FFmpeg
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Functions | |
TimeFilter * | ff_timefilter_new (double time_base, double period, double bandwidth) |
Create a new Delay Locked Loop time filter. More... | |
double | ff_timefilter_update (TimeFilter *self, double system_time, double period) |
Update the filter. More... | |
double | ff_timefilter_eval (TimeFilter *self, double delta) |
Evaluate the filter at a specified time. More... | |
void | ff_timefilter_reset (TimeFilter *) |
Reset the filter. More... | |
void | ff_timefilter_destroy (TimeFilter *) |
Free all resources associated with the filter. More... | |
TimeFilter* ff_timefilter_new | ( | double | time_base, |
double | period, | ||
double | bandwidth | ||
) |
Create a new Delay Locked Loop time filter.
Where bandwidth is up to you to choose. Smaller values will filter out more of the jitter, but also take a longer time for the loop to settle. A good starting point is something between 0.3 and 3 Hz.
time_base | period of the hardware clock in seconds (for example 1.0/44100) |
period | expected update interval, in input units |
brandwidth | filtering bandwidth, in Hz |
Definition at line 46 of file timefilter.c.
Referenced by audio_read_header(), init_convert_timestamp(), main(), pulse_read_header(), and start_jack().
double ff_timefilter_update | ( | TimeFilter * | self, |
double | system_time, | ||
double | period | ||
) |
Update the filter.
This function must be called in real time, at each process cycle.
period | the device cycle duration in clock_periods. For example, at 44.1kHz and a buffer size of 512 frames, period = 512 when clock_period was 1.0/44100, or 512/44100 if clock_period was 1. |
system_time, in seconds, should be the value of the system clock time, at (or as close as possible to) the moment the device hardware interrupt occurred (or any other event the device clock raises at the beginning of a cycle).
Definition at line 72 of file timefilter.c.
Referenced by audio_read_packet(), convert_timestamp(), main(), process_callback(), and pulse_read_packet().
double ff_timefilter_eval | ( | TimeFilter * | self, |
double | delta | ||
) |
Evaluate the filter at a specified time.
delta | difference between the requested time and the current time (last call to ff_timefilter_update). |
Definition at line 88 of file timefilter.c.
Referenced by convert_timestamp().
void ff_timefilter_reset | ( | TimeFilter * | ) |
Reset the filter.
This function should mainly be called in case of XRUN.
Warning: after calling this, the filter is in an undetermined state until the next call to ff_timefilter_update()
Definition at line 67 of file timefilter.c.
Referenced by audio_read_packet(), and xrun_callback().
void ff_timefilter_destroy | ( | TimeFilter * | ) |
Free all resources associated with the filter.
Definition at line 62 of file timefilter.c.
Referenced by ff_alsa_close(), main(), pulse_close(), and stop_jack().