X-Git-Url: https://git.sesse.net/?p=nageru;a=blobdiff_plain;f=theme.lua;h=401cbd9b842d822d74d0fbbbd2f437e630e3e95e;hp=243b352670182c7bbd3c56dffe761bf32d5e268f;hb=4e3c52ba57c4552a969e71ccdefd9941ce8d6290;hpb=f245cb0d0453e0e8bd5c7d40720bd0a5b50454ee

diff --git a/theme.lua b/theme.lua
index 243b352..401cbd9 100644
--- a/theme.lua
+++ b/theme.lua
@@ -7,19 +7,21 @@
 -- where all the low-level details (such as texture formats) are handled by the
 -- C++ side and you generally just build chains.
 
-local transition_start = -2.0
-local transition_end = -1.0
-local zoom_src = 0.0
-local zoom_dst = 1.0
-local zoom_poi = 0   -- which input to zoom in on
-local fade_src_signal = 0
-local fade_dst_signal = 0
-
-local input0_neutral_color = {0.5, 0.5, 0.5}
-local input1_neutral_color = {0.5, 0.5, 0.5}
-
-local live_signal_num = 0
-local preview_signal_num = 1
+local state = {
+	transition_start = -2.0,
+	transition_end = -1.0,
+	transition_type = 0,
+	transition_src_signal = 0,
+	transition_dst_signal = 0,
+
+	neutral_colors = {
+		{0.5, 0.5, 0.5},  -- Input 0.
+		{0.5, 0.5, 0.5}   -- Input 1.
+	},
+
+	live_signal_num = 0,
+	preview_signal_num = 1
+}
 
 -- Valid values for live_signal_num and preview_signal_num.
 local INPUT0_SIGNAL_NUM = 0
@@ -27,11 +29,12 @@ local INPUT1_SIGNAL_NUM = 1
 local SBS_SIGNAL_NUM = 2
 local STATIC_SIGNAL_NUM = 3
 
--- “fake” signal number that signifies that we are fading from one input
--- to the next.
-local FADE_SIGNAL_NUM = 4
+-- Valid values for transition_type. (Cuts are done directly, so they need no entry.)
+local NO_TRANSITION = 0
+local ZOOM_TRANSITION = 1  -- Also for slides.
+local FADE_TRANSITION = 2
 
--- Last width/height/resolution for each channel, if we have it.
+-- Last width/height/frame rate for each channel, if we have it.
 -- Note that unlike the values we get from Nageru, the resolution is per
 -- frame and not per field, since we deinterlace.
 local last_resolution = {}
@@ -57,7 +60,6 @@ end
 function make_sbs_input(chain, signal, deint, hq)
 	local input = chain:add_live_input(not deint, deint)  -- Override bounce only if not deinterlacing.
 	input:connect_signal(signal)
-	local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
 
 	local resample_effect = nil
 	local resize_effect = nil
@@ -66,6 +68,7 @@ function make_sbs_input(chain, signal, deint, hq)
 	else
 		resize_effect = chain:add_effect(ResizeEffect.new())
 	end
+	local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
 
 	local padding_effect = chain:add_effect(IntegralPaddingEffect.new())
 
@@ -79,11 +82,11 @@ function make_sbs_input(chain, signal, deint, hq)
 end
 
 -- The main live chain.
-function make_sbs_chain(input0_deint, input1_deint, hq)
+function make_sbs_chain(input0_type, input1_type, hq)
 	local chain = EffectChain.new(16, 9)
 
-	local input0 = make_sbs_input(chain, INPUT0_SIGNAL_NUM, input0_deint, hq)
-	local input1 = make_sbs_input(chain, INPUT1_SIGNAL_NUM, input1_deint, hq)
+	local input0 = make_sbs_input(chain, INPUT0_SIGNAL_NUM, input0_type == "livedeint", hq)
+	local input1 = make_sbs_input(chain, INPUT1_SIGNAL_NUM, input1_type == "livedeint", hq)
 
 	input0.padding_effect:set_vec4("border_color", 0.0, 0.0, 0.0, 1.0)
 	input1.padding_effect:set_vec4("border_color", 0.0, 0.0, 0.0, 0.0)
@@ -104,18 +107,15 @@ local sbs_chains = make_cartesian_product({
 	{"live", "livedeint"},  -- input1_type
 	{true, false}           -- hq
 }, function(input0_type, input1_type, hq)
-	local input0_deint = (input0_type == "livedeint")
-	local input1_deint = (input1_type == "livedeint")
-	return make_sbs_chain(input0_deint, input1_deint, hq)
+	return make_sbs_chain(input0_type, input1_type, hq)
 end)
 
 function make_fade_input(chain, signal, live, deint, scale)
 	local input, wb_effect, resample_effect, last
 	if live then
 		input = chain:add_live_input(false, deint)
-		wb_effect = chain:add_effect(WhiteBalanceEffect.new())
 		input:connect_signal(signal)
-		last = wb_effect
+		last = input
 	else
 		input = chain:add_effect(ImageInput.new("bg.jpeg"))
 		last = input
@@ -128,6 +128,12 @@ function make_fade_input(chain, signal, live, deint, scale)
 		last = resample_effect
 	end
 
+	-- Make sure to put the white balance after the scaling (usually more efficient).
+	if live then
+		wb_effect = chain:add_effect(WhiteBalanceEffect.new())
+		last = wb_effect
+	end
+
 	return {
 		input = input,
 		wb_effect = wb_effect,
@@ -177,11 +183,9 @@ function make_simple_chain(input_deint, input_scale, hq)
 
 	local input = chain:add_live_input(false, input_deint)
 	input:connect_signal(0)  -- First input card. Can be changed whenever you want.
-	local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
-	chain:finalize(hq)
 
 	local resample_effect, resize_effect
-	if scale then
+	if input_scale then
 		if hq then
 			resample_effect = chain:add_effect(ResampleEffect.new())
 		else
@@ -189,6 +193,9 @@ function make_simple_chain(input_deint, input_scale, hq)
 		end
 	end
 
+	local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
+	chain:finalize(hq)
+
 	return {
 		chain = chain,
 		input = input,
@@ -234,7 +241,7 @@ function needs_scale(signals, signal_num, width, height)
 		-- We assume this is already correctly scaled at load time.
 		return false
 	end
-	assert(signal_num == INPUT0_SIGNAL_NUM or signal_num == INPUT1_SIGNAL_NUM)
+	assert(is_plain_signal(signal_num))
 	return (signals:get_width(signal_num) ~= width or signals:get_height(signal_num) ~= height)
 end
 
@@ -255,10 +262,36 @@ function num_channels()
 	return 4
 end
 
+function is_plain_signal(num)
+	return num == INPUT0_SIGNAL_NUM or num == INPUT1_SIGNAL_NUM
+end
+
+-- Helper function to write e.g. “720p60”. The difference between this
+-- and get_channel_resolution_raw() is that this one also can say that
+-- there's no signal.
+function get_channel_resolution(signal_num)
+	local res = last_resolution[signal_num]
+	if (not res) or not res.is_connected then
+		return "disconnected"
+	end
+	if res.height <= 0 then
+		return "no signal"
+	end
+	if not res.has_signal then
+		if res.height == 525 then
+			-- Special mode for the USB3 cards.
+			return "no signal"
+		end
+		return get_channel_resolution_raw(res) .. ", no signal"
+	else
+		return get_channel_resolution_raw(res)
+	end
+end
+
 -- Helper function to write e.g. “60” or “59.94”.
-function get_frame_rate(signal_num)
-	local nom = last_resolution[signal_num].frame_rate_nom
-	local den = last_resolution[signal_num].frame_rate_den
+function get_frame_rate(res)
+	local nom = res.frame_rate_nom
+	local den = res.frame_rate_den
 	if nom % den == 0 then
 		return nom / den
 	else
@@ -267,18 +300,11 @@ function get_frame_rate(signal_num)
 end
 
 -- Helper function to write e.g. “720p60”.
-function get_channel_resolution(signal_num)
-	if last_resolution[signal_num] then
-		if last_resolution[signal_num].height == 0 or
-		   last_resolution[signal_num].height == 525 then
-			return "no signal"
-		elseif last_resolution[signal_num].interlaced then
-			return last_resolution[signal_num].height .. "i" .. get_frame_rate(signal_num)
-		else
-			return last_resolution[signal_num].height .. "p" .. get_frame_rate(signal_num)
-		end
+function get_channel_resolution_raw(res)
+	if res.interlaced then
+		return res.height .. "i" .. get_frame_rate(res)
 	else
-		return "no signal"
+		return res.height .. "p" .. get_frame_rate(res)
 	end
 end
 
@@ -287,20 +313,23 @@ end
 -- Called at the start of the program, and then each frame for live
 -- channels in case they change resolution.
 function channel_name(channel)
-	if channel == 2 then
-		return "Input 1 (" .. get_channel_resolution(0) .. ")"
-	elseif channel == 3 then
-		return "Input 2 (" .. get_channel_resolution(1) .. ")"
-	elseif channel == 4 then
+	local signal_num = channel - 2
+	if is_plain_signal(signal_num) then
+		return "Input " .. (signal_num + 1) .. " (" .. get_channel_resolution(signal_num) .. ")"
+	elseif signal_num == SBS_SIGNAL_NUM then
 		return "Side-by-side"
-	elseif channel == 5 then
+	elseif signal_num == STATIC_SIGNAL_NUM then
 		return "Static picture"
 	end
 end
 
 -- API ENTRY POINT
 -- Returns, given a channel number, which signal it corresponds to (starting from 0).
--- Should return -1 if the channel does not correspond to a simple signal.
+-- Should return -1 if the channel does not correspond to a simple signal
+-- (one connected to a capture card, or a video input). The information is used for
+-- whether right-click on the channel should bring up a context menu or not,
+-- typically containing an input selector, resolution menu etc.
+--
 -- Called once for each channel, at the start of the program.
 -- Will never be called for live (0) or preview (1).
 function channel_signal(channel)
@@ -313,147 +342,155 @@ function channel_signal(channel)
 	end
 end
 
+-- API ENTRY POINT
+-- Called every frame. Returns the color (if any) to paint around the given
+-- channel. Returns a CSS color (typically to mark live and preview signals);
+-- "transparent" is allowed.
+-- Will never be called for live (0) or preview (1).
+function channel_color(channel)
+	if state.transition_type ~= NO_TRANSITION then
+		if channel_involved_in(channel, state.transition_src_signal) or
+		   channel_involved_in(channel, state.transition_dst_signal) then
+			return "#f00"
+		end
+	else
+		if channel_involved_in(channel, state.live_signal_num) then
+			return "#f00"
+		end
+	end
+	if channel_involved_in(channel, state.preview_signal_num) then
+		return "#0f0"
+	end
+	return "transparent"
+end
+
+function channel_involved_in(channel, signal_num)
+	if is_plain_signal(signal_num) then
+		return channel == (signal_num + 2)
+	end
+	if signal_num == SBS_SIGNAL_NUM then
+		return (channel == 2 or channel == 3)
+	end
+	if signal_num == STATIC_SIGNAL_NUM then
+		return (channel == 5)
+	end
+	return false
+end
+
 -- API ENTRY POINT
 -- Returns if a given channel supports setting white balance (starting from 2).
 -- Called only once for each channel, at the start of the program.
 function supports_set_wb(channel)
-	return channel == 2 or channel == 3
+	return is_plain_signal(channel - 2)
 end
 
 -- API ENTRY POINT
 -- Gets called with a new gray point when the white balance is changing.
 -- The color is in linear light (not sRGB gamma).
 function set_wb(channel, red, green, blue)
-	if channel == 2 then
-		input0_neutral_color = { red, green, blue }
-	elseif channel == 3 then
-		input1_neutral_color = { red, green, blue }
+	if is_plain_signal(channel - 2) then
+		state.neutral_colors[channel - 2 + 1] = { red, green, blue }
 	end
 end
 
 function finish_transitions(t)
-	-- If live is SBS but de-facto single, make it so.
-	if live_signal_num == SBS_SIGNAL_NUM and t >= transition_end and zoom_dst == 1.0 then
-		live_signal_num = zoom_poi
+	if state.transition_type ~= NO_TRANSITION and t >= state.transition_end then
+		state.live_signal_num = state.transition_dst_signal
+		state.transition_type = NO_TRANSITION
 	end
+end
 
-	-- If live is fade but de-facto single, make it so.
-	if live_signal_num == FADE_SIGNAL_NUM and t >= transition_end then
-		live_signal_num = fade_dst_signal
-	end
+function in_transition(t)
+       return t >= state.transition_start and t <= state.transition_end
 end
 
 -- API ENTRY POINT
 -- Called every frame.
 function get_transitions(t)
+	if in_transition(t) then
+		-- Transition already in progress, the only thing we can do is really
+		-- cut to the preview. (TODO: Make an “abort” and/or “finish”, too?)
+		return {"Cut"}
+	end
+
 	finish_transitions(t)
 
-	if live_signal_num == preview_signal_num then
+	if state.live_signal_num == state.preview_signal_num then
+		-- No transitions possible.
 		return {}
 	end
 
-	if live_signal_num == SBS_SIGNAL_NUM and t >= transition_start and t <= transition_end then
-		-- Zoom in progress.
-		return {"Cut"}
-	end
-
-	if (live_signal_num == INPUT0_SIGNAL_NUM or
-	    live_signal_num == INPUT1_SIGNAL_NUM or
-	    live_signal_num == STATIC_SIGNAL_NUM) and
-	   (preview_signal_num == INPUT0_SIGNAL_NUM or
-	    preview_signal_num == INPUT1_SIGNAL_NUM or
-	    preview_signal_num == STATIC_SIGNAL_NUM) then
+	if (is_plain_signal(state.live_signal_num) or state.live_signal_num == STATIC_SIGNAL_NUM) and
+	   (is_plain_signal(state.preview_signal_num) or state.preview_signal_num == STATIC_SIGNAL_NUM) then
 		return {"Cut", "", "Fade"}
 	end
 
 	-- Various zooms.
-	if live_signal_num == SBS_SIGNAL_NUM and
-	   (preview_signal_num == INPUT0_SIGNAL_NUM or preview_signal_num == INPUT1_SIGNAL_NUM) then
+	if state.live_signal_num == SBS_SIGNAL_NUM and is_plain_signal(state.preview_signal_num) then
 		return {"Cut", "Zoom in"}
-	elseif (live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM) and
-	       preview_signal_num == SBS_SIGNAL_NUM then
+	elseif is_plain_signal(state.live_signal_num) and state.preview_signal_num == SBS_SIGNAL_NUM then
 		return {"Cut", "Zoom out"}
 	end
 
 	return {"Cut"}
 end
 
+function swap_preview_live()
+	local temp = state.live_signal_num
+	state.live_signal_num = state.preview_signal_num
+	state.preview_signal_num = temp
+end
+
+function start_transition(type_, t, duration)
+	state.transition_start = t
+	state.transition_end = t + duration
+	state.transition_type = type_
+	state.transition_src_signal = state.live_signal_num
+	state.transition_dst_signal = state.preview_signal_num
+	swap_preview_live()
+end
+
+-- API ENTRY POINT
+-- Called when the user clicks a transition button.
 function transition_clicked(num, t)
 	if num == 0 then
 		-- Cut.
-		if live_signal_num == FADE_SIGNAL_NUM then
-			-- Ongoing fade; finish it immediately.
-			finish_transitions(transition_end)
+		if in_transition(t) then
+			-- Ongoing transition; finish it immediately before the cut.
+			finish_transitions(state.transition_end)
 		end
 
-		local temp = live_signal_num
-		live_signal_num = preview_signal_num
-		preview_signal_num = temp
-
-		if live_signal_num == SBS_SIGNAL_NUM then
-			-- Just cut to SBS, we need to reset any zooms.
-			zoom_src = 1.0
-			zoom_dst = 0.0
-			transition_start = -2.0
-			transition_end = -1.0
-		end
+		swap_preview_live()
 	elseif num == 1 then
 		-- Zoom.
-
 		finish_transitions(t)
 
-		if live_signal_num == preview_signal_num then
+		if state.live_signal_num == state.preview_signal_num then
 			-- Nothing to do.
 			return
 		end
 
-		if (live_signal_num == INPUT0_SIGNAL_NUM and preview_signal_num == INPUT1_SIGNAL_NUM) or
-		   (live_signal_num == INPUT1_SIGNAL_NUM and preview_signal_num == INPUT0_SIGNAL_NUM) then
+		if is_plain_signal(state.live_signal_num) and is_plain_signal(state.preview_signal_num) then
 			-- We can't zoom between these. Just make a cut.
-			io.write("Cutting from " .. live_signal_num .. " to " .. live_signal_num .. "\n")
-			local temp = live_signal_num
-			live_signal_num = preview_signal_num
-			preview_signal_num = temp
+			io.write("Cutting from " .. state.live_signal_num .. " to " .. state.live_signal_num .. "\n")
+			swap_preview_live()
 			return
 		end
 
-		if live_signal_num == SBS_SIGNAL_NUM and
-		   (preview_signal_num == INPUT0_SIGNAL_NUM or preview_signal_num == INPUT1_SIGNAL_NUM) then
-			-- Zoom in from SBS to single.
-			transition_start = t
-			transition_end = t + 1.0
-			zoom_src = 0.0
-			zoom_dst = 1.0
-			zoom_poi = preview_signal_num
-			preview_signal_num = SBS_SIGNAL_NUM
-		elseif (live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM) and
-		       preview_signal_num == SBS_SIGNAL_NUM then
-			-- Zoom out from single to SBS.
-			transition_start = t
-			transition_end = t + 1.0
-			zoom_src = 1.0
-			zoom_dst = 0.0
-			preview_signal_num = live_signal_num
-			zoom_poi = live_signal_num
-			live_signal_num = SBS_SIGNAL_NUM
+		if (state.live_signal_num == SBS_SIGNAL_NUM and is_plain_signal(state.preview_signal_num)) or
+		   (state.preview_signal_num == SBS_SIGNAL_NUM and is_plain_signal(state.live_signal_num)) then
+			start_transition(ZOOM_TRANSITION, t, 1.0)
 		end
 	elseif num == 2 then
 		finish_transitions(t)
 
 		-- Fade.
-		if (live_signal_num ~= preview_signal_num) and
-		   (live_signal_num == INPUT0_SIGNAL_NUM or
-		    live_signal_num == INPUT1_SIGNAL_NUM or
-		    live_signal_num == STATIC_SIGNAL_NUM) and
-		   (preview_signal_num == INPUT0_SIGNAL_NUM or
-		    preview_signal_num == INPUT1_SIGNAL_NUM or
-		    preview_signal_num == STATIC_SIGNAL_NUM) then
-			transition_start = t
-			transition_end = t + 1.0
-			fade_src_signal = live_signal_num
-			fade_dst_signal = preview_signal_num
-			preview_signal_num = live_signal_num
-			live_signal_num = FADE_SIGNAL_NUM
+		if (state.live_signal_num ~= state.preview_signal_num) and
+		   (is_plain_signal(state.live_signal_num) or
+		    state.live_signal_num == STATIC_SIGNAL_NUM) and
+		   (is_plain_signal(state.preview_signal_num) or
+		    state.preview_signal_num == STATIC_SIGNAL_NUM) then
+			start_transition(FADE_TRANSITION, t, 1.0)
 		else
 			-- Fades involving SBS are ignored (we have no chain for it).
 		end
@@ -462,7 +499,39 @@ end
 
 -- API ENTRY POINT
 function channel_clicked(num)
-	preview_signal_num = num
+	state.preview_signal_num = num
+end
+
+function get_fade_chain(state, signals, t, width, height, input_resolution)
+	local input0_type = get_input_type(signals, state.transition_src_signal)
+	local input0_scale = needs_scale(signals, state.transition_src_signal, width, height)
+	local input1_type = get_input_type(signals, state.transition_dst_signal)
+	local input1_scale = needs_scale(signals, state.transition_dst_signal, width, height)
+	local chain = fade_chains[input0_type][input0_scale][input1_type][input1_scale][true]
+	local prepare = function()
+		if input0_type == "live" or input0_type == "livedeint" then
+			chain.input0.input:connect_signal(state.transition_src_signal)
+			set_neutral_color_from_signal(state, chain.input0.wb_effect, state.transition_src_signal)
+		end
+		set_scale_parameters_if_needed(chain.input0, width, height)
+		if input1_type == "live" or input1_type == "livedeint" then
+			chain.input1.input:connect_signal(state.transition_dst_signal)
+			set_neutral_color_from_signal(state, chain.input1.wb_effect, state.transition_dst_signal)
+		end
+		set_scale_parameters_if_needed(chain.input1, width, height)
+		local tt = calc_fade_progress(t, state.transition_start, state.transition_end)
+
+		chain.mix_effect:set_float("strength_first", 1.0 - tt)
+		chain.mix_effect:set_float("strength_second", tt)
+	end
+	return chain.chain, prepare
+end
+
+-- SBS code (live_signal_num == SBS_SIGNAL_NUM, or in a transition to/from it).
+function get_sbs_chain(signals, t, width, height, input_resolution)
+	local input0_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
+	local input1_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
+	return sbs_chains[input0_type][input1_type][true]
 end
 
 -- API ENTRY POINT
@@ -496,6 +565,8 @@ function get_chain(num, t, width, height, signals)
 			width = signals:get_width(signal_num),
 			height = signals:get_height(signal_num),
 			interlaced = signals:get_interlaced(signal_num),
+			is_connected = signals:get_is_connected(signal_num),
+			has_signal = signals:get_has_signal(signal_num),
 			frame_rate_nom = signals:get_frame_rate_nom(signal_num),
 			frame_rate_den = signals:get_frame_rate_den(signal_num)
 		}
@@ -515,99 +586,64 @@ function get_chain(num, t, width, height, signals)
 	end
 	last_resolution = input_resolution
 
+	-- Make a (semi-shallow) copy of the current state, so that the returned prepare function
+	-- is unaffected by state changes made by the UI before it is rendered.
+	local state_copy = {}
+	for key, value in pairs(state) do
+		state_copy[key] = value
+	end
+	state_copy.neutral_colors = { unpack(state.neutral_colors) }
+
 	if num == 0 then  -- Live.
-		if live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM then  -- Plain input.
-			local input_type = get_input_type(signals, live_signal_num)
-			local input_scale = needs_scale(signals, live_signal_num, width, height)
-			local chain = simple_chains[input_type][input_scale][true]
-			prepare = function()
-				chain.input:connect_signal(live_signal_num)
-				set_scale_parameters_if_needed(chain, width, height)
-				set_neutral_color_from_signal(chain.wb_effect, live_signal_num)
+		finish_transitions(t)
+		if state.transition_type == ZOOM_TRANSITION then
+			-- Transition in or out of SBS.
+			local chain = get_sbs_chain(signals, t, width, height, input_resolution)
+			local prepare = function()
+				prepare_sbs_chain(state_copy, chain, calc_zoom_progress(state_copy, t), state_copy.transition_type, state_copy.transition_src_signal, state_copy.transition_dst_signal, width, height, input_resolution)
 			end
 			return chain.chain, prepare
-		elseif live_signal_num == STATIC_SIGNAL_NUM then  -- Static picture.
-			prepare = function()
-			end
-			return static_chain_hq, prepare
-		elseif live_signal_num == FADE_SIGNAL_NUM then  -- Fade.
-			local input0_type = get_input_type(signals, fade_src_signal)
-			local input0_scale = needs_scale(signals, fade_src_signal, width, height)
-			local input1_type = get_input_type(signals, fade_dst_signal)
-			local input1_scale = needs_scale(signals, fade_dst_signal, width, height)
-			local chain = fade_chains[input0_type][input0_scale][input1_type][input1_scale][true]
-			prepare = function()
-				if input0_type == "live" then
-					chain.input0.input:connect_signal(fade_src_signal)
-					set_neutral_color_from_signal(chain.input0.wb_effect, fade_src_signal)
-				end
-				set_scale_parameters_if_needed(chain.input0, width, height)
-				if input1_type == "live" then
-					chain.input1.input:connect_signal(fade_dst_signal)
-					set_neutral_color_from_signal(chain.input1.wb_effect, fade_dst_signal)
-				end
-				set_scale_parameters_if_needed(chain.input1, width, height)
-				local tt = calc_fade_progress(t, transition_start, transition_end)
-
-				chain.mix_effect:set_float("strength_first", 1.0 - tt)
-				chain.mix_effect:set_float("strength_second", tt)
+		elseif state.transition_type == NO_TRANSITION and state.live_signal_num == SBS_SIGNAL_NUM then
+			-- Static SBS view.
+			local chain = get_sbs_chain(signals, t, width, height, input_resolution)
+			local prepare = function()
+				prepare_sbs_chain(state_copy, chain, 0.0, NO_TRANSITION, 0, SBS_SIGNAL_NUM, width, height, input_resolution)
 			end
 			return chain.chain, prepare
-		end
-
-		-- SBS code (live_signal_num == SBS_SIGNAL_NUM).
-		local input0_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
-		local input1_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
-		if t > transition_end and zoom_dst == 1.0 then
-			-- Special case: Show only the single image on screen.
-			local input0_scale = needs_scale(signals, fade_src_signal, width, height)
-			local chain = simple_chains[input0_type][input0_scale][true]
-			prepare = function()
-				chain.input:connect_signal(INPUT0_SIGNAL_NUM)
+		elseif state.transition_type == FADE_TRANSITION then
+			return get_fade_chain(state_copy, signals, t, width, height, input_resolution)
+		elseif is_plain_signal(state.live_signal_num) then
+			local input_type = get_input_type(signals, state.live_signal_num)
+			local input_scale = needs_scale(signals, state.live_signal_num, width, height)
+			local chain = simple_chains[input_type][input_scale][true]
+			local prepare = function()
+				chain.input:connect_signal(state_copy.live_signal_num)
 				set_scale_parameters_if_needed(chain, width, height)
-				set_neutral_color(chain.wb_effect, input0_neutral_color)
+				set_neutral_color_from_signal(state_copy, chain.wb_effect, state_copy.live_signal_num)
 			end
 			return chain.chain, prepare
-		end
-		local chain = sbs_chains[input0_type][input1_type][true]
-		prepare = function()
-			if t < transition_start then
-				prepare_sbs_chain(chain, zoom_src, width, height, input_resolution)
-			elseif t > transition_end then
-				prepare_sbs_chain(chain, zoom_dst, width, height, input_resolution)
-			else
-				local tt = (t - transition_start) / (transition_end - transition_start)
-				-- Smooth it a bit.
-				tt = math.sin(tt * 3.14159265358 * 0.5)
-				prepare_sbs_chain(chain, zoom_src + (zoom_dst - zoom_src) * tt, width, height, input_resolution)
+		elseif state.live_signal_num == STATIC_SIGNAL_NUM then  -- Static picture.
+			local prepare = function()
 			end
+			return static_chain_hq, prepare
+		else
+			assert(false)
 		end
-		return chain.chain, prepare
 	end
 	if num == 1 then  -- Preview.
-		num = preview_signal_num + 2
+		num = state.preview_signal_num + 2
 	end
 
 	-- Individual preview inputs.
-	if num == INPUT0_SIGNAL_NUM + 2 then
-		local input_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
-		local input_scale = needs_scale(signals, INPUT0_SIGNAL_NUM, width, height)
-		local chain = simple_chains[input_type][input_scale][false]
-		prepare = function()
-			chain.input:connect_signal(INPUT0_SIGNAL_NUM)
-			set_scale_parameters_if_needed(chain, width, height)
-			set_neutral_color(chain.wb_effect, input0_neutral_color)
-		end
-		return chain.chain, prepare
-	end
-	if num == INPUT1_SIGNAL_NUM + 2 then
-		local input_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
-		local input_scale = needs_scale(signals, INPUT1_SIGNAL_NUM, width, height)
+	if is_plain_signal(num - 2) then
+		local signal_num = num - 2
+		local input_type = get_input_type(signals, signal_num)
+		local input_scale = needs_scale(signals, signal_num, width, height)
 		local chain = simple_chains[input_type][input_scale][false]
-		prepare = function()
-			chain.input:connect_signal(INPUT1_SIGNAL_NUM)
+		local prepare = function()
+			chain.input:connect_signal(signal_num)
 			set_scale_parameters_if_needed(chain, width, height)
-			set_neutral_color(chain.wb_effect, input1_neutral_color)
+			set_neutral_color(chain.wb_effect, state_copy.neutral_colors[signal_num + 1])
 		end
 		return chain.chain, prepare
 	end
@@ -615,13 +651,13 @@ function get_chain(num, t, width, height, signals)
 		local input0_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
 		local input1_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
 		local chain = sbs_chains[input0_type][input1_type][false]
-		prepare = function()
-			prepare_sbs_chain(chain, 0.0, width, height, input_resolution)
+		local prepare = function()
+			prepare_sbs_chain(state_copy, chain, 0.0, NO_TRANSITION, 0, SBS_SIGNAL_NUM, width, height, input_resolution)
 		end
 		return chain.chain, prepare
 	end
 	if num == STATIC_SIGNAL_NUM + 2 then
-		prepare = function()
+		local prepare = function()
 		end
 		return static_chain_lq, prepare
 	end
@@ -633,12 +669,20 @@ function place_rectangle(resample_effect, resize_effect, padding_effect, x0, y0,
 	local srcy0 = 0.0
 	local srcy1 = 1.0
 
+	padding_effect:set_int("width", screen_width)
+	padding_effect:set_int("height", screen_height)
+
 	-- Cull.
 	if x0 > screen_width or x1 < 0.0 or y0 > screen_height or y1 < 0.0 then
-		resample_effect:set_int("width", 1)
-		resample_effect:set_int("height", 1)
-		resample_effect:set_float("zoom_x", screen_width)
-		resample_effect:set_float("zoom_y", screen_height)
+		if resample_effect ~= nil then
+			resample_effect:set_int("width", 1)
+			resample_effect:set_int("height", 1)
+			resample_effect:set_float("zoom_x", screen_width)
+			resample_effect:set_float("zoom_y", screen_height)
+		else
+			resize_effect:set_int("width", 1)
+			resize_effect:set_int("height", 1)
+		end
 		padding_effect:set_int("left", screen_width + 100)
 		padding_effect:set_int("top", screen_height + 100)
 		return
@@ -718,83 +762,116 @@ function lerp(a, b, t)
 	return a + (b - a) * t
 end
 
-function prepare_sbs_chain(chain, t, screen_width, screen_height, input_resolution)
+function lerp_pos(a, b, t)
+	return {
+		x0 = lerp(a.x0, b.x0, t),
+		y0 = lerp(a.y0, b.y0, t),
+		x1 = lerp(a.x1, b.x1, t),
+		y1 = lerp(a.y1, b.y1, t)
+	}
+end
+
+function pos_from_top_left(x, y, width, height, screen_width, screen_height)
+	local xs = screen_width / 1280.0
+	local ys = screen_height / 720.0
+	return {
+		x0 = round(xs * x),
+		y0 = round(ys * y),
+		x1 = round(xs * (x + width)),
+		y1 = round(ys * (y + height))
+	}
+end
+
+function prepare_sbs_chain(state, chain, t, transition_type, src_signal, dst_signal, screen_width, screen_height, input_resolution)
 	chain.input0.input:connect_signal(0)
 	chain.input1.input:connect_signal(1)
-	set_neutral_color(chain.input0.wb_effect, input0_neutral_color)
-	set_neutral_color(chain.input1.wb_effect, input1_neutral_color)
+	set_neutral_color(chain.input0.wb_effect, state.neutral_colors[1])
+	set_neutral_color(chain.input1.wb_effect, state.neutral_colors[2])
 
 	-- First input is positioned (16,48) from top-left.
-	local width0 = round(848 * screen_width/1280.0)
-	local height0 = round(width0 * 9.0 / 16.0)
-
-	local top0 = 48 * screen_height/720.0
-	local left0 = 16 * screen_width/1280.0
-	local bottom0 = top0 + height0
-	local right0 = left0 + width0
-
 	-- Second input is positioned (16,48) from the bottom-right.
-	local width1 = round(384 * screen_width/1280.0)
-	local height1 = round(216 * screen_height/720.0)
-
-	local bottom1 = screen_height - 48 * screen_height/720.0
-	local right1 = screen_width - 16 * screen_width/1280.0
-	local top1 = bottom1 - height1
-	local left1 = right1 - width1
-
-	-- Interpolate between the fullscreen and side-by-side views.
-	local scale0, tx0, tx0
-	if zoom_poi == INPUT0_SIGNAL_NUM then
-		local new_left0 = lerp(left0, 0, t)
-		local new_right0 = lerp(right0, screen_width, t)
-		local new_top0 = lerp(top0, 0, t)
-		local new_bottom0 = lerp(bottom0, screen_height, t)
-
-		scale0 = (new_right0 - new_left0) / width0  -- Same vertically and horizonally.
-		tx0 = new_left0 - left0 * scale0
-		ty0 = new_top0 - top0 * scale0
+	local pos0 = pos_from_top_left(16, 48, 848, 477, screen_width, screen_height)
+	local pos1 = pos_from_top_left(1280 - 384 - 16, 720 - 216 - 48, 384, 216, screen_width, screen_height)
+
+	local pos_fs = { x0 = 0, y0 = 0, x1 = screen_width, y1 = screen_height }
+	local affine_param
+	if transition_type == NO_TRANSITION then
+		-- Static SBS view.
+		affine_param = { sx = 1.0, sy = 1.0, tx = 0.0, ty = 0.0 }   -- Identity.
 	else
-		local new_left1 = lerp(left1, 0, t)
-		local new_right1 = lerp(right1, screen_width, t)
-		local new_top1 = lerp(top1, 0, t)
-		local new_bottom1 = lerp(bottom1, screen_height, t)
+		-- Zooming to/from SBS view into or out of a single view.
+		assert(transition_type == ZOOM_TRANSITION)
+		local signal, real_t
+		if src_signal == SBS_SIGNAL_NUM then
+			signal = dst_signal
+			real_t = t
+		else
+			assert(dst_signal == SBS_SIGNAL_NUM)
+			signal = src_signal
+			real_t = 1.0 - t
+		end
 
-		scale0 = (new_right1 - new_left1) / width1  -- Same vertically and horizonally.
-		tx0 = new_left1 - left1 * scale0
-		ty0 = new_top1 - top1 * scale0
+		if signal == INPUT0_SIGNAL_NUM then
+			affine_param = find_affine_param(pos0, lerp_pos(pos0, pos_fs, real_t))
+		elseif signal == INPUT1_SIGNAL_NUM then
+			affine_param = find_affine_param(pos1, lerp_pos(pos1, pos_fs, real_t))
+		end
 	end
 
-	top0 = top0 * scale0 + ty0
-	bottom0 = bottom0 * scale0 + ty0
-	left0 = left0 * scale0 + tx0
-	right0 = right0 * scale0 + tx0
+	-- NOTE: input_resolution is not 1-indexed, unlike usual Lua arrays.
+	place_rectangle_with_affine(chain.input0.resample_effect, chain.input0.resize_effect, chain.input0.padding_effect, pos0, affine_param, screen_width, screen_height, input_resolution[0].width, input_resolution[0].height)
+	place_rectangle_with_affine(chain.input1.resample_effect, chain.input1.resize_effect, chain.input1.padding_effect, pos1, affine_param, screen_width, screen_height, input_resolution[1].width, input_resolution[1].height)
+end
 
-	top1 = top1 * scale0 + ty0
-	bottom1 = bottom1 * scale0 + ty0
-	left1 = left1 * scale0 + tx0
-	right1 = right1 * scale0 + tx0
-	place_rectangle(chain.input0.resample_effect, chain.input0.resize_effect, chain.input0.padding_effect, left0, top0, right0, bottom0, screen_width, screen_height, input_resolution[0].width, input_resolution[0].height)
-	place_rectangle(chain.input1.resample_effect, chain.input1.resize_effect, chain.input1.padding_effect, left1, top1, right1, bottom1, screen_width, screen_height, input_resolution[1].width, input_resolution[1].height)
+-- Find the transformation that changes the first rectangle to the second one.
+function find_affine_param(a, b)
+	local sx = (b.x1 - b.x0) / (a.x1 - a.x0)
+	local sy = (b.y1 - b.y0) / (a.y1 - a.y0)
+	return {
+		sx = sx,
+		sy = sy,
+		tx = b.x0 - a.x0 * sx,
+		ty = b.y0 - a.y0 * sy
+	}
+end
+
+function place_rectangle_with_affine(resample_effect, resize_effect, padding_effect, pos, aff, screen_width, screen_height, input_width, input_height)
+	local x0 = pos.x0 * aff.sx + aff.tx
+	local x1 = pos.x1 * aff.sx + aff.tx
+	local y0 = pos.y0 * aff.sy + aff.ty
+	local y1 = pos.y1 * aff.sy + aff.ty
+
+	place_rectangle(resample_effect, resize_effect, padding_effect, x0, y0, x1, y1, screen_width, screen_height, input_width, input_height)
 end
 
 function set_neutral_color(effect, color)
 	effect:set_vec3("neutral_color", color[1], color[2], color[3])
 end
 
-function set_neutral_color_from_signal(effect, signal)
-	if signal == INPUT0_SIGNAL_NUM then
-		set_neutral_color(effect, input0_neutral_color)
+function set_neutral_color_from_signal(state, effect, signal)
+	if is_plain_signal(signal) then
+		set_neutral_color(effect, state.neutral_colors[signal - INPUT0_SIGNAL_NUM + 1])
+	end
+end
+
+function calc_zoom_progress(state, t)
+	if t < state.transition_start then
+		return 0.0
+	elseif t > state.transition_end then
+		return 1.0
 	else
-		set_neutral_color(effect, input1_neutral_color)
+		local tt = (t - state.transition_start) / (state.transition_end - state.transition_start)
+		-- Smooth it a bit.
+		return math.sin(tt * 3.14159265358 * 0.5)
 	end
 end
 
 function calc_fade_progress(t, transition_start, transition_end)
 	local tt = (t - transition_start) / (transition_end - transition_start)
 	if tt < 0.0 then
-		tt = 0.0
+		return 0.0
 	elseif tt > 1.0 then
-		tt = 1.0
+		return 1.0
 	end
 
 	-- Make the fade look maybe a tad more natural, by pumping it