Fall back to video container for duration

Some video formats, such as WebM, do not store duration information at
the level of the video stream.  Instead, the duration is stored as part
of the container format information.

This commit modifies `VideoAnalyzer` to use the duration from the video
container when the duration from the video stream is not available.

Fixes #40130.

activestorage/lib/active_storage/analyzer/video_analyzer.rb

@@ -44,7 +44,8 @@ module ActiveStorage
       end
 
       def duration
-        Float(video_stream["duration"]) if video_stream["duration"]
+        duration = video_stream["duration"] || container["duration"]
+        Float(duration) if duration
       end
 
       def angle
@@ -98,12 +99,22 @@ module ActiveStorage
         probe["streams"] || []
       end
 
+      def container
+        probe["format"] || {}
+      end
+
       def probe
-        download_blob_to_tempfile { |file| probe_from(file) }
+        @probe ||= download_blob_to_tempfile { |file| probe_from(file) }
       end
 
       def probe_from(file)
-        IO.popen([ ffprobe_path, "-print_format", "json", "-show_streams", "-v", "error", file.path ]) do |output|
+        IO.popen([ ffprobe_path,
+          "-print_format", "json",
+          "-show_streams",
+          "-show_format",
+          "-v", "error",
+          file.path
+        ]) do |output|
           JSON.parse(output.read)
         end
       rescue Errno::ENOENT

activestorage/test/analyzer/video_analyzer_test.rb

@@ -45,9 +45,21 @@ class ActiveStorage::Analyzer::VideoAnalyzerTest < ActiveSupport::TestCase
     assert_nil metadata[:display_aspect_ratio]
   end
 
+  test "analyzing a video with a container-specified duration" do
+    blob = create_file_blob(filename: "video.webm", content_type: "video/webm")
+    metadata = extract_metadata_from(blob)
+
+    assert_equal 640, metadata[:width]
+    assert_equal 480, metadata[:height]
+    assert_equal 5.229000, metadata[:duration]
+  end
+
   test "analyzing a video without a video stream" do
     blob = create_file_blob(filename: "video_without_video_stream.mp4", content_type: "video/mp4")
     metadata = extract_metadata_from(blob)
-    assert_equal({ "analyzed" => true, "identified" => true }, metadata)
+
+    assert_not_includes metadata, :width
+    assert_not_includes metadata, :height
+    assert_equal 1.022000, metadata[:duration]
   end
 end