vdisp/decklink: allow setting video connection

Usually not needed but needed when needing Composite output instead of
Component, because it is using the same wire as Y of component.

src/blackmagic_common.cpp

@@ -606,6 +606,7 @@ static const struct {
         BMDFCC(bmdDeckLinkConfigSMPTELevelAOutput),
         BMDFCC(bmdDeckLinkConfigVideoInputConnection),
         BMDFCC(bmdDeckLinkConfigVideoInputConversionMode),
+        BMDFCC(bmdDeckLinkConfigVideoOutputConnection),
         BMDFCC(bmdDeckLinkConfigVideoOutputConversionMode),
         BMDFCC(bmdDeckLinkConfigVideoOutputIdleOperation),
 };
@@ -939,8 +940,12 @@ bool bmd_option::device_write(IDeckLinkConfiguration *deckLinkConfiguration, BMD
                         return true;
         }
         ostringstream value_oss;
-        if (opt == bmdDeckLinkConfigVideoInputConnection && get_connection_string_map().find((BMDVideoConnection) get_int()) != get_connection_string_map().end()) {
-                value_oss << get_connection_string_map().at((BMDVideoConnection) get_int());
+        if ((opt == bmdDeckLinkConfigVideoInputConnection ||
+             opt == bmdDeckLinkConfigVideoOutputConnection) &&
+            get_connection_string_map().find((BMDVideoConnection) get_int()) !=
+                get_connection_string_map().end()) {
+                value_oss << get_connection_string_map().at(
+                    (BMDVideoConnection) get_int());
         } else {
                 value_oss << *this;
         }
@@ -1298,6 +1303,17 @@ print_bmd_connections(IDeckLinkProfileAttributes *deckLinkAttributes,
         col() << "\n";
 }
 
+BMDVideoConnection
+bmd_get_connection_by_name(const char *connection)
+{
+        for (auto const &it : get_connection_string_map()) {
+                if (strcasecmp(connection, it.second.c_str()) == 0) {
+                        return it.first;
+                }
+        }
+        return bmdVideoConnectionUnspecified;
+}
+
 /*   ____            _    _     _       _     ____  _        _             
  *  |  _ \  ___  ___| | _| |   (_)_ __ | | __/ ___|| |_ __ _| |_ _   _ ___ 
  *  | | | |/ _ \/ __| |/ / |   | | '_ \| |/ /\___ \| __/ _` | __| | | / __|

src/blackmagic_common.hpp

@@ -181,6 +181,7 @@ void print_bmd_attribute(IDeckLinkProfileAttributes *deckLinkAttributes,
 void print_bmd_connections(IDeckLinkProfileAttributes *deckLinkAttributes,
                            BMDDeckLinkAttributeID      id,
                            const char                 *module_prefix);
+BMDVideoConnection bmd_get_connection_by_name(const char *connection);
 
 /**
  * @details parameters:

src/video_capture/decklink.cpp

@@ -732,15 +732,13 @@ static bool parse_option(struct vidcap_decklink_state *s, const char *opt)
                 }
         } else if (IS_KEY_PREFIX(opt, "connection")) {
                 const char *connection = strchr(opt, '=') + 1;
-                for (auto const & it : get_connection_string_map()) {
-                        if (strcasecmp(connection, it.second.c_str()) == 0) {
-                                s->device_options[bmdDeckLinkConfigVideoInputConnection] = bmd_option((int64_t) it.first);
-                        }
-                }
-                if (s->device_options.find(bmdDeckLinkConfigVideoInputConnection) == s->device_options.end()) {
-                        log_msg(LOG_LEVEL_ERROR, MOD_NAME "Unrecognized connection %s.\n", connection);
+                auto        bmd_conn   = bmd_get_connection_by_name(connection);
+                if (bmd_conn == bmdVideoConnectionUnspecified) {
+                        MSG(ERROR, "Unrecognized connection %s.\n", connection);
                         return false;
                 }
+                s->device_options[bmdDeckLinkConfigVideoInputConnection] =
+                    bmd_option((int64_t) bmd_conn);
         } else if(strncasecmp(opt, "audio_level=",
                                 strlen("audio_level=")) == 0) {
                 s->device_options[bmdDeckLinkConfigAnalogAudioConsumerLevels] =

src/video_display/decklink.cpp

@@ -618,6 +618,7 @@ show_help(bool full, const char *query_prop_fcc = nullptr)
                 col() << SBOLD("\tUse1080PsF[=true|false|keep]") << " flag sets use of PsF on output instead of progressive (default is false)\n";
                 col() << SBOLD("\tprofile=<P>") << "\tuse desired device profile:\n";
                 print_bmd_device_profiles("\t\t");
+                col() << SBOLD("\tconnection=<conn>") << " set output video connection (usually unneeded)\n";
                 col() << SBOLD("\tmaxresample=<N>") << " maximum amount the resample delta can be when scaling is applied. Measured in Hz\n";
                 col() << SBOLD("\tminresample=<N>") << " minimum amount the resample delta can be when scaling is applied. Measured in Hz\n";
                 col() << SBOLD("\ttargetbuffer=<N>") << " target amount of samples to have in the buffer (per channel)\n";
@@ -1302,6 +1303,17 @@ static bool settings_init(struct state_decklink *s, const char *fmt,
                                         return false;
                                 }
                         }
+                } else if (IS_KEY_PREFIX(ptr, "connection")) {
+                        const char *connection = strchr(ptr, '=') + 1;
+                        auto bmd_conn = bmd_get_connection_by_name(connection);
+                        if (bmd_conn == bmdVideoConnectionUnspecified) {
+                                MSG(ERROR, "Unrecognized connection %s.\n",
+                                    connection);
+                                return false;
+                        }
+                        s->device_options
+                            [bmdDeckLinkConfigVideoOutputConnection] =
+                            bmd_option((int64_t) bmd_conn);
                 } else if (strstr(ptr, "keep-settings") == ptr) {
                         s->keep_device_defaults = true;
                 } else if (strstr(ptr, "drift_fix") == ptr) {