]> git.sesse.net Git - nageru/blobdiff - theme.lua
Write 1.4.0 changelog.
[nageru] / theme.lua
index 514cb03f0c61196e87c8ec6a7989e99212fa1b5f..77a1ff15cde855daf459367af3be3adc764d77d4 100644 (file)
--- a/theme.lua
+++ b/theme.lua
 -- 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 zoom_start = -2.0
-local zoom_end = -1.0
-local zoom_src = 0.0
-local zoom_dst = 1.0
+local transition_start = -2.0
+local transition_end = -1.0
+local transition_type = 0
+local transition_src_signal = 0
+local transition_dst_signal = 0
+
+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.
-local main_chain = EffectChain.new(16, 9)
-local input0 = main_chain:add_live_input()
-input0:connect_signal(0)
-local input1 = main_chain:add_live_input()
-input1:connect_signal(1)
-local resample_effect = main_chain:add_effect(ResampleEffect.new(), input0)
-local padding_effect = main_chain:add_effect(IntegralPaddingEffect.new())
-padding_effect:set_vec4("border_color", 0.0, 0.0, 0.0, 1.0)
-
-local resample2_effect = main_chain:add_effect(ResampleEffect.new(), input1)
--- Effect *saturation_effect = main_chain->add_effect(new SaturationEffect())
--- CHECK(saturation_effect->set_float("saturation", 0.3f))
-local wb_effect = main_chain:add_effect(WhiteBalanceEffect.new())
-wb_effect:set_float("output_color_temperature", 3500.0)
-local padding2_effect = main_chain:add_effect(IntegralPaddingEffect.new())
-
-main_chain:add_effect(OverlayEffect.new(), padding_effect, padding2_effect)
-main_chain:finalize(true)
-
--- A chain to show a single input on screen (HQ version).
-local simple_chain_hq = EffectChain.new(16, 9)
-local simple_chain_hq_input = simple_chain_hq:add_live_input()
-simple_chain_hq_input:connect_signal(0);  -- First input card. Can be changed whenever you want.
-simple_chain_hq:finalize(true)
-
--- A chain to show a single input on screen (LQ version).
-local simple_chain_lq = EffectChain.new(16, 9)
-local simple_chain_lq_input = simple_chain_lq:add_live_input()
-simple_chain_lq_input:connect_signal(0);  -- First input card. Can be changed whenever you want.
-simple_chain_lq:finalize(false)
+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.
+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)
-       -- 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
 
-       zoom_start = t
-       zoom_end = t + 1.0
+               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
 
-       local temp = zoom_src
-       zoom_src = zoom_dst
-       zoom_dst = temp
+-- 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
 
-function channel_clicked(num, t)
-       -- Presumably change the preview here.
-       io.write("STUB: channel_clicked\n")
+-- 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
@@ -95,67 +554,137 @@ end
 --
 -- 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.
-               if t > zoom_end and zoom_dst == 1.0 then
-                       -- Special case: Show only the single image on screen.
+               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()
-                               simple_chain_hq_input:connect_signal(live_signal_num)
+                               prepare_sbs_chain(chain, calc_zoom_progress(t), transition_type, transition_src_signal, transition_dst_signal, width, height, input_resolution)
                        end
-                       return simple_chain_hq, prepare
-               end
-               prepare = function()
-                       if t < zoom_start then
-                               prepare_sbs_chain(zoom_src, width, height)
-                       elseif t > zoom_end then
-                               prepare_sbs_chain(zoom_dst, width, height)
-                       else
-                               local tt = (t - zoom_start) / (zoom_end - zoom_start)
-                               -- Smooth it a bit.
-                               tt = math.sin(tt * 3.14159265358 * 0.5)
-                               prepare_sbs_chain(zoom_src + (zoom_dst - zoom_src) * tt, width, height)
+                       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_lq_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_lq, 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_lq_input:connect_signal(0)
+                       prepare_sbs_chain(chain, 0.0, NO_TRANSITION, 0, SBS_SIGNAL_NUM, width, height, input_resolution)
                end
-               return simple_chain_lq, prepare
+               return chain.chain, prepare
        end
-       if num == 3 then
+       if num == STATIC_SIGNAL_NUM + 2 then
                prepare = function()
-                       simple_chain_lq_input:connect_signal(1)
                end
-               return simple_chain_lq, prepare
+               return static_chain_lq, prepare
        end
 end
 
-function place_rectangle(resample_effect, padding_effect, x0, y0, x1, y1, screen_width, screen_height)
+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
-               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
        end
 
-       -- Clip. (TODO: Clip on upper/left sides, too.)
+       -- 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
@@ -165,81 +694,178 @@ function place_rectangle(resample_effect, padding_effect, x0, y0, x1, y1, screen
                y1 = screen_height
        end
 
-       local x_subpixel_offset = x0 - math.floor(x0)
-       local y_subpixel_offset = y0 - math.floor(y0)
+       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
 
-       -- 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)
+-- 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
 
-       -- 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)
+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
 
-       -- 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))
+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
 
-       -- Correct _that_ discrepancy by subpixel offset in the resampling.
-       resample_effect:set_float("left", -x_subpixel_offset / zoom_x)
-       resample_effect:set_float("top", -y_subpixel_offset / zoom_y)
+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])
 
-       -- 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))
+       -- 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
 
--- 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)
+-- 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 prepare_sbs_chain(t, screen_width, screen_height)
-       input0:connect_signal(live_signal_num)
-       input1:connect_signal(1)
+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
 
-       -- 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)
+       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
 
-       local top0 = 48 * screen_height/720.0
-       local left0 = 16 * screen_width/1280.0
-       local bottom0 = top0 + height0
-       local right0 = left0 + width0
+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
 
-       -- Second input is positioned (16,48) from the bottom-right.
-       local width1 = 384 * screen_width/1280.0
-       local height1 = 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 = 1.0 + t * (1280.0 / 848.0 - 1.0)
-       local tx0 = 0.0 + t * (-left0 * scale0)
-       local ty0 = 0.0 + t * (-top0 * scale0)
-
-       top0 = top0 * scale0 + ty0
-       bottom0 = bottom0 * scale0 + ty0
-       left0 = left0 * scale0 + tx0
-       right0 = right0 * scale0 + tx0
-
-       top1 = top1 * scale0 + ty0
-       bottom1 = bottom1 * scale0 + ty0
-       left1 = left1 * scale0 + tx0
-       right1 = right1 * scale0 + tx0
-       place_rectangle(resample_effect, padding_effect, left0, top0, right0, bottom0, screen_width, screen_height)
-       place_rectangle(resample2_effect, padding2_effect, left1, top1, right1, bottom1, screen_width, screen_height)
+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