Move to integer based thumbnail state list, fix indices

Also, adjust progress block rendering to display the proper size,
so that the last block will be partial.
This way thumbnail ranges are displayed more accurately, useful for
development.

Author: TheAMM

src/patched_osc.lua

@@ -163,16 +163,17 @@ function display_thumbnail(pos, value, ass)
             ass:append(("%d%% - %d/%d"):format(perc, thumbs_ready, thumbs_total))
 
             -- Draw the generation progress
-            local block_w = (thumb_size.w / thumbs_total) * msy
+            local block_w = thumb_size.w * (Thumbnailer.state.thumbnail_delta / duration) * msy
+            local block_max_x = thumb_size.w * msy
 
             -- Draw finished thumbnail blocks (white)
             ass:new_event()
             ass:pos(bg_left, framegraph_top)
             ass:append(("{\\bord0\\1c&HFFFFFF&\\1a&H%X&"):format(0))
             ass:draw_start(2)
             for i, v in pairs(Thumbnailer.state.thumbnails) do
-                if i ~= closest_index and v then
-                    ass:rect_cw(i*block_w, 0, (i+1)*block_w, framegraph_h)
+                if i ~= closest_index and v > 0 then
+                    ass:rect_cw((i-1)*block_w, 0, math.min(block_max_x, i*block_w), framegraph_h)
                 end
             end
             ass:draw_stop()
@@ -183,8 +184,8 @@ function display_thumbnail(pos, value, ass)
             ass:append(("{\\bord0\\1c&H44AA44&\\1a&H%X&"):format(0))
             ass:draw_start(2)
             for i, v in pairs(Thumbnailer.state.thumbnails) do
-                if i ~= closest_index and v == false then
-                    ass:rect_cw(i*block_w, 0, (i+1)*block_w, framegraph_h)
+                if i ~= closest_index and v == 0 then
+                    ass:rect_cw((i-1)*block_w, 0, math.min(block_max_x, i*block_w), framegraph_h)
                 end
             end
             ass:draw_stop()
@@ -194,7 +195,7 @@ function display_thumbnail(pos, value, ass)
                 ass:pos(bg_left, framegraph_top)
                 ass:append(("{\\bord0\\1c&H4444FF&\\1a&H%X&"):format(0))
                 ass:draw_start(2)
-                ass:rect_cw(closest_index*block_w, 0, (closest_index+1)*block_w, framegraph_h)
+                ass:rect_cw((closest_index-1)*block_w, 0, math.min(block_max_x, closest_index*block_w), framegraph_h)
                 ass:draw_stop()
             end
         end

src/thumbnailer_server.lua

@@ -175,8 +175,10 @@ function do_worker_job(state_json_string, frames_json_string)
     end
 
     local generate_thumbnail_for_index = function(thumbnail_index)
-        local thumbnail_path = thumb_state.thumbnail_template:format(thumbnail_index)
-        local timestamp = math.min(file_duration, thumbnail_index * thumb_state.thumbnail_delta)
+        -- Given a 1-based thumbnail index, generate a thumbnail for it based on the thumbnailer state
+
+        local thumbnail_path = thumb_state.thumbnail_template:format(thumbnail_index - 1)
+        local timestamp = math.min(file_duration, (thumbnail_index - 1) * thumb_state.thumbnail_delta)
 
         mp.commandv("script-message", "mpv_thumbnail_script-progress", tostring(thumbnail_index))
 
@@ -193,7 +195,7 @@ function do_worker_job(state_json_string, frames_json_string)
             local existing_thumbnail_filesize = thumbnail_file:seek("end")
             if existing_thumbnail_filesize ~= thumbnail_raw_size then
                 -- Size doesn't match, so (re)generate
-                msg.warn("Thumbnail", thumbnail_index, "did not match expected size, regenerating")
+                msg.warn("Thumbnail", thumbnail_index-1, "did not match expected size, regenerating")
                 need_thumbnail_generation = true
             end
             thumbnail_file:close()

src/thumbnailer_shared.lua

@@ -14,6 +14,11 @@ local Thumbnailer = {
         thumbnail_size = nil,
 
         finished_thumbnails = 0,
+
+        -- List of thumbnail states (from 1 to thumbnail_count)
+        -- ready: 1
+        -- in progress: 0
+        -- not ready: -1
         thumbnails = {}
     },
     workers = {}
@@ -33,17 +38,19 @@ function Thumbnailer:on_file_loaded()
 end
 
 function Thumbnailer:on_thumb_ready(index)
-    self.state.thumbnails[index] = true
+    self.state.thumbnails[index] = 1
 
-    -- Recount (just in case)
+    -- Full recount instead of a naive increment (let's be safe!)
     self.state.finished_thumbnails = 0
-    for i in pairs(self.state.thumbnails) do
-        self.state.finished_thumbnails = self.state.finished_thumbnails + 1
+    for i, v in pairs(self.state.thumbnails) do
+        if v > 0 then
+            self.state.finished_thumbnails = self.state.finished_thumbnails + 1
+        end
     end
 end
 
 function Thumbnailer:on_thumb_progress(index)
-    self.state.thumbnails[index] = self.state.thumbnails[index] or false
+    self.state.thumbnails[index] = math.max(self.state.thumbnails[index], 0)
 end
 
 function Thumbnailer:on_video_change(params)
@@ -58,7 +65,12 @@ end
 
 function Thumbnailer:update_state()
     self.state.thumbnail_delta = self:get_delta()
-    self.state.thumbnail_count = self:get_thumbnail_count()
+    self.state.thumbnail_count = self:get_thumbnail_count(self.state.thumbnail_delta)
+
+    -- Prefill individual thumbnail states
+    for i = 1, self.state.thumbnail_count do
+        self.state.thumbnails[i] = -1
+    end
 
     self.state.thumbnail_template = self:get_thumbnail_template()
     self.state.thumbnail_size = self:get_thumbnail_size()
@@ -165,8 +177,7 @@ function Thumbnailer:get_delta()
 end
 
 
-function Thumbnailer:get_thumbnail_count()
-    local delta = self:get_delta()
+function Thumbnailer:get_thumbnail_count(delta)
     if delta == nil then
         return 0
     end
@@ -176,26 +187,50 @@ function Thumbnailer:get_thumbnail_count()
 end
 
 function Thumbnailer:get_closest(thumbnail_index)
-    local min_distance = self.state.thumbnail_count+1
+    -- Given a 1-based index, find the closest available thumbnail and return it's 1-based index
+
+    -- Check the direct thumbnail index first
+    if self.state.thumbnails[thumbnail_index] > 0 then
+        return thumbnail_index
+    end
+
+    local min_distance = self.state.thumbnail_count + 1
     local closest = nil
 
+    -- Naive, inefficient, lazy. But functional.
     for index, value in pairs(self.state.thumbnails) do
         local distance = math.abs(index - thumbnail_index)
-        if distance < min_distance and value then
+        if distance < min_distance and value > 0 then
             min_distance = distance
             closest = index
         end
     end
-    return closest, min_distance
+    return closest
+end
+
+function Thumbnailer:get_thumbnail_index(time_position)
+    -- Returns a 1-based thumbnail index for the given timestamp (between 1 and thumbnail_count, inclusive)
+    if self.state.thumbnail_delta and (self.state.thumbnail_count and self.state.thumbnail_count > 0) then
+        return math.min(math.floor(time_position / self.state.thumbnail_delta) + 1, self.state.thumbnail_count)
+    else
+        return nil
+    end
 end
 
 function Thumbnailer:get_thumbnail_path(time_position)
-    local thumbnail_index = math.min(math.floor(time_position / self.state.thumbnail_delta), self.state.thumbnail_count-1)
+    -- Given a timestamp, return:
+    --   the closest available thumbnail path (if any)
+    --   the 1-based thumbnail index calculated from the timestamp
+    --   the 1-based thumbnail index of the closest available (and used) thumbnail
+    -- OR nil if thumbnails are not available.
+
+    local thumbnail_index = self:get_thumbnail_index(time_position)
+    if not thumbnail_index then return nil end
 
-    local closest, distance = self:get_closest(thumbnail_index)
+    local closest = self:get_closest(thumbnail_index)
 
     if closest ~= nil then
-        return self.state.thumbnail_template:format(closest), thumbnail_index, closest
+        return self.state.thumbnail_template:format(closest-1), thumbnail_index, closest
     else
         return nil, thumbnail_index, nil
     end
@@ -243,13 +278,16 @@ function Thumbnailer:register_client()
 end
 
 function Thumbnailer:_create_thumbnail_job_order()
+    -- Returns a list of 1-based thumbnail indices in a job order
     local used_frames = {}
     local work_frames = {}
 
+    -- Pick frames in increasing frequency.
+    -- This way we can do a quick few passes over the video and then fill in the gaps.
     for x = 6, 0, -1 do
         local nth = (2^x)
 
-        for thi = 0, self.state.thumbnail_count-1, nth do
+        for thi = 1, self.state.thumbnail_count, nth do
             if not used_frames[thi] then
                 table.insert(work_frames, thi)
                 used_frames[thi] = true