| jack_unique_t jack_position_t::unique_2 |
unique ID
| jack_time_t jack_position_t::usecs |
microsecond timestamp that is guaranteed to be monotonic, but not neccessarily linear.
The absolute value is implementation-dependent (i.e. it could be wall-clock, time since jack started, uptime, etc).
| jack_time_t jack_transport_info_t::usecs |
monotonic, free-rolling
| jack_position_bits_t jack_position_t::valid |
which other fields are valid, as a bitmask constructed from values in jack_position_bits_t
| jack_transport_bits_t jack_transport_info_t::valid |
which fields are legal to read
| jack_nframes_t jack_position_t::video_offset |
audio frame at which the first video frame in this cycle occurs. Should be assumed to be 0 if JackVideoFrameOffset is not set. If JackVideoFrameOffset is set, but the value is zero, there is no video frame within this cycle.
1.9.1
