sink-input: Change move logic

The introduction of the history queue makes it possible to implement moving
of streams without involving the implementer. Instead of dropping all data
from the render memblockq and requesting the implementer to rewrite the
data, the render memblockq is now reconstructed from the history queue.

Additionally, the render queue will be filled with silence matching the
amount of audio that is left playing on the old sink to avoid playing
the same audio twice.

This patch slightly breaks moving for virtual sinks because they do not
yet include the resampler delay in their latency reports. This will be
fixed in a different patch set.

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/120>

src/pulsecore/sink-input.h

@@ -231,6 +231,9 @@ struct pa_sink_input {
      * mute status changes. Called from main context */
     void (*mute_changed)(pa_sink_input *i); /* may be NULL */
 
+    /* Used to store the rewind amount of the origin sink during a move */
+    size_t origin_rewind_bytes;    /* In sink input sample spec */
+
     struct {
         pa_sink_input_state_t state;
 
@@ -261,6 +264,12 @@ struct pa_sink_input {
         /* The requested latency for the sink */
         pa_usec_t requested_sink_latency;
 
+        /* Variables used during move */
+        pa_usec_t move_start_time;
+        pa_usec_t origin_sink_latency;
+        size_t resampler_delay_frames;
+        bool dont_rewrite;
+
         pa_hashmap *direct_outputs;
     } thread_info;
 
@@ -365,7 +374,7 @@ void pa_sink_input_request_rewind(pa_sink_input *i, size_t nbytes, bool rewrite,
 void pa_sink_input_cork(pa_sink_input *i, bool b);
 
 int pa_sink_input_set_rate(pa_sink_input *i, uint32_t rate);
-int pa_sink_input_update_resampler(pa_sink_input *i);
+int pa_sink_input_update_resampler(pa_sink_input *i, bool flush_history);
 
 /* This returns the sink's fields converted into out sample type */
 size_t pa_sink_input_get_max_rewind(pa_sink_input *i);