]> git.sesse.net Git - nageru/blobdiff - nageru/scene.cpp
Collapse all the 10-bit flags.
[nageru] / nageru / scene.cpp
index 70bccbe1a73f11d31424654a630ef2d1600e21db..11a3d2171de11851f89bf4e3f663a2f7b51780f6 100644 (file)
@@ -18,7 +18,7 @@ extern "C" {
 using namespace movit;
 using namespace std;
 
-bool display(Block *block, lua_State *L, int idx);
+static bool display(Block *block, lua_State *L, int idx);
 
 EffectType current_type(const Block *block)
 {
@@ -35,6 +35,16 @@ int find_index_of(const Block *block, EffectType val)
        return -1;
 }
 
+string get_declaration_point(lua_State *L)
+{
+       lua_Debug ar;
+       lua_getstack(L, 1, &ar);
+       lua_getinfo(L, "nSl", &ar);
+       char buf[256];
+       snprintf(buf, sizeof(buf), "%s:%d", ar.source, ar.currentline);
+       return buf;
+}
+
 Scene::Scene(Theme *theme, float aspect_nom, float aspect_denom)
        : theme(theme), aspect_nom(aspect_nom), aspect_denom(aspect_denom), resource_pool(theme->get_resource_pool()) {}
 
@@ -87,19 +97,42 @@ bitset<256> Scene::find_disabled_blocks(size_t chain_idx) const
        do {
                find_disabled_blocks(chain_idx, blocks.size() - 1, /*currently_disabled=*/false, &ret);
                prev = ret;
+
+               // Propagate DISABLE_IF_OTHER_DISABLED constraints (we can always do this).
                for (Block *block : blocks) {
+                       if (ret.test(block->idx)) continue;  // Already disabled.
+
                        EffectType chosen_type = block->alternatives[block->chosen_alternative(chain_idx)]->effect_type;
-                       if (ret.test(block->idx) || chosen_type == IDENTITY_EFFECT) continue;  // Already disabled.
+                       if (chosen_type == IDENTITY_EFFECT) {
+                               ret.set(block->idx);
+                               continue;
+                       }
 
-                       for (Block::Index disabler_idx : block->disablers) {
-                               Block *disabler = blocks[disabler_idx];
-                               EffectType chosen_type = disabler->alternatives[disabler->chosen_alternative(chain_idx)]->effect_type;
-                               if (ret.test(disabler->idx) || chosen_type == IDENTITY_EFFECT) {
+                       for (const Block::Disabler &disabler : block->disablers) {
+                               Block *other = blocks[disabler.block_idx];
+                               EffectType chosen_type = other->alternatives[other->chosen_alternative(chain_idx)]->effect_type;
+                               bool other_disabled = ret.test(disabler.block_idx) || chosen_type == IDENTITY_EFFECT;
+                               if (other_disabled && disabler.condition == Block::Disabler::DISABLE_IF_OTHER_DISABLED) {
                                        ret.set(block->idx);
                                        break;
                                }
                        }
                }
+
+               // We cannot propagate DISABLE_IF_OTHER_ENABLED in all cases;
+               // the problem is that if A is disabled if B is enabled,
+               // then we cannot disable A unless we actually know for sure
+               // that B _is_ enabled. (E.g., imagine that B is disabled
+               // if C is enabled -- we couldn't disable A before we knew if
+               // C was enabled or not!)
+               //
+               // We could probably fix a fair amount of these, but the
+               // primary use case for DISABLE_IF_OTHER_ENABLED is really
+               // mutual exclusion; A must be disabled if B is enabled
+               // _and_ vice versa. These loops cannot be automatically
+               // resolved; it would depend on what A and B is. Thus,
+               // we simply declare this kind of constraint to be a promise
+               // from the user, not something that we'll solve for them.
        } while (prev != ret);
        return ret;
 }
@@ -127,15 +160,31 @@ void Scene::find_disabled_blocks(size_t chain_idx, size_t block_idx, bool curren
 bool Scene::is_noncanonical_chain(size_t chain_idx) const
 {
        bitset<256> disabled = find_disabled_blocks(chain_idx);
-       if (disabled.none()) {
-               return false;
-       }
        assert(blocks.size() < 256);
        for (size_t block_idx = 0; block_idx < blocks.size(); ++block_idx) {
                Block *block = blocks[block_idx];
                if (disabled.test(block_idx) && block->chosen_alternative(chain_idx) != block->canonical_alternative) {
                        return true;
                }
+
+               // Test if we're supposed to be disabled by some other block being enabled;
+               // the disabled bit mask does not fully capture this.
+               if (!disabled.test(block_idx)) {
+                       for (const Block::Disabler &disabler : block->disablers) {
+                               if (disabler.condition == Block::Disabler::DISABLE_IF_OTHER_ENABLED &&
+                                   !disabled.test(disabler.block_idx)) {
+                                       return true;
+                               }
+                       }
+
+                       // Auto white balance is always disabled for image inputs.
+                       if (block->white_balance_controller_block != nullptr) {
+                               const Block *input = block->white_balance_controller_block;
+                               if (input->alternatives[input->chosen_alternative(chain_idx)]->effect_type == IMAGE_INPUT) {
+                                       return true;
+                               }
+                       }
+               }
        }
        return false;
 }
@@ -146,6 +195,7 @@ int Scene::add_input(lua_State* L)
        Scene *scene = (Scene *)luaL_checkudata(L, 1, "Scene");
 
        Block *block = new Block;
+       block->declaration_point = get_declaration_point(L);
        block->idx = scene->blocks.size();
        if (lua_gettop(L) == 1) {
                // No parameter given, so a flexible input.
@@ -159,6 +209,11 @@ int Scene::add_input(lua_State* L)
                if (lua_isnumber(L, 2)) {
                        block->alternatives.emplace_back(new EffectBlueprint(LIVE_INPUT_YCBCR));
                        block->alternatives.emplace_back(new EffectBlueprint(LIVE_INPUT_YCBCR_WITH_DEINTERLACE));
+#ifdef HAVE_SRT
+                       if (global_flags.srt_port >= 0) {
+                               block->alternatives.emplace_back(new EffectBlueprint(LIVE_INPUT_YCBCR_PLANAR));
+                       }
+#endif
 #ifdef HAVE_CEF
                } else if (luaL_testudata(L, 2, "HTMLInput")) {
                        block->alternatives.emplace_back(new EffectBlueprint(LIVE_INPUT_BGRA));
@@ -185,34 +240,35 @@ int Scene::add_input(lua_State* L)
        return wrap_lua_existing_object_nonowned<Block>(L, "Block", block);
 }
 
-void Scene::find_inputs_for_block(lua_State *L, Scene *scene, Block *block)
+Block *Scene::find_block_from_arg(lua_State *L, Scene *scene, int idx)
 {
-       if (lua_gettop(L) == 2) {
+       if (luaL_testudata(L, idx, "Block")) {
+               return *(Block **)luaL_checkudata(L, idx, "Block");
+       } else {
+               EffectBlueprint *blueprint = *(EffectBlueprint **)luaL_checkudata(L, idx, "EffectBlueprint");
+
+               // Search through all the blocks to figure out which one contains this effect.
+               for (Block *block : scene->blocks) {
+                       if (find(block->alternatives.begin(), block->alternatives.end(), blueprint) != block->alternatives.end()) {
+                               return block;
+                       }
+               }
+               luaL_error(L, "Input effect in parameter #%d has not been added to this scene", idx - 1);
+               return nullptr;  // Dead code.
+       }
+}
+
+void Scene::find_inputs_for_block(lua_State *L, Scene *scene, Block *block, int first_input_idx)
+{
+       if (lua_gettop(L) == first_input_idx - 1) {
                // Implicitly the last added effect.
                assert(!scene->blocks.empty());
                block->inputs.push_back(scene->blocks.size() - 1);
                return;
        }
 
-       for (int idx = 3; idx <= lua_gettop(L); ++idx) {
-               Block *input_block = nullptr;
-               if (luaL_testudata(L, idx, "Block")) {
-                       input_block = *(Block **)luaL_checkudata(L, idx, "Block");
-               } else {
-                       EffectBlueprint *blueprint = *(EffectBlueprint **)luaL_checkudata(L, idx, "EffectBlueprint");
-
-                       // Search through all the blocks to figure out which one contains this effect.
-                       for (Block *block : scene->blocks) {
-                               if (find(block->alternatives.begin(), block->alternatives.end(), blueprint) != block->alternatives.end()) {
-                                       input_block = block;
-                                       break;
-                               }
-                       }
-                       if (input_block == nullptr) {
-                               luaL_error(L, "Input effect in parameter #%d has not been added to this scene", idx - 1);
-                       }
-               }
-               block->inputs.push_back(input_block->idx);
+       for (int idx = first_input_idx; idx <= lua_gettop(L); ++idx) {
+               block->inputs.push_back(find_block_from_arg(L, scene, idx)->idx);
        }
 }
 
@@ -222,6 +278,7 @@ int Scene::add_effect(lua_State* L)
        Scene *scene = (Scene *)luaL_checkudata(L, 1, "Scene");
 
        Block *block = new Block;
+       block->declaration_point = get_declaration_point(L);
        block->idx = scene->blocks.size();
 
        if (lua_istable(L, 2)) {
@@ -258,6 +315,7 @@ int Scene::add_optional_effect(lua_State* L)
        Scene *scene = (Scene *)luaL_checkudata(L, 1, "Scene");
 
        Block *block = new Block;
+       block->declaration_point = get_declaration_point(L);
        block->idx = scene->blocks.size();
 
        EffectBlueprint *blueprint = *(EffectBlueprint **)luaL_checkudata(L, 2, "EffectBlueprint");
@@ -274,6 +332,65 @@ int Scene::add_optional_effect(lua_State* L)
        return wrap_lua_existing_object_nonowned<Block>(L, "Block", block);
 }
 
+const Block *Scene::find_root_input_block(lua_State *L, const Block *block)
+{
+       if (block->is_input) {
+               assert(block->inputs.size() == 0);
+               return block;
+       }
+
+       const Block *ret = nullptr;
+       for (size_t input_idx : block->inputs) {
+               const Block *parent = find_root_input_block(L, blocks[input_idx]);
+               if (parent != nullptr) {
+                       if (ret != nullptr) {
+                               luaL_error(L, "add_white_balance() was connected to more than one input");
+                       }
+                       ret = parent;
+               }
+       }
+       return ret;
+}
+
+int Scene::add_white_balance(lua_State* L)
+{
+       assert(lua_gettop(L) >= 1);
+       Scene *scene = (Scene *)luaL_checkudata(L, 1, "Scene");
+
+       Block *block = new Block;
+       block->declaration_point = get_declaration_point(L);
+       block->idx = scene->blocks.size();
+
+       block->alternatives.push_back(new EffectBlueprint(WHITE_BALANCE_EFFECT));
+       block->alternatives.push_back(new EffectBlueprint(IDENTITY_EFFECT));
+
+       block->canonical_alternative = 1;
+
+       if (lua_gettop(L) == 1) {
+               // The last added effect is implicitly both the input and gives the white balance controller.
+               assert(!scene->blocks.empty());
+               block->inputs.push_back(scene->blocks.size() - 1);
+               block->white_balance_controller_block = scene->find_root_input_block(L, block);
+       } else if (lua_gettop(L) == 2) {
+               // The given effect is both the input and the white balance controller.
+               block->inputs.push_back(find_block_from_arg(L, scene, 2)->idx);
+               block->white_balance_controller_block = scene->find_root_input_block(L, block);
+       } else if (lua_gettop(L) == 3) {
+               // We have explicit input and white balance controller.
+               block->inputs.push_back(find_block_from_arg(L, scene, 2)->idx);
+               block->white_balance_controller_block = find_block_from_arg(L, scene, 3);
+       } else {
+               luaL_error(L, "add_white_balance([input], [white_balance_controller]) takes zero, one or two arguments");
+       }
+       if (block->white_balance_controller_block == nullptr || !block->white_balance_controller_block->is_input) {
+               luaL_error(L, "add_white_balance() does not get its white balance from an input");
+       }
+
+       scene->blocks.push_back(block);
+
+       return wrap_lua_existing_object_nonowned<Block>(L, "Block", block);
+}
+
 Effect *Scene::instantiate_effects(const Block *block, size_t chain_idx, Scene::Instantiation *instantiation)
 {
        // Find the chosen alternative for this block in this instance.
@@ -305,7 +422,7 @@ Effect *Scene::instantiate_effects(const Block *block, size_t chain_idx, Scene::
                        pixel_format = bmusb::PixelFormat_8BitBGRA;
                } else if (chosen_type == LIVE_INPUT_YCBCR_PLANAR) {
                        pixel_format = bmusb::PixelFormat_8BitYCbCrPlanar;
-               } else if (global_flags.ten_bit_input) {
+               } else if (global_flags.bit_depth > 8) {
                        pixel_format = bmusb::PixelFormat_10BitYCbCr;
                } else {
                        pixel_format = bmusb::PixelFormat_8BitYCbCr;
@@ -383,6 +500,24 @@ int Scene::finalize(lua_State* L)
        return 0;
 }
 
+int find_card_to_connect(Theme *theme, lua_State *L, const Block *block)
+{
+       if (block->signal_type_to_connect == Block::CONNECT_SIGNAL) {
+               return theme->map_signal_to_card(block->signal_to_connect);
+#ifdef HAVE_CEF
+       } else if (block->signal_type_to_connect == Block::CONNECT_CEF) {
+               return block->cef_to_connect->get_card_index();
+#endif
+       } else if (block->signal_type_to_connect == Block::CONNECT_VIDEO) {
+               return block->video_to_connect->get_card_index();
+       } else if (block->signal_type_to_connect == Block::CONNECT_NONE) {
+               luaL_error(L, "An input in a scene was not connected to anything (forgot to call display())");
+       } else {
+               assert(false);
+       }
+       return -1;
+}
+
 std::pair<movit::EffectChain *, std::function<void()>>
 Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &input_state)
 {
@@ -391,13 +526,54 @@ Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &inp
        InputStateInfo info(input_state);
        for (Block *block : blocks) {
                if (block->is_input && block->signal_type_to_connect == Block::CONNECT_SIGNAL) {
-                       EffectType chosen_type = current_type(block);
-                       assert(chosen_type == LIVE_INPUT_YCBCR || chosen_type == LIVE_INPUT_YCBCR_WITH_DEINTERLACE);
-                       if (info.last_interlaced[block->signal_to_connect]) {
+                       int card_index = theme->map_signal_to_card(block->signal_to_connect);
+                       if (info.last_interlaced[card_index]) {
+                               assert(info.last_pixel_format[card_index] == bmusb::PixelFormat_8BitYCbCr ||
+                                      info.last_pixel_format[card_index] == bmusb::PixelFormat_10BitYCbCr);
                                block->currently_chosen_alternative = find_index_of(block, LIVE_INPUT_YCBCR_WITH_DEINTERLACE);
+                       } else if (info.last_pixel_format[card_index] == bmusb::PixelFormat_8BitYCbCrPlanar) {
+                               block->currently_chosen_alternative = find_index_of(block, LIVE_INPUT_YCBCR_PLANAR);
+                       } else if (info.last_pixel_format[card_index] == bmusb::PixelFormat_8BitBGRA) {
+                               block->currently_chosen_alternative = find_index_of(block, LIVE_INPUT_BGRA);
                        } else {
                                block->currently_chosen_alternative = find_index_of(block, LIVE_INPUT_YCBCR);
                        }
+                       if (block->currently_chosen_alternative == -1) {
+                               fprintf(stderr, "ERROR: Input connected to a video card pixel format that it was not ready for.\n");
+                               abort();
+                       }
+               }
+       }
+
+       // Find all auto white balance blocks, turn on and off the effect as needed,
+       // and fetch the actual white balance set (it is stored in Theme).
+       map<Block *, array<float, 3>> white_balance;
+       for (size_t block_idx = 0; block_idx < blocks.size(); ++block_idx) {
+               Block *block = blocks[block_idx];
+               const Block *input = block->white_balance_controller_block;
+               if (input == nullptr) {
+                       continue;  // Not an auto white balance block.
+               }
+
+               EffectType chosen_type = current_type(input);
+               if (chosen_type == IMAGE_INPUT) {
+                       // Image inputs never get white balance applied.
+                       block->currently_chosen_alternative = find_index_of(block, IDENTITY_EFFECT);
+                       continue;
+               }
+
+               assert(chosen_type == LIVE_INPUT_YCBCR ||
+                      chosen_type == LIVE_INPUT_YCBCR_WITH_DEINTERLACE ||
+                      chosen_type == LIVE_INPUT_YCBCR_PLANAR ||
+                      chosen_type == LIVE_INPUT_BGRA);
+               int card_idx = find_card_to_connect(theme, L, input);
+               RGBTriplet wb = theme->get_white_balance_for_card(card_idx);
+               if (fabs(wb.r - 1.0) < 1e-3 && fabs(wb.g - 1.0) < 1e-3 && fabs(wb.b - 1.0) < 1e-3) {
+                       // Neutral white balance.
+                       block->currently_chosen_alternative = find_index_of(block, IDENTITY_EFFECT);
+               } else {
+                       block->currently_chosen_alternative = find_index_of(block, WHITE_BALANCE_EFFECT);
+                       white_balance.emplace(block, array<float, 3>{ wb.r, wb.g, wb.b });
                }
        }
 
@@ -407,10 +583,27 @@ Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &inp
        // the Lua code later.
        bool is_main_chain = (num == 0);
        size_t chain_idx = compute_chain_number(is_main_chain);
+       if (is_noncanonical_chain(chain_idx)) {
+               // This should be due to promise_to_disable_if_enabled(). Find out what
+               // happened, to give the user some help.
+               bitset<256> disabled = find_disabled_blocks(chain_idx);
+               for (size_t block_idx = 0; block_idx < blocks.size(); ++block_idx) {
+                       Block *block = blocks[block_idx];
+                       if (disabled.test(block_idx)) continue;
+                       for (const Block::Disabler &disabler : block->disablers) {
+                               if (disabler.condition == Block::Disabler::DISABLE_IF_OTHER_ENABLED &&
+                                   !disabled.test(disabler.block_idx)) {
+                                       fprintf(stderr, "Promise declared at %s violated.\n", disabler.declaration_point.c_str());
+                                       abort();
+                               }
+                       }
+               }
+               assert(false);  // Something else happened, seemingly.
+       }
        const Scene::Instantiation &instantiation = chains[chain_idx];
        EffectChain *effect_chain = instantiation.chain.get();
 
-       map<LiveInputWrapper *, int> signals_to_connect;
+       map<LiveInputWrapper *, int> cards_to_connect;
        map<ImageInput *, string> images_to_select;
        map<pair<Effect *, string>, int> int_to_set;
        map<pair<Effect *, string>, float> float_to_set;
@@ -419,24 +612,12 @@ Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &inp
        for (const auto &index_and_input : instantiation.inputs) {
                Block *block = blocks[index_and_input.first];
                EffectType chosen_type = current_type(block);
-               LiveInputWrapper *input = index_and_input.second;
                if (chosen_type == LIVE_INPUT_YCBCR ||
                    chosen_type == LIVE_INPUT_YCBCR_WITH_DEINTERLACE ||
                    chosen_type == LIVE_INPUT_YCBCR_PLANAR ||
                    chosen_type == LIVE_INPUT_BGRA) {
-                       if (block->signal_type_to_connect == Block::CONNECT_SIGNAL) {
-                               signals_to_connect.emplace(input, block->signal_to_connect);
-#ifdef HAVE_CEF
-                       } else if (block->signal_type_to_connect == Block::CONNECT_CEF) {
-                               signals_to_connect.emplace(input, block->cef_to_connect->get_card_index());
-#endif
-                       } else if (block->signal_type_to_connect == Block::CONNECT_VIDEO) {
-                               signals_to_connect.emplace(input, block->video_to_connect->get_card_index());
-                       } else if (block->signal_type_to_connect == Block::CONNECT_NONE) {
-                               luaL_error(L, "An input in a scene was not connected to anything (forgot to call display())");
-                       } else {
-                               assert(false);
-                       }
+                       LiveInputWrapper *input = index_and_input.second;
+                       cards_to_connect.emplace(input, find_card_to_connect(theme, L, block));
                }
        }
        for (const auto &index_and_input : instantiation.image_inputs) {
@@ -450,14 +631,28 @@ Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &inp
                Block *block = blocks[index_and_effect.first];
                Effect *effect = index_and_effect.second;
 
+               bool missing_width = (current_type(block) == RESIZE_EFFECT ||
+                       current_type(block) == RESAMPLE_EFFECT ||
+                       current_type(block) == PADDING_EFFECT);
+               bool missing_height = missing_width;
+
                // Get the effects currently set on the block.
                if (current_type(block) != IDENTITY_EFFECT) {  // Ignore settings on optional effects.
+                       if (block->int_parameters.count("width") && block->int_parameters["width"] > 0) {
+                               missing_width = false;
+                       }
+                       if (block->int_parameters.count("height") && block->int_parameters["height"] > 0) {
+                               missing_height = false;
+                       }
                        for (const auto &key_and_tuple : block->int_parameters) {
                                int_to_set.emplace(make_pair(effect, key_and_tuple.first), key_and_tuple.second);
                        }
                        for (const auto &key_and_tuple : block->float_parameters) {
                                float_to_set.emplace(make_pair(effect, key_and_tuple.first), key_and_tuple.second);
                        }
+                       if (white_balance.count(block)) {
+                               vec3_to_set.emplace(make_pair(effect, "neutral_color"), white_balance[block]);
+                       }
                        for (const auto &key_and_tuple : block->vec3_parameters) {
                                vec3_to_set.emplace(make_pair(effect, key_and_tuple.first), key_and_tuple.second);
                        }
@@ -470,6 +665,12 @@ Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &inp
                // so they are set afterwards.
                if (!block->alternatives.empty()) {
                        EffectBlueprint *blueprint = block->alternatives[block->currently_chosen_alternative];
+                       if (blueprint->int_parameters.count("width") && blueprint->int_parameters["width"] > 0) {
+                               missing_width = false;
+                       }
+                       if (blueprint->int_parameters.count("height") && blueprint->int_parameters["height"] > 0) {
+                               missing_height = false;
+                       }
                        for (const auto &key_and_tuple : blueprint->int_parameters) {
                                int_to_set[make_pair(effect, key_and_tuple.first)] = key_and_tuple.second;
                        }
@@ -483,17 +684,25 @@ Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &inp
                                vec4_to_set[make_pair(effect, key_and_tuple.first)] = key_and_tuple.second;
                        }
                }
+
+               if (missing_width || missing_height) {
+                       fprintf(stderr, "WARNING: Unset or nonpositive width/height for effect declared at %s "
+                               "when getting scene for signal %u; setting to 1x1 to avoid crash.\n",
+                               block->declaration_point.c_str(), num);
+                       int_to_set[make_pair(effect, "width")] = 1;
+                       int_to_set[make_pair(effect, "height")] = 1;
+               }
        }
 
        lua_pop(L, 1);
 
-       auto setup_chain = [L, theme, signals_to_connect, images_to_select, int_to_set, float_to_set, vec3_to_set, vec4_to_set, input_state]{
+       auto setup_chain = [L, theme, cards_to_connect, images_to_select, int_to_set, float_to_set, vec3_to_set, vec4_to_set, input_state]{
                lock_guard<mutex> lock(theme->m);
 
-               // Set up state, including connecting signals.
-               for (const auto &input_and_signal : signals_to_connect) {
-                       LiveInputWrapper *input = input_and_signal.first;
-                       input->connect_signal_raw(input_and_signal.second, input_state);
+               // Set up state, including connecting cards.
+               for (const auto &input_and_card : cards_to_connect) {
+                       LiveInputWrapper *input = input_and_card.first;
+                       input->connect_card(input_and_card.second, input_state);
                }
                for (const auto &input_and_filename : images_to_select) {
                        input_and_filename.first->switch_image(input_and_filename.second);
@@ -539,10 +748,9 @@ Scene::get_chain(Theme *theme, lua_State *L, unsigned num, const InputState &inp
 bool display(Block *block, lua_State *L, int idx)
 {
        if (lua_isnumber(L, idx)) {
-               Theme *theme = get_theme_updata(L);
                int signal_idx = luaL_checknumber(L, idx);
                block->signal_type_to_connect = Block::CONNECT_SIGNAL;
-               block->signal_to_connect = theme->map_signal(signal_idx);
+               block->signal_to_connect = signal_idx;
                block->currently_chosen_alternative = find_index_of(block, LIVE_INPUT_YCBCR);  // Will be changed to deinterlaced at get_chain() time if needed.
                return true;
 #ifdef HAVE_CEF
@@ -679,7 +887,29 @@ int Block_always_disable_if_disabled(lua_State *L)
                luaL_error(L, "always_disable_if_disabled() with an argument that didn't have an IdentityEffect fallback (try add_optional_effect())");
        }
 
-       block->disablers.push_back(disabler_block->idx);
+       // The declaration point isn't actually used, but it's nice for completeness.
+       block->disablers.push_back(Block::Disabler{ disabler_block->idx, Block::Disabler::DISABLE_IF_OTHER_DISABLED, get_declaration_point(L) });
+
+       lua_pop(L, 2);
+       return 0;
+}
+
+int Block_promise_to_disable_if_enabled(lua_State *L)
+{
+       assert(lua_gettop(L) == 2);
+       Block *block = *(Block **)luaL_checkudata(L, 1, "Block");
+       Block *disabler_block = *(Block **)luaL_checkudata(L, 2, "Block");
+
+       int my_alternative = find_index_of(block, IDENTITY_EFFECT);
+       int their_alternative = find_index_of(disabler_block, IDENTITY_EFFECT);
+       if (my_alternative == -1) {
+               luaL_error(L, "promise_to_disable_if_enabled() called on something that didn't have an IdentityEffect fallback (try add_optional_effect())");
+       }
+       if (their_alternative == -1) {
+               luaL_error(L, "promise_to_disable_if_enabled() with an argument that didn't have an IdentityEffect fallback (try add_optional_effect())");
+       }
+
+       block->disablers.push_back(Block::Disabler{ disabler_block->idx, Block::Disabler::DISABLE_IF_OTHER_ENABLED, get_declaration_point(L) });
 
        lua_pop(L, 2);
        return 0;