diff --git a/app/logical/ffmpeg.rb b/app/logical/ffmpeg.rb
index a89984bd8..35d0b62f0 100644
--- a/app/logical/ffmpeg.rb
+++ b/app/logical/ffmpeg.rb
@@ -46,11 +46,11 @@ class FFmpeg
   end
 
   def width
-    video_streams.first[:width]
+    video_stream[:width]
   end
 
   def height
-    video_streams.first[:height]
+    video_stream[:height]
   end
 
   # @see https://trac.ffmpeg.org/wiki/FFprobeTips#Duration
@@ -68,8 +68,8 @@ class FFmpeg
 
   # @return [Integer, nil] The number of frames in the video or animation, or nil if unknown.
   def frame_count
-    if video_streams.first&.has_key?(:nb_frames)
-      video_streams.first[:nb_frames].to_i
+    if video_stream.has_key?(:nb_frames)
+      video_stream[:nb_frames].to_i
     elsif playback_info.has_key?(:frame)
       playback_info[:frame].to_i
     else
@@ -83,6 +83,14 @@ class FFmpeg
     frame_count / duration
   end
 
+  def video_codec
+    video_stream[:codec_name]
+  end
+
+  def video_stream
+    video_streams.first || {}
+  end
+
   def video_streams
     metadata[:streams].to_a.select { |stream| stream[:codec_type] == "video" }
   end
diff --git a/app/logical/media_file.rb b/app/logical/media_file.rb
index ebb145378..9b74ef336 100644
--- a/app/logical/media_file.rb
+++ b/app/logical/media_file.rb
@@ -156,6 +156,16 @@ class MediaFile
     file_ext.in?([:webm, :mp4])
   end
 
+  # @return [Boolean] True if the file is a MP4.
+  def is_mp4?
+    file_ext == :mp4
+  end
+
+  # @return [Boolean] True if the file is a WebM.
+  def is_webm?
+    file_ext == :webm
+  end
+
   # @return [Boolean] true if the file is a Pixiv ugoira
   def is_ugoira?
     file_ext == :zip
diff --git a/app/logical/media_file/video.rb b/app/logical/media_file/video.rb
index badab7be6..ac371ced5 100644
--- a/app/logical/media_file/video.rb
+++ b/app/logical/media_file/video.rb
@@ -5,7 +5,7 @@
 #
 # @see https://github.com/streamio/streamio-ffmpeg
 class MediaFile::Video < MediaFile
-  delegate :duration, :frame_count, :frame_rate, :has_audio?, to: :video
+  delegate :duration, :frame_count, :frame_rate, :has_audio?, :video_codec, :video_stream, :video_streams, :audio_streams, to: :video
 
   def dimensions
     [video.width, video.height]
@@ -16,14 +16,12 @@ class MediaFile::Video < MediaFile
   end
 
   def is_supported?
-    case file_ext
-    when :webm
-      metadata["Matroska:DocType"] == "webm"
-    when :mp4
-      true
-    else
-      false
-    end
+    return false if video_streams.size != 1
+    return false if audio_streams.size > 1
+    return false if is_webm? && metadata["Matroska:DocType"] != "webm"
+    return false if is_mp4? && !video_codec.in?(["h264", "vp9"])
+
+    true
   end
 
   # True if decoding the video fails.
diff --git a/test/components/post_preview_component_test.rb b/test/components/post_preview_component_test.rb
index 06003769a..e80b2dfbd 100644
--- a/test/components/post_preview_component_test.rb
+++ b/test/components/post_preview_component_test.rb
@@ -31,7 +31,7 @@ class PostPreviewComponentTest < ViewComponent::TestCase
 
     context "for a video post with sound" do
       should "render" do
-        @post = create(:post_with_file, tag_string: "sound", filename: "test-audio.mp4").reload
+        @post = create(:post_with_file, tag_string: "sound", filename: "mp4/test-audio.mp4").reload
         node = render_preview(@post, current_user: User.anonymous)
 
         assert_equal(post_path(@post), node.css("article a").attr("href").value)
diff --git a/test/files/mp4/test-300x300.h265.mp4 b/test/files/mp4/test-300x300.h265.mp4
new file mode 100644
index 000000000..c8df94aa8
Binary files /dev/null and b/test/files/mp4/test-300x300.h265.mp4 differ
diff --git a/test/files/test-300x300.mp4 b/test/files/mp4/test-300x300.mp4
similarity index 100%
rename from test/files/test-300x300.mp4
rename to test/files/mp4/test-300x300.mp4
diff --git a/test/files/test-audio.m4v b/test/files/mp4/test-audio.m4v
similarity index 100%
rename from test/files/test-audio.m4v
rename to test/files/mp4/test-audio.m4v
diff --git a/test/files/test-audio.mp4 b/test/files/mp4/test-audio.mp4
similarity index 100%
rename from test/files/test-audio.mp4
rename to test/files/mp4/test-audio.mp4
diff --git a/test/files/test-iso5.mp4 b/test/files/mp4/test-iso5.mp4
similarity index 100%
rename from test/files/test-iso5.mp4
rename to test/files/mp4/test-iso5.mp4
diff --git a/test/functional/uploads_controller_test.rb b/test/functional/uploads_controller_test.rb
index 82aa5efd5..7babf6f11 100644
--- a/test/functional/uploads_controller_test.rb
+++ b/test/functional/uploads_controller_test.rb
@@ -241,6 +241,16 @@ class UploadsControllerTest < ActionDispatch::IntegrationTest
           create_upload!("test/files/webm/test-512x512.mkv", user: @user)
           assert_match("File type is not supported", Upload.last.error)
         end
+
+        should "fail for a .mp4 file encoded with h265" do
+          create_upload!("test/files/mp4/test-300x300.h265.mp4", user: @user)
+          assert_match("File type is not supported", Upload.last.error)
+        end
+
+        should "fail for a .mp4 file encoded with av1" do
+          create_upload!("test/files/mp4/test-300x300.av1.mp4", user: @user)
+          assert_match("File type is not supported", Upload.last.error)
+        end
       end
 
       context "for a video longer than the video length limit" do
@@ -334,10 +344,11 @@ class UploadsControllerTest < ActionDispatch::IntegrationTest
         should_upload_successfully("test/files/test.png")
         should_upload_successfully("test/files/test-static-32x32.gif")
         should_upload_successfully("test/files/test-animated-86x52.gif")
-        should_upload_successfully("test/files/test-300x300.mp4")
-        should_upload_successfully("test/files/test-audio.mp4")
+        should_upload_successfully("test/files/mp4/test-300x300.mp4")
+        should_upload_successfully("test/files/mp4/test-300x300.vp9.mp4")
+        should_upload_successfully("test/files/mp4/test-audio.mp4")
+        should_upload_successfully("test/files/mp4/test-audio.m4v")
         should_upload_successfully("test/files/webm/test-512x512.webm")
-        should_upload_successfully("test/files/test-audio.m4v")
         # should_upload_successfully("test/files/compressed.swf")
 
         should_upload_successfully("test/files/avif/fox.profile0.8bpc.yuv420.monochrome.avif")
diff --git a/test/unit/media_file_test.rb b/test/unit/media_file_test.rb
index 2e2e2c604..0e316409c 100644
--- a/test/unit/media_file_test.rb
+++ b/test/unit/media_file_test.rb
@@ -36,7 +36,7 @@ class MediaFileTest < ActiveSupport::TestCase
 
     should "determine the correct dimensions for a mp4 file" do
       skip unless MediaFile.videos_enabled?
-      assert_equal([300, 300], MediaFile.open("test/files/test-300x300.mp4").dimensions)
+      assert_equal([300, 300], MediaFile.open("test/files/mp4/test-300x300.mp4").dimensions)
     end
 
     should "determine the correct dimensions for a ugoira file" do
@@ -110,15 +110,15 @@ class MediaFileTest < ActiveSupport::TestCase
     end
 
     should "determine the correct extension for a mp4 file" do
-      assert_equal(:mp4, MediaFile.open("test/files/test-300x300.mp4").file_ext)
+      assert_equal(:mp4, MediaFile.open("test/files/mp4/test-300x300.mp4").file_ext)
     end
 
     should "determine the correct extension for a m4v file" do
-      assert_equal(:mp4, MediaFile.open("test/files/test-audio.m4v").file_ext)
+      assert_equal(:mp4, MediaFile.open("test/files/mp4/test-audio.m4v").file_ext)
     end
 
     should "determine the correct extension for an iso5 mp4 file" do
-      assert_equal(:mp4, MediaFile.open("test/files/test-iso5.mp4").file_ext)
+      assert_equal(:mp4, MediaFile.open("test/files/mp4/test-iso5.mp4").file_ext)
     end
 
     should "determine the correct extension for a ugoira file" do
@@ -162,7 +162,7 @@ class MediaFileTest < ActiveSupport::TestCase
     should "generate a preview image for a video" do
       skip unless MediaFile.videos_enabled?
       assert_equal([150, 150], MediaFile.open("test/files/webm/test-512x512.webm").preview(150, 150).dimensions)
-      assert_equal([150, 150], MediaFile.open("test/files/test-300x300.mp4").preview(150, 150).dimensions)
+      assert_equal([150, 150], MediaFile.open("test/files/mp4/test-300x300.mp4").preview(150, 150).dimensions)
     end
 
     should "be able to fit to width only" do
@@ -196,18 +196,18 @@ class MediaFileTest < ActiveSupport::TestCase
 
   context "for an mp4 file " do
     should "detect videos with audio" do
-      assert_equal(true, MediaFile.open("test/files/test-audio.mp4").has_audio?)
-      assert_equal(false, MediaFile.open("test/files/test-300x300.mp4").has_audio?)
+      assert_equal(true, MediaFile.open("test/files/mp4/test-audio.mp4").has_audio?)
+      assert_equal(false, MediaFile.open("test/files/mp4/test-300x300.mp4").has_audio?)
     end
 
     should "determine the duration of the video" do
-      file = MediaFile.open("test/files/test-audio.mp4")
+      file = MediaFile.open("test/files/mp4/test-audio.mp4")
       assert_equal(false, file.is_corrupt?)
       assert_equal(1.002667, file.duration)
       assert_equal(10/1.002667, file.frame_rate)
       assert_equal(10, file.frame_count)
 
-      file = MediaFile.open("test/files/test-300x300.mp4")
+      file = MediaFile.open("test/files/mp4/test-300x300.mp4")
       assert_equal(false, file.is_corrupt?)
       assert_equal(5.7, file.duration)
       assert_equal(1.75, file.frame_rate.round(2))
@@ -215,9 +215,15 @@ class MediaFileTest < ActiveSupport::TestCase
     end
 
     should "detect corrupt videos" do
-      file = MediaFile.open("test/files/mp4/test-corrupt.mp4")
+      assert_equal(true, MediaFile.open("test/files/mp4/test-corrupt.mp4").is_corrupt?)
+    end
 
-      assert_equal(true, file.is_corrupt?)
+    should "detect supported files" do
+      assert_equal(true, MediaFile.open("test/files/mp4/test-300x300.mp4").is_supported?)
+      assert_equal(true, MediaFile.open("test/files/mp4/test-300x300.vp9.mp4").is_supported?)
+
+      assert_equal(false, MediaFile.open("test/files/mp4/test-300x300.h265.mp4").is_supported?)
+      assert_equal(false, MediaFile.open("test/files/mp4/test-300x300.av1.mp4").is_supported?)
     end
   end