X-Git-Url: https://git.sesse.net/?p=nageru;a=blobdiff_plain;f=theme.lua;h=77a1ff15cde855daf459367af3be3adc764d77d4;hp=82339f8d33db7c03d9fb8c51f1b6060373cef6b9;hb=d3e48df512d9476d3849227067792a3537bb094e;hpb=6d011e4760be6e45680b41a98b9049c1ec44c951

diff --git a/theme.lua b/theme.lua
index 82339f8..77a1ff1 100644
--- a/theme.lua
+++ b/theme.lua
@@ -6,86 +6,866 @@
 -- Themes are written in Lua, which reflects a simplified form of the Movit API
 -- where all the low-level details (such as texture formats) are handled by the
 -- C++ side and you generally just build chains.
-io.write("hello from lua\n");
 
-local live_signal_num = 0;
-local preview_signal_num = 1;
+local transition_start = -2.0
+local transition_end = -1.0
+local transition_type = 0
+local transition_src_signal = 0
+local transition_dst_signal = 0
 
--- The main live chain. Currently just about input 0 with some color correction.
-local main_chain = EffectChain.new(16, 9);
-local input0 = main_chain:add_live_input();
-input0:connect_signal(0);
-local wb_effect = main_chain:add_effect(WhiteBalanceEffect.new(), input0);
-main_chain:finalize(true);
--- local input1 = main_chain.add_input(Inputs.create(1));
--- local resample_effect = main_chain.add_effect(ResampleEffect.new(), input0);
--- local padding_effect = main_chain.add_effect(IntegralPaddingEffect.new());
+local neutral_colors = {
+	{0.5, 0.5, 0.5},  -- Input 0.
+	{0.5, 0.5, 0.5}   -- Input 1.
+}
+
+local live_signal_num = 0
+local preview_signal_num = 1
+
+-- Valid values for live_signal_num and preview_signal_num.
+local INPUT0_SIGNAL_NUM = 0
+local INPUT1_SIGNAL_NUM = 1
+local SBS_SIGNAL_NUM = 2
+local STATIC_SIGNAL_NUM = 3
+
+-- 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/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 = {}
+
+-- Utility function to help creating many similar chains that can differ
+-- in a free set of chosen parameters.
+function make_cartesian_product(parms, callback)
+	return make_cartesian_product_internal(parms, callback, 1, {})
+end
+
+function make_cartesian_product_internal(parms, callback, index, args)
+	if index > #parms then
+		return callback(unpack(args))
+	end
+	local ret = {}
+	for _, value in ipairs(parms[index]) do
+		args[index] = value
+		ret[value] = make_cartesian_product_internal(parms, callback, index + 1, args)
+	end
+	return ret
+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 resample_effect = nil
+	local resize_effect = nil
+	if (hq) then
+		resample_effect = chain:add_effect(ResampleEffect.new())
+	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())
+
+	return {
+		input = input,
+		wb_effect = wb_effect,
+		resample_effect = resample_effect,
+		resize_effect = resize_effect,
+		padding_effect = padding_effect
+	}
+end
+
+-- The main live chain.
+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_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)
+
+	chain:add_effect(OverlayEffect.new(), input0.padding_effect, input1.padding_effect)
+	chain:finalize(hq)
+
+	return {
+		chain = chain,
+		input0 = input0,
+		input1 = input1
+	}
+end
+
+-- Make all possible combinations of side-by-side chains.
+local sbs_chains = make_cartesian_product({
+	{"live", "livedeint"},  -- input0_type
+	{"live", "livedeint"},  -- input1_type
+	{true, false}           -- hq
+}, function(input0_type, input1_type, 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)
+		input:connect_signal(signal)
+		last = input
+	else
+		input = chain:add_effect(ImageInput.new("bg.jpeg"))
+		last = input
+	end
+
+	-- If we cared about this for the non-main inputs, we would have
+	-- checked hq here and invoked ResizeEffect instead.
+	if scale then
+		resample_effect = chain:add_effect(ResampleEffect.new())
+		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,
+		resample_effect = resample_effect,
+		last = last
+	}
+end
+
+-- A chain to fade between two inputs, of which either can be a picture
+-- or a live input. In practice only used live, but we still support the
+-- hq parameter.
+function make_fade_chain(input0_live, input0_deint, input0_scale, input1_live, input1_deint, input1_scale, hq)
+	local chain = EffectChain.new(16, 9)
+
+	local input0 = make_fade_input(chain, INPUT0_SIGNAL_NUM, input0_live, input0_deint, input0_scale)
+	local input1 = make_fade_input(chain, INPUT1_SIGNAL_NUM, input1_live, input1_deint, input1_scale)
+
+	local mix_effect = chain:add_effect(MixEffect.new(), input0.last, input1.last)
+	chain:finalize(hq)
+
+	return {
+		chain = chain,
+		input0 = input0,
+		input1 = input1,
+		mix_effect = mix_effect
+	}
+end
+
+-- Chains to fade between two inputs, in various configurations.
+local fade_chains = make_cartesian_product({
+	{"static", "live", "livedeint"},  -- input0_type
+	{true, false},                    -- input0_scale
+	{"static", "live", "livedeint"},  -- input1_type
+	{true, false},                    -- input1_scale
+	{true}                            -- hq
+}, function(input0_type, input0_scale, input1_type, input1_scale, hq)
+	local input0_live = (input0_type ~= "static")
+	local input1_live = (input1_type ~= "static")
+	local input0_deint = (input0_type == "livedeint")
+	local input1_deint = (input1_type == "livedeint")
+	return make_fade_chain(input0_live, input0_deint, input0_scale, input1_live, input1_deint, input1_scale, hq)
+end)
 
 -- A chain to show a single input on screen.
-local simple_chain = EffectChain.new(16, 9);
-local simple_chain_input = simple_chain:add_live_input();
-simple_chain_input:connect_signal(0);  -- First input card. Can be changed whenever you want.
-simple_chain:finalize(false);
+function make_simple_chain(input_deint, input_scale, hq)
+	local chain = EffectChain.new(16, 9)
 
+	local input = chain:add_live_input(false, input_deint)
+	input:connect_signal(0)  -- First input card. Can be changed whenever you want.
+
+	local resample_effect, resize_effect
+	if scale then
+		if hq then
+			resample_effect = chain:add_effect(ResampleEffect.new())
+		else
+			resize_effect = chain:add_effect(ResizeEffect.new())
+		end
+	end
+
+	local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
+	chain:finalize(hq)
+
+	return {
+		chain = chain,
+		input = input,
+		wb_effect = wb_effect,
+		resample_effect = resample_effect,
+		resize_effect = resize_effect
+	}
+end
+
+-- Make all possible combinations of single-input chains.
+local simple_chains = make_cartesian_product({
+	{"live", "livedeint"},  -- input_type
+	{true, false},          -- input_scale
+	{true, false}           -- hq
+}, function(input_type, input_scale, hq)
+	local input_deint = (input_type == "livedeint")
+	return make_simple_chain(input_deint, input_scale, hq)
+end)
+
+-- A chain to show a single static picture on screen (HQ version).
+local static_chain_hq = EffectChain.new(16, 9)
+local static_chain_hq_input = static_chain_hq:add_effect(ImageInput.new("bg.jpeg"))
+static_chain_hq:finalize(true)
+
+-- A chain to show a single static picture on screen (LQ version).
+local static_chain_lq = EffectChain.new(16, 9)
+local static_chain_lq_input = static_chain_lq:add_effect(ImageInput.new("bg.jpeg"))
+static_chain_lq:finalize(false)
+
+-- Used for indexing into the tables of chains.
+function get_input_type(signals, signal_num)
+	if signal_num == STATIC_SIGNAL_NUM then
+		return "static"
+	elseif signals:get_interlaced(signal_num) then
+		return "livedeint"
+	else
+		return "live"
+	end
+end
+
+function needs_scale(signals, signal_num, width, height)
+	if signal_num == STATIC_SIGNAL_NUM then
+		-- We assume this is already correctly scaled at load time.
+		return false
+	end
+	assert(is_plain_signal(signal_num))
+	return (signals:get_width(signal_num) ~= width or signals:get_height(signal_num) ~= height)
+end
+
+function set_scale_parameters_if_needed(chain_or_input, width, height)
+	if chain_or_input.resample_effect then
+		chain_or_input.resample_effect:set_int("width", width)
+		chain_or_input.resample_effect:set_int("height", height)
+	elseif chain_or_input.resize_effect then
+		chain_or_input.resize_effect:set_int("width", width)
+		chain_or_input.resize_effect:set_int("height", height)
+	end
+end
+
+-- API ENTRY POINT
 -- Returns the number of outputs in addition to the live (0) and preview (1).
 -- Called only once, at the start of the program.
 function num_channels()
-	return 2;
+	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)
+	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(res)
+	local nom = res.frame_rate_nom
+	local den = res.frame_rate_den
+	if nom % den == 0 then
+		return nom / den
+	else
+		return string.format("%.2f", nom / den)
+	end
+end
+
+-- Helper function to write e.g. “720p60”.
+function get_channel_resolution_raw(res)
+	if res.interlaced then
+		return res.height .. "i" .. get_frame_rate(res)
+	else
+		return res.height .. "p" .. get_frame_rate(res)
+	end
+end
+
+-- API ENTRY POINT
+-- Returns the name for each additional channel (starting from 2).
+-- Called at the start of the program, and then each frame for live
+-- channels in case they change resolution.
+function channel_name(channel)
+	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 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.
+-- (The information is used for whether right-click on the channel should bring up
+-- an input selector or not.)
+-- 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)
+	if channel == 2 then
+		return 0
+	elseif channel == 3 then
+		return 1
+	else
+		return -1
+	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 transition_type ~= NO_TRANSITION then
+		if channel_involved_in(channel, transition_src_signal) or
+		   channel_involved_in(channel, transition_dst_signal) then
+			return "#f00"
+		end
+	else
+		if channel_involved_in(channel, live_signal_num) then
+			return "#f00"
+		end
+	end
+	if channel_involved_in(channel, 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 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 is_plain_signal(channel - 2) then
+		neutral_colors[channel - 2 + 1] = { red, green, blue }
+	end
+end
+
+function finish_transitions(t)
+	if transition_type ~= NO_TRANSITION and t >= transition_end then
+		live_signal_num = transition_dst_signal
+		transition_type = NO_TRANSITION
+	end
+end
+
+function in_transition(t)
+       return t >= transition_start and t <= transition_end
 end
 
+-- API ENTRY POINT
 -- Called every frame.
-function get_transitions()
-	return {"Cut", "Fade", "Zoom!"};
+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
+		-- No transitions possible.
+		return {}
+	end
+
+	if (is_plain_signal(live_signal_num) or live_signal_num == STATIC_SIGNAL_NUM) and
+	   (is_plain_signal(preview_signal_num) or preview_signal_num == STATIC_SIGNAL_NUM) then
+		return {"Cut", "", "Fade"}
+	end
+
+	-- Various zooms.
+	if live_signal_num == SBS_SIGNAL_NUM and is_plain_signal(preview_signal_num) then
+		return {"Cut", "Zoom in"}
+	elseif is_plain_signal(live_signal_num) and preview_signal_num == SBS_SIGNAL_NUM then
+		return {"Cut", "Zoom out"}
+	end
+
+	return {"Cut"}
+end
+
+function swap_preview_live()
+	local temp = live_signal_num
+	live_signal_num = preview_signal_num
+	preview_signal_num = temp
+end
+
+function start_transition(type_, t, duration)
+	transition_start = t
+	transition_end = t + duration
+	transition_type = type_
+	transition_src_signal = live_signal_num
+	transition_dst_signal = preview_signal_num
+	swap_preview_live()
 end
 
+-- API ENTRY POINT
+-- Called when the user clicks a transition button.
 function transition_clicked(num, t)
-	-- Only a cut for now.
-	local temp = live_signal_num;
-	live_signal_num = preview_signal_num;
-	preview_signal_num = temp;
+	if num == 0 then
+		-- Cut.
+		if in_transition(t) then
+			-- Ongoing transition; finish it immediately before the cut.
+			finish_transitions(transition_end)
+		end
+
+		swap_preview_live()
+	elseif num == 1 then
+		-- Zoom.
+		finish_transitions(t)
+
+		if live_signal_num == preview_signal_num then
+			-- Nothing to do.
+			return
+		end
+
+		if is_plain_signal(live_signal_num) and is_plain_signal(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")
+			swap_preview_live()
+			return
+		end
+
+		if (live_signal_num == SBS_SIGNAL_NUM and is_plain_signal(preview_signal_num)) or
+		   (preview_signal_num == SBS_SIGNAL_NUM and is_plain_signal(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
+		   (is_plain_signal(live_signal_num) or
+		    live_signal_num == STATIC_SIGNAL_NUM) and
+		   (is_plain_signal(preview_signal_num) or
+		    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
+	end
 end
 
-function channel_clicked(num, t)
-	-- Presumably change the preview here.
-	io.write("STUB: channel_clicked\n");
+-- API ENTRY POINT
+function channel_clicked(num)
+	preview_signal_num = num
 end
 
+function get_fade_chain(signals, t, width, height, input_resolution)
+	local input0_type = get_input_type(signals, transition_src_signal)
+	local input0_scale = needs_scale(signals, transition_src_signal, width, height)
+	local input1_type = get_input_type(signals, transition_dst_signal)
+	local input1_scale = needs_scale(signals, transition_dst_signal, width, height)
+	local chain = fade_chains[input0_type][input0_scale][input1_type][input1_scale][true]
+	prepare = function()
+		if input0_type == "live" or input0_type == "livedeint" then
+			chain.input0.input:connect_signal(transition_src_signal)
+			set_neutral_color_from_signal(chain.input0.wb_effect, 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(transition_dst_signal)
+			set_neutral_color_from_signal(chain.input1.wb_effect, transition_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)
+	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
 -- Called every frame. Get the chain for displaying at input <num>,
 -- where 0 is live, 1 is preview, 2 is the first channel to display
--- in the bottom bar, and so on up to num_channels()+1. t is the 
+-- in the bottom bar, and so on up to num_channels()+1. t is the
 -- current time in seconds. width and height are the dimensions of
 -- the output, although you can ignore them if you don't need them
 -- (they're useful if you want to e.g. know what to resample by).
+--
+-- <signals> is basically an exposed InputState, which you can use to
+-- query for information about the signals at the point of the current
+-- frame. In particular, you can call get_width() and get_height()
+-- for any signal number, and use that to e.g. assist in chain selection.
+--
+-- You should return two objects; the chain itself, and then a
+-- function (taking no parameters) that is run just before rendering.
+-- The function needs to call connect_signal on any inputs, so that
+-- it gets updated video data for the given frame. (You are allowed
+-- to switch which input your input is getting from between frames,
+-- but not calling connect_signal results in undefined behavior.)
 -- If you want to change any parameters in the chain, this is also
 -- the right place.
 --
 -- NOTE: The chain returned must be finalized with the Y'CbCr flag
 -- if and only if num==0.
-function get_chain(num, t, width, height)
+function get_chain(num, t, width, height, signals)
+	local input_resolution = {}
+	for signal_num=0,1 do
+		local res = {
+			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)
+		}
+
+		if res.interlaced then
+			-- Convert height from frame height to field height.
+			-- (Needed for e.g. place_rectangle.)
+			res.height = res.height * 2
+
+			-- Show field rate instead of frame rate; really for cosmetics only
+			-- (and actually contrary to EBU recommendations, although in line
+			-- with typical user expectations).
+			res.frame_rate_nom = res.frame_rate_nom * 2
+		end
+
+		input_resolution[signal_num] = res
+	end
+	last_resolution = input_resolution
+
 	if num == 0 then  -- Live.
-		prepare = function()
-			input0:connect_signal(live_signal_num);
-			wb_effect:set_float("output_color_temperature", 3500.0 + t * 100.0);
+		finish_transitions(t)
+		if transition_type == ZOOM_TRANSITION then
+			-- Transition in or out of SBS.
+			local chain = get_sbs_chain(signals, t, width, height, input_resolution)
+			prepare = function()
+				prepare_sbs_chain(chain, calc_zoom_progress(t), transition_type, transition_src_signal, transition_dst_signal, width, height, input_resolution)
+			end
+			return chain.chain, prepare
+		elseif transition_type == NO_TRANSITION and live_signal_num == SBS_SIGNAL_NUM then
+			-- Static SBS view.
+			local chain = get_sbs_chain(signals, t, width, height, input_resolution)
+			prepare = function()
+				prepare_sbs_chain(chain, 0.0, NO_TRANSITION, 0, SBS_SIGNAL_NUM, width, height, input_resolution)
+			end
+			return chain.chain, prepare
+		elseif transition_type == FADE_TRANSITION then
+			return get_fade_chain(signals, t, width, height, input_resolution)
+		elseif is_plain_signal(live_signal_num) then
+			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)
+			end
+			return chain.chain, prepare
+		elseif live_signal_num == STATIC_SIGNAL_NUM then  -- Static picture.
+			prepare = function()
+			end
+			return static_chain_hq, prepare
+		else
+			assert(false)
 		end
-		return main_chain, prepare;
 	end
 	if num == 1 then  -- Preview.
+		num = preview_signal_num + 2
+	end
+
+	-- Individual preview inputs.
+	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()
-			simple_chain_input:connect_signal(preview_signal_num);
+			chain.input:connect_signal(signal_num)
+			set_scale_parameters_if_needed(chain, width, height)
+			set_neutral_color(chain.wb_effect, neutral_colors[signal_num + 1])
 		end
-		return simple_chain, prepare;
+		return chain.chain, prepare
 	end
-	if num == 2 then
+	if num == SBS_SIGNAL_NUM + 2 then
+		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()
-			simple_chain_input:connect_signal(0);
+			prepare_sbs_chain(chain, 0.0, NO_TRANSITION, 0, SBS_SIGNAL_NUM, width, height, input_resolution)
 		end
-		return simple_chain, prepare;
+		return chain.chain, prepare
 	end
-	if num == 3 then
+	if num == STATIC_SIGNAL_NUM + 2 then
 		prepare = function()
-			simple_chain_input:connect_signal(1);
 		end
-		return simple_chain, prepare;
+		return static_chain_lq, prepare
+	end
+end
+
+function place_rectangle(resample_effect, resize_effect, padding_effect, x0, y0, x1, y1, screen_width, screen_height, input_width, input_height)
+	local srcx0 = 0.0
+	local srcx1 = 1.0
+	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
+		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
+	end
+
+	-- Clip.
+	if x0 < 0 then
+		srcx0 = -x0 / (x1 - x0)
+		x0 = 0
+	end
+	if y0 < 0 then
+		srcy0 = -y0 / (y1 - y0)
+		y0 = 0
+	end
+	if x1 > screen_width then
+		srcx1 = (screen_width - x0) / (x1 - x0)
+		x1 = screen_width
+	end
+	if y1 > screen_height then
+		srcy1 = (screen_height - y0) / (y1 - y0)
+		y1 = screen_height
+	end
+
+	if resample_effect ~= nil then
+		-- High-quality resampling.
+		local x_subpixel_offset = x0 - math.floor(x0)
+		local y_subpixel_offset = y0 - math.floor(y0)
+
+		-- Resampling must be to an integral number of pixels. Round up,
+		-- and then add an extra pixel so we have some leeway for the border.
+		local width = math.ceil(x1 - x0) + 1
+		local height = math.ceil(y1 - y0) + 1
+		resample_effect:set_int("width", width)
+		resample_effect:set_int("height", height)
+
+		-- Correct the discrepancy with zoom. (This will leave a small
+		-- excess edge of pixels and subpixels, which we'll correct for soon.)
+		local zoom_x = (x1 - x0) / (width * (srcx1 - srcx0))
+		local zoom_y = (y1 - y0) / (height * (srcy1 - srcy0))
+		resample_effect:set_float("zoom_x", zoom_x)
+		resample_effect:set_float("zoom_y", zoom_y)
+		resample_effect:set_float("zoom_center_x", 0.0)
+		resample_effect:set_float("zoom_center_y", 0.0)
+
+		-- Padding must also be to a whole-pixel offset.
+		padding_effect:set_int("left", math.floor(x0))
+		padding_effect:set_int("top", math.floor(y0))
+
+		-- Correct _that_ discrepancy by subpixel offset in the resampling.
+		resample_effect:set_float("left", srcx0 * input_width - x_subpixel_offset / zoom_x)
+		resample_effect:set_float("top", srcy0 * input_height - y_subpixel_offset / zoom_y)
+
+		-- Finally, adjust the border so it is exactly where we want it.
+		padding_effect:set_float("border_offset_left", x_subpixel_offset)
+		padding_effect:set_float("border_offset_right", x1 - (math.floor(x0) + width))
+		padding_effect:set_float("border_offset_top", y_subpixel_offset)
+		padding_effect:set_float("border_offset_bottom", y1 - (math.floor(y0) + height))
+	else
+		-- Lower-quality simple resizing.
+		local width = round(x1 - x0)
+		local height = round(y1 - y0)
+		resize_effect:set_int("width", width)
+		resize_effect:set_int("height", height)
+
+		-- Padding must also be to a whole-pixel offset.
+		padding_effect:set_int("left", math.floor(x0))
+		padding_effect:set_int("top", math.floor(y0))
+	end
+end
+
+-- This is broken, of course (even for positive numbers), but Lua doesn't give us access to real rounding.
+function round(x)
+	return math.floor(x + 0.5)
+end
+
+function lerp(a, b, t)
+	return a + (b - a) * t
+end
+
+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(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, neutral_colors[1])
+	set_neutral_color(chain.input1.wb_effect, neutral_colors[2])
+
+	-- First input is positioned (16,48) from top-left.
+	-- Second input is positioned (16,48) from the bottom-right.
+	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
+		-- 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
+
+		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
+
+	-- 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
+
+-- 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 is_plain_signal(signal) then
+		set_neutral_color(effect, neutral_colors[signal - INPUT0_SIGNAL_NUM + 1])
+	end
+end
+
+function calc_zoom_progress(t)
+	if t < transition_start then
+		return 0.0
+	elseif t > transition_end then
+		return 1.0
+	else
+		local tt = (t - transition_start) / (transition_end - 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
+		return 0.0
+	elseif tt > 1.0 then
+		return 1.0
+	end
+
+	-- Make the fade look maybe a tad more natural, by pumping it
+	-- through a sigmoid function.
+	tt = 10.0 * tt - 5.0
+	tt = 1.0 / (1.0 + math.exp(-tt))
+
+	return tt
+end