lavfi: add helper functions and macros for activate.

libavfilter/avfilter.c

@@ -1668,6 +1668,26 @@ void ff_inlink_request_frame(AVFilterLink *link)
     ff_filter_set_ready(link->src, 100);
 }
 
+void ff_inlink_set_status(AVFilterLink *link, int status)
+{
+    if (link->status_out)
+        return;
+    link->frame_wanted_out = 0;
+    link->frame_blocked_in = 0;
+    ff_avfilter_link_set_out_status(link, status, AV_NOPTS_VALUE);
+    while (ff_framequeue_queued_frames(&link->fifo)) {
+           AVFrame *frame = ff_framequeue_take(&link->fifo);
+           av_frame_free(&frame);
+    }
+    if (!link->status_in)
+        link->status_in = status;
+}
+
+int ff_outlink_get_status(AVFilterLink *link)
+{
+    return link->status_in;
+}
+
 const AVClass *avfilter_get_class(void)
 {
     return &avfilter_class;

libavfilter/filters.h

@@ -140,6 +140,12 @@ int ff_inlink_acknowledge_status(AVFilterLink *link, int *rstatus, int64_t *rpts
  */
 void ff_inlink_request_frame(AVFilterLink *link);
 
+/**
+ * Set the status on an input link.
+ * Also discard all frames in the link's FIFO.
+ */
+void ff_inlink_set_status(AVFilterLink *link, int status);
+
 /**
  * Test if a frame is wanted on an output link.
  */
@@ -148,6 +154,11 @@ static inline int ff_outlink_frame_wanted(AVFilterLink *link)
     return link->frame_wanted_out;
 }
 
+/**
+ * Get the status on an output link.
+ */
+int ff_outlink_get_status(AVFilterLink *link);
+
 /**
  * Set the status field of a link from the source filter.
  * The pts should reflect the timestamp of the status change,
@@ -160,4 +171,71 @@ static inline void ff_outlink_set_status(AVFilterLink *link, int status, int64_t
     ff_avfilter_link_set_in_status(link, status, pts);
 }
 
+/**
+ * Forward the status on an output link to an input link.
+ * If the status is set, it will discard all queued frames and this macro
+ * will return immediately.
+ */
+#define FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink) do { \
+    int ret = ff_outlink_get_status(outlink); \
+    if (ret) { \
+        ff_inlink_set_status(inlink, ret); \
+        return 0; \
+    } \
+} while (0)
+
+/**
+ * Forward the status on an output link to all input links.
+ * If the status is set, it will discard all queued frames and this macro
+ * will return immediately.
+ */
+#define FF_FILTER_FORWARD_STATUS_BACK_ALL(outlink, filter) do { \
+    int ret = ff_outlink_get_status(outlink); \
+    if (ret) { \
+        unsigned i; \
+        for (i = 0; i < filter->nb_inputs; i++) \
+            ff_inlink_set_status(filter->inputs[i], ret); \
+        return 0; \
+    } \
+} while (0)
+
+/**
+ * Acknowledge the status on an input link and forward it to an output link.
+ * If the status is set, this macro will return immediately.
+ */
+#define FF_FILTER_FORWARD_STATUS(inlink, outlink) do { \
+    int status; \
+    int64_t pts; \
+    if (ff_inlink_acknowledge_status(inlink, &status, &pts)) { \
+        ff_outlink_set_status(outlink, status, pts); \
+        return 0; \
+    } \
+} while (0)
+
+/**
+ * Acknowledge the status on an input link and forward it to an output link.
+ * If the status is set, this macro will return immediately.
+ */
+#define FF_FILTER_FORWARD_STATUS_ALL(inlink, filter) do { \
+    int status; \
+    int64_t pts; \
+    if (ff_inlink_acknowledge_status(inlink, &status, &pts)) { \
+        unsigned i; \
+        for (i = 0; i < filter->nb_outputs; i++) \
+            ff_outlink_set_status(filter->outputs[i], status, pts); \
+        return 0; \
+    } \
+} while (0)
+
+/**
+ * Forward the frame_wanted_out flag from an output link to an input link.
+ * If the flag is set, this macro will return immediately.
+ */
+#define FF_FILTER_FORWARD_WANTED(outlink, inlink) do { \
+    if (ff_outlink_frame_wanted(outlink)) { \
+        ff_inlink_request_frame(inlink); \
+        return 0; \
+    } \
+} while (0)
+
 #endif /* AVFILTER_FILTERS_H */