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74 lines
2.3 KiB
Text
74 lines
2.3 KiB
Text
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GstController:
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==============
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Implementation:
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---------------
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Ideas and plans:
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- Deprecate control-rate property and add a control-period property
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that does the same and is named appropiately. Damn confusing names.
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- gst_object_suggest_next_sync() will not be used at all anymore.
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Note this in the docs and explain correct usage in elements.
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- Optimize get_value_array() functions to not just call get() but be
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a bit more intelligent.
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- Optimize trigger interpolator's get_value_array() to set trigger if
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a requested value's timestamp is before the trigger timestamp and
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this timestamp + sample period is after the trigger timestamp.
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- Get tempo interface in base (or core?) and have it modify the
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control rate to get expected results.
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- ? Let get_value_array() sample the values with control-period if
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the given sample_interval is zero ?
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Usage in elements:
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------------------
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- In the beginning of the processing loop call
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gst_object_sync_values() with the current timestamp.
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- Convert the controller's control-period property into frames/samples
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and request values sampled with control-period to apply one value to
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each control-period frames/samples.
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- Update controlled GObject properties with the last values, i.e.
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call gst_object_sync_values() with the end timestamp.
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- ! The user has to choose a good control-period to prevent two trigger
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timestamps separated by less than control-period nanoseconds.
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code:
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FIXME: can this be simplified? bugs in corner cases?
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[...]
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GstController ctrl = gst_object_get_controller (self);
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GstValueArray prop1;
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prop1.property_name = "prop1";
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if (ctrl) {
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gst_controller_sync_values (ctrl, GST_BUFFER_TIMESTAMP);
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samples_per_period = control-period / sample-rate;
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nvalues = num_samples / samples_per_period;
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prop1.nbsamples = nvalues;
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prop1.sample_interval = control-period;
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prop1.values = g_new (type, nvalues);
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gst_controller_get_value_array (ctrl, GST_BUFFER_TIMESTAMP, &prop1);
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} else {
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prop1.values = &self->prop1;
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samples_per_period = num_samples;
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}
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[...]
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for (i = 0; i < num_samples; i++) {
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prop1_val = prop1.values[i / samples_per_period];
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process();
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}
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[...]
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if (ctrl) {
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gst_controller_sync_values (ctrl, GST_BUFFER_TIMESTAMP + GST_BUFFER_DURATION);
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g_free (prop1.values);
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}
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