allow upscaling storyboards

src/options.lua

@@ -123,6 +123,8 @@ local thumbnailer_options = {
     storyboard_enable = true,
     -- Max thumbnails for storyboards. It only skips processing some of the downloaded thumbnails and doesn't make it much faster
     storyboard_max_thumbnail_count = 800,
+    -- Most storyboard thumbnails are 160x90. Enabling this allows upscaling them up to thumbnail_height
+    storyboard_upscale = false,
 }
 
 read_options(thumbnailer_options, SCRIPT_NAME)

src/thumbnailer_server.lua

@@ -55,7 +55,9 @@ function create_thumbnail_mpv(file_path, timestamp, size, output_path, options)
         -- Optionally disable subtitles
         (thumbnailer_options.mpv_no_sub and "--no-sub" or nil),
 
-        (options.no_scale == nil and ("--vf=scale=%d:%d"):format(size.w, size.h) or nil),
+        (options.relative_scale == nil
+                and ("--vf=scale=%d:%d"):format(size.w, size.h)
+                or ("--vf=scale=iw*%d:ih*%d"):format(size.w, size.h)),
 
         "--vf-add=format=bgra",
         "--of=rawvideo",
@@ -69,7 +71,7 @@ end
 function create_thumbnail_ffmpeg(file_path, timestamp, size, output_path, options)
     options = options or {}
 
-    local ffmpeg_command = skip_nil({
+    local ffmpeg_command = {
         "ffmpeg",
         "-loglevel", "quiet",
         "-noaccurate_seek",
@@ -79,13 +81,17 @@ function create_thumbnail_ffmpeg(file_path, timestamp, size, output_path, option
         "-frames:v", "1",
         "-an",
 
-        (options.no_scale == nil and "-vf" or nil), (options.no_scale == nil and ("scale=%d:%d"):format(size.w, size.h) or nil),
+        "-vf",
+        (options.relative_scale == nil
+                and ("scale=%d:%d"):format(size.w, size.h)
+                or ("scale=iw*%d:ih*%d"):format(size.w, size.h)),
+
         "-c:v", "rawvideo",
         "-pix_fmt", "bgra",
         "-f", "rawvideo",
 
         "-y", output_path
-    })
+    }
     return utils.subprocess({args=ffmpeg_command})
 end
 
@@ -225,7 +231,7 @@ function do_worker_job(state_json_string, frames_json_string)
                 if url == nil then
                     url = thumb_state.storyboard.fragment_base_url .. "/" .. thumb_state.storyboard.fragments[atlas_idx+1].path
                 end
-                local ret = thumbnail_func(url, 0, thumb_state.thumbnail_size, atlas_path, { no_scale=true })
+                local ret = thumbnail_func(url, 0, { w=thumb_state.storyboard.scale, h=thumb_state.storyboard.scale }, atlas_path, { relative_scale=true })
                 success = check_output(ret, atlas_path, thumbnail_func == create_thumbnail_mpv)
                 if success then
                     split_atlas(atlas_path, cols, thumb_state.thumbnail_size, function(idx)

src/thumbnailer_shared.lua

@@ -108,7 +108,7 @@ function Thumbnailer:check_storyboard_async(callback)
                     self.state.storyboard.fragment_base_url = sb.fragment_base_url
                     self.state.storyboard.rows = sb.rows or 5
                     self.state.storyboard.cols = sb.columns or 5
-                    self.state.thumbnail_size = {w=sb.width, h=sb.height}
+
                     if sb.fps then
                         self.state.thumbnail_count = math.floor(sb.fps * sb.duration + 0.5) -- round
                         -- hack: youtube always adds 1 black frame at the end...
@@ -122,6 +122,16 @@ function Thumbnailer:check_storyboard_async(callback)
                         self.state.thumbnail_count = math.floor(sb.duration / self.state.thumbnail_delta)
                     end
 
+                    -- Storyboard upscaling factor
+                    local scale = 1
+                    if thumbnailer_options.storyboard_upscale then
+                        -- BUG: sometimes mpv crashes when asked for non-integer scaling and BGRA format (something related to zimg?)
+                        -- use integer scaling for now
+                        scale = math.max(1, math.floor(thumbnailer_options.thumbnail_height / sb.height))
+                    end
+                    self.state.thumbnail_size = {w=sb.width*scale, h=sb.height*scale}
+                    self.state.storyboard.scale = scale
+
                     local divisor = 1 -- only save every n-th thumbnail
                     if thumbnailer_options.storyboard_max_thumbnail_count then
                         divisor = math.ceil(self.state.thumbnail_count / thumbnailer_options.storyboard_max_thumbnail_count)