1. ffmpeg
  2. Commit 08ffd3708bd15613e85e331b04c89fbde2054b30
Browse code

Allow timespans to vary. No change in performance if they do not vary.

Originally committed as revision 17840 to svn://svn.ffmpeg.org/ffmpeg/trunk

Michael Niedermayer authored on 2009/03/06 09:09:14
Showing 2 changed files
libavformat/timefilter.c
History View file @ 08ffd37
... ... 
@@ -34,10 +34,10 @@ struct TimeFilter {
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     double integrator2_state;
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 };
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-TimeFilter * ff_timefilter_new(double period, double feedback2_factor, double feedback3_factor)
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+TimeFilter * ff_timefilter_new(double feedback2_factor, double feedback3_factor)
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 {
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     TimeFilter *self        = av_mallocz(sizeof(TimeFilter));
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-    self->integrator2_state = period;
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+    self->integrator2_state = 1.0;
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     self->feedback2_factor  = feedback2_factor;
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     self->feedback3_factor  = feedback3_factor;
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     return self;
... ... 
@@ -53,20 +53,20 @@ void ff_timefilter_reset(TimeFilter *self)
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     self->cycle_time = 0;
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 }
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-void ff_timefilter_update(TimeFilter *self, double system_time)
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+void ff_timefilter_update(TimeFilter *self, double system_time, double period)
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 {
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     if (!self->cycle_time) {
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         /// init loop
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         self->cycle_time        = system_time;
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     } else {
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         double loop_error;
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-        self->cycle_time+= self->integrator2_state;
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+        self->cycle_time+= self->integrator2_state * period;
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         /// calculate loop error
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         loop_error = system_time - self->cycle_time;
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         /// update loop
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         self->cycle_time        += self->feedback2_factor * loop_error;
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-        self->integrator2_state += self->feedback3_factor * loop_error;
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+        self->integrator2_state += self->feedback3_factor * loop_error / period;
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     }
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 }
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libavformat/timefilter.h
History View file @ 08ffd37
... ... 
@@ -37,10 +37,6 @@ typedef struct TimeFilter TimeFilter;
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 /**
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  * Create a new Delay Locked Loop time filter
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  *
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- * period is the device cycle duration in seconds. For example, at
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- * 44.1Hz and a buffer size of 512 frames, period = 512 / 44100. The filter
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- * only works if the cycle duration is fixed.
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- *
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  * feedback2_factor and feedback3_factor are the factors used for the
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  * multiplications that are respectively performed in the second and third
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  * feedback paths of the loop.
... ... 
@@ -58,19 +54,22 @@ typedef struct TimeFilter TimeFilter;
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  * For more details about these parameters and background concepts please see:
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  * http://www.kokkinizita.net/papers/usingdll.pdf
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  */
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-TimeFilter * ff_timefilter_new(double period, double feedback2_factor, double feedback3_factor);
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+TimeFilter * ff_timefilter_new(double feedback2_factor, double feedback3_factor);
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 /**
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  * Update the filter
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  *
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  * This function must be called in real time, at each process cycle.
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  *
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+ * period is the device cycle duration in seconds. For example, at
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+ * 44.1Hz and a buffer size of 512 frames, period = 512 / 44100.
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+ *
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  * system_time, in seconds, should be the value of the system clock time,
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  * at (or as close as possible to) the moment the device hardware interrupt
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  * occured (or any other event the device clock raises at the beginning of a
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  * cycle).
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  */
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-void ff_timefilter_update(TimeFilter *self, double system_time);
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+void ff_timefilter_update(TimeFilter *self, double system_time, double period);
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 /**
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  * Retrieve the filtered time