Hd-rum-translator: decompress only if transcoding

The rationale is that hd-rum-translator can be used as a packet
reflector as well, in which case it is capable process also different
packet types than video. In this case, if we do not require transcoding
ports, just disable additional video processing. This has also advantage
for video, if we use only packet reflector - no video decompression is
done and thus it reduces resourcees usage.

src/hd-rum-translator/hd-rum-decompress.cpp

@@ -264,3 +264,17 @@ void hd_rum_decompress_append_port(void *state, void *recompress_state)
         s->frame_consumed_cv.wait(l, [s]{ return s->received_frame.size() == 0; });
 }
 
+int hd_rum_decompress_get_num_active_ports(void *state)
+{
+        struct state_transcoder_decompress *s = (struct state_transcoder_decompress *) state;
+
+        int ret = 0;
+        for (auto && port : s->output_ports) {
+                if (port.active) {
+                        ret += 1;
+                }
+        }
+
+        return ret;
+}
+

src/hd-rum-translator/hd-rum-decompress.h

@@ -10,6 +10,7 @@ void hd_rum_decompress_done(void *state);
 void hd_rum_decompress_set_active(void *decompress_state, void *recompress_state, bool active);
 void hd_rum_decompress_remove_port(void *decompress_state, int index);
 void hd_rum_decompress_append_port(void *decompress_state, void *recompress_state);
+int hd_rum_decompress_get_num_active_ports(void *decompress_state);
 
 #ifdef __cplusplus
 }

src/hd-rum-translator/hd-rum-translator.cpp

@@ -326,9 +326,11 @@ static void *writer(void *arg)
                 }
             }
 
-            ssize_t ret = hd_rum_decompress_write(s->decompress, s->qhead->buf, s->qhead->size);
-            if (ret < 0) {
-                perror("hd_rum_decompress_write");
+            if (hd_rum_decompress_get_num_active_ports(s->decompress) > 0) {
+                ssize_t ret = hd_rum_decompress_write(s->decompress, s->qhead->buf, s->qhead->size);
+                if (ret < 0) {
+                    perror("hd_rum_decompress_write");
+                }
             }
 
             s->qhead = s->qhead->next;