Support anamorphic videos

lib/philomena_media/gif_preview.ex

@@ -17,9 +17,7 @@ defmodule PhilomenaMedia.GifPreview do
   Generate a GIF preview of the given video input with evenly-spaced sample points.
 
   The input should have pre-computed duration `duration`. The `dimensions`
-  are a `{target_width, target_height}` tuple of the largest dimensions desired,
+  are a `{target_width, target_height}` tuple.
-  and the image will be resized to fit inside the box of those dimensions,
-  preserving aspect ratio.
 
   Depending on the input file, this may take a long time to process.
 
@@ -81,8 +79,7 @@ defmodule PhilomenaMedia.GifPreview do
       "#{concat_input_pads} concat=n=#{num_images}, settb=1/#{target_framerate}, setpts=N [concat]"
 
     scale_filter =
-      "[concat] scale=width=#{target_width}:height=#{target_height}:" <>
+      "[concat] scale=width=#{target_width}:height=#{target_height},setsar=1 [scale]"
-        "force_original_aspect_ratio=decrease [scale]"
 
     split_filter = "[scale] split [s0][s1]"
 

lib/philomena_media/processors/webm.ex

@@ -87,7 +87,7 @@ defmodule PhilomenaMedia.Processors.Webm do
 
     cond do
       thumb_name in [:thumb, :thumb_small, :thumb_tiny] ->
-        gif = scale_gif(file, duration, target_dimensions)
+        gif = scale_gif(file, duration, dimensions, target_dimensions)
 
         [
           {:copy, webm, "#{thumb_name}.webm"},
@@ -104,10 +104,9 @@ defmodule PhilomenaMedia.Processors.Webm do
   end
 
   defp scale_videos(file, dimensions, target_dimensions) do
-    {width, height} = box_dimensions(dimensions, target_dimensions)
+    filter = scale_filter(dimensions, target_dimensions)
     webm = Briefly.create!(extname: ".webm")
     mp4 = Briefly.create!(extname: ".mp4")
-    scale_filter = "scale=w=#{width}:h=#{height}"
 
     {_output, 0} =
       System.cmd("ffmpeg", [
@@ -131,7 +130,7 @@ defmodule PhilomenaMedia.Processors.Webm do
         "-crf",
         "31",
         "-vf",
-        scale_filter,
+        filter,
         "-threads",
         "4",
         "-max_muxing_queue_size",
@@ -152,7 +151,7 @@ defmodule PhilomenaMedia.Processors.Webm do
         "-b:v",
         "5M",
         "-vf",
-        scale_filter,
+        filter,
         "-threads",
         "4",
         "-max_muxing_queue_size",
@@ -164,9 +163,8 @@ defmodule PhilomenaMedia.Processors.Webm do
   end
 
   defp scale_mp4_only(file, dimensions, target_dimensions) do
-    {width, height} = box_dimensions(dimensions, target_dimensions)
+    filter = scale_filter(dimensions, target_dimensions)
     mp4 = Briefly.create!(extname: ".mp4")
-    scale_filter = "scale=w=#{width}:h=#{height}"
 
     {_output, 0} =
       System.cmd("ffmpeg", [
@@ -188,7 +186,7 @@ defmodule PhilomenaMedia.Processors.Webm do
         "-b:v",
         "5M",
         "-vf",
-        scale_filter,
+        filter,
         "-threads",
         "4",
         "-max_muxing_queue_size",
@@ -199,17 +197,23 @@ defmodule PhilomenaMedia.Processors.Webm do
     mp4
   end
 
-  defp scale_gif(file, duration, dimensions) do
+  defp scale_gif(file, duration, dimensions, target_dimensions) do
+    {width, height} = box_dimensions(dimensions, target_dimensions)
     gif = Briefly.create!(extname: ".gif")
 
-    GifPreview.preview(file, gif, duration, dimensions)
+    GifPreview.preview(file, gif, duration, {width, height})
 
     gif
   end
 
+  defp scale_filter(dimensions, target_dimensions) do
+    {width, height} = box_dimensions(dimensions, target_dimensions)
+    "scale=w=#{width}:h=#{height},setsar=1"
+  end
+
   # x264 requires image dimensions to be a multiple of 2
   # -2 = ~1
-  def box_dimensions({width, height}, {target_width, target_height}) do
+  defp box_dimensions({width, height}, {target_width, target_height}) do
     ratio = min(target_width / width, target_height / height)
     new_width = min(max(trunc(width * ratio) &&& -2, 2), target_width)
     new_height = min(max(trunc(height * ratio) &&& -2, 2), target_height)