unregister video decoder module when deactivated

Every video stream has its own decoder. So that when received new stream
(eg. sender restart), new decoder is created while the old is just
deactivated (display is removed and assigned to the newly created one).

But the decoder lives for some time (AFAIK removed after RTP timeout,
which is IIRC 30 sec). During the period, multiple decoders co-exist
under the same path "receiver.decoder". Since the keycontrol prints the
format obtained via control socket, almost certainly the message will be
delivered to the old (inactive) decoder with the old format.

As the solution we added module descturction when module is deactivated.
Also renamed the `video_decoder_remove_display()` to
`video_decoder_deactivate()` (2 things are done now).

Removed video_decoder_register_display() from external API - it would
not register the module again, so it cannot be used to revert the
_deactivate() call now. Currently not used, anyways.

Author: MartinPulec

src/rtp/video_decoders.cpp

@@ -188,6 +188,8 @@ static void *fec_thread(void *args);
 static void *decompress_thread(void *args);
 static void cleanup(struct state_video_decoder *decoder);
 static void decoder_process_message(struct module *);
+static bool  video_decoder_register_display(struct state_video_decoder *decoder,
+                                            struct display             *display);
 
 static int sum_map(map<int, int> const & m) {
         int ret = 0;
@@ -861,7 +863,9 @@ ADD_TO_PARAM("decoder-use-codec",
  * @param display new display to be registered
  * @return        whether registration was successful
  */
-bool video_decoder_register_display(struct state_video_decoder *decoder, struct display *display)
+static bool
+video_decoder_register_display(struct state_video_decoder *decoder,
+                               struct display             *display)
 {
         assert(display != NULL);
         assert(decoder->display == NULL);
@@ -936,14 +940,18 @@ bool video_decoder_register_display(struct state_video_decoder *decoder, struct
 }
 
 /**
- * @brief This removes display from current decoder.
+ * This removes display from current decoder and uninitializes module so that it
+ * won't respond on messages (newly created decoder should).
  *
  * From now on, no video frames will be decoded with current decoder.
- * @see decoder_register_display - the counterpart of this function
+ * video_decoder_register_display() used to re-enable decoder but it is not
+ * currently used and as this now also deactivates the module, this should be
+ * re-enabled as well.
  *
  * @param decoder decoder from which will the decoder be removed
  */
-void video_decoder_remove_display(struct state_video_decoder *decoder)
+void
+video_decoder_deactivate(struct state_video_decoder *decoder)
 {
         if (decoder->display) {
                 video_decoder_stop_threads(decoder);
@@ -954,6 +962,10 @@ void video_decoder_remove_display(struct state_video_decoder *decoder)
                 decoder->display = NULL;
                 memset(&decoder->display_desc, 0, sizeof(decoder->display_desc));
         }
+        if (decoder->mod.cls) {
+                module_done(&decoder->mod);
+                decoder->mod.cls = MODULE_CLASS_NONE;
+        }
 }
 
 static void cleanup(struct state_video_decoder *decoder)
@@ -987,7 +999,7 @@ void video_decoder_destroy(struct state_video_decoder *decoder)
                 decoder->dec_funcs->destroy(decoder->decrypt);
         }
 
-        video_decoder_remove_display(decoder);
+        video_decoder_deactivate(decoder);
 
         cleanup(decoder);
 

src/rtp/video_decoders.h

@@ -10,7 +10,7 @@
  */
 /*
  * Copyright (c) 2003 University of Southern California
- * Copyright (c) 2005-2013 CESNET z.s.p.o.
+ * Copyright (c) 2005-2026 CESNET, zájmové sdružení právnických osob
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, is permitted provided that the following conditions
@@ -71,8 +71,7 @@ int decode_video_frame(struct coded_data *received_data, void *decoder_data, str
 struct state_video_decoder *video_decoder_init(struct module *parent, enum video_mode,
                 struct display *display, const char *encryption);
 void video_decoder_destroy(struct state_video_decoder *decoder);
-bool video_decoder_register_display(struct state_video_decoder *decoder, struct display *display);
-void video_decoder_remove_display(struct state_video_decoder *decoder);
+void video_decoder_deactivate(struct state_video_decoder *decoder);
 bool parse_video_hdr(const uint32_t *hdr, struct video_desc *desc);
 
 /** @} */ // end of video_rtp_decoder

src/video_rxtx/ultragrid_rtp.cpp

@@ -270,9 +270,11 @@ void ultragrid_rtp_video_rxtx::remove_display_from_decoders() {
                 pdb_iter_t it;
                 struct pdb_e *cp = pdb_iter_init(m_rtp_common->participants, &it);
                 while (cp != NULL) {
-                        if(cp->decoder_state)
-                                video_decoder_remove_display(
-                                                ((struct vcodec_state*) cp->decoder_state)->decoder);
+                        if (cp->decoder_state) {
+                                video_decoder_deactivate(
+                                    ((struct vcodec_state *) cp->decoder_state)
+                                        ->decoder);
+                        }
                         cp = pdb_iter_next(&it);
                 }
                 pdb_iter_done(&it);