media assets: fix .webm files not including video/audio bit rates in metadata.

Fix .webm files not including the `FFmpeg:VideoBitRate` and `FFmpeg:AudioBitRate`
fields in the media_metadata table. This was because the .webm format
doesn't include the video or audio bit rates in the metadata, and
ffprobe doesn't calculate them either, so we have to calculate them
ourselves by hand.

Fixup for 523d7afdd.

app/logical/ffmpeg.rb

@@ -11,9 +11,10 @@ class FFmpeg
   attr_reader :file
 
   # Operate on a file with FFmpeg.
-  # @param file [File, String] a webm, mp4, gif, or apng file
+  #
+  # @param file [MediaFile, String] A webm, mp4, gif, or apng file.
   def initialize(file)
-    @file = file.is_a?(String) ? File.open(file) : file
+    @file = file.is_a?(String) ? MediaFile.open(file) : file
   end
 
   # Generate a .png preview image for a video or animation. Generates
@@ -38,7 +39,7 @@ class FFmpeg
   #
   # @return [Hash] A hash of the file's metadata. Will be empty if reading the file failed for any reason.
   def metadata
-    output = shell!("ffprobe -v quiet -print_format json -show_format -show_streams #{file.path.shellescape}")
+    output = shell!("ffprobe -v quiet -print_format json -show_format -show_streams -show_packets #{file.path.shellescape}")
     json = JSON.parse(output)
     json.with_indifferent_access
   rescue Error => e
@@ -95,6 +96,18 @@ class FFmpeg
     video_stream[:codec_name]
   end
 
+  # @return [Integer, nil] The bit rate of the video stream, in bits per second, or nil if it can't be calculated.
+  def video_bit_rate
+    if video_stream.has_key?(:bit_rate)
+      video_stream[:bit_rate].to_i
+    # .webm doesn't have the bit rate in the metadata, so we have to calculate it from the video stream size and duration.
+    elsif video_size > 0 && duration > 0
+      ((8.0 * video_size) / duration).to_i
+    else
+      nil
+    end
+  end
+
   def video_stream
     video_streams.first || {}
   end
@@ -107,6 +120,18 @@ class FFmpeg
     audio_stream[:codec_name]
   end
 
+  # @return [Integer, nil] The bit rate of the audio stream, in bits per second, or nil if it can't be calculated.
+  def audio_bit_rate
+    if audio_stream.has_key?(:bit_rate)
+      audio_stream[:bit_rate].to_i
+    # .webm doesn't have the bit rate in the metadata, so we have to calculate it from the audio stream size and duration.
+    elsif audio_size > 0 && duration > 0
+      ((8.0 * audio_size) / duration).to_i
+    else
+      nil
+    end
+  end
+
   def audio_stream
     audio_streams.first || {}
   end
@@ -119,6 +144,28 @@ class FFmpeg
     audio_streams.present?
   end
 
+  def packets
+    metadata[:packets].to_a
+  end
+
+  def video_packets
+    packets.select { |stream| stream[:codec_type] == "video" }
+  end
+
+  def audio_packets
+    packets.select { |stream| stream[:codec_type] == "audio" }
+  end
+
+  # @return [Integer] The size of the compressed video stream in bytes.
+  def video_size
+    video_packets.pluck("size").map(&:to_i).sum
+  end
+
+  # @return [Integer] The size of the compressed audio stream in bytes.
+  def audio_size
+    audio_packets.pluck("size").map(&:to_i).sum
+  end
+
   # @return [Boolean] True if the video is unplayable.
   def is_corrupt?
     error.present?
@@ -129,15 +176,25 @@ class FFmpeg
     metadata[:error] || playback_info[:error]
   end
 
-  # Decode the full video and return a hash containing the frame count, fps, and runtime.
+  # Decode the full video and return a hash containing the frame count, fps, runtime, and the sizes of the decompressed video and audio streams.
   def playback_info
-    output = shell!("ffmpeg -i #{file.path.shellescape} -f null /dev/null")
-    status_line = output.lines.grep(/\Aframe=/).first.chomp
+    # XXX `-c copy` is faster, but it doesn't decompress the stream so it can't detect corrupt videos.
+    output = shell!("ffmpeg -hide_banner -i #{file.path.shellescape} -f null /dev/null")
 
-    # status_line = "frame=   10 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.48 bitrate=N/A speed= 179x"
-    # info = {"frame"=>"10", "fps"=>"0.0", "q"=>"-0.0", "Lsize"=>"N/A", "time"=>"00:00:00.48", "bitrate"=>"N/A", "speed"=>"188x"}
-    info = status_line.scan(/\S+=\s*\S+/).map { |pair| pair.split(/=\s*/) }.to_h
-    info.with_indifferent_access
+    # time_line = "frame=   10 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.48 bitrate=N/A speed= 179x"
+    # time_info = { "frame"=>"10", "fps"=>"0.0", "q"=>"-0.0", "Lsize"=>"N/A", "time"=>"00:00:00.48", "bitrate"=>"N/A", "speed"=>"188x" }
+    time_line = output.lines.grep(/\Aframe=/).first.chomp
+    time_info = time_line.scan(/\S+=\s*\S+/).map { |pair| pair.split(/=\s*/) }.to_h
+
+    # size_line = "video:36kBkB audio:16kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown"
+    # size_info = { "video" => 36000, "audio" => 16000, "subtitle" => 0, "other streams" => 0, "global headers" => 0, "muxing overhead" => 0 }
+    size_line = output.lines.grep(/\Avideo:/).first.chomp
+    size_info = size_line.scan(/[a-z ]+: *[a-z0-9]+/i).map do |pair|
+      key, value = pair.split(/: */)
+      [key.strip, value.to_i * 1000] # [" audio", "16kB"] => ["audio", 16000]
+    end.to_h
+
+    { **time_info, **size_info }.with_indifferent_access
   rescue Error => e
     { error: e.message.strip }.with_indifferent_access
   end
@@ -149,5 +206,5 @@ class FFmpeg
     output
   end
 
-  memoize :metadata, :playback_info, :frame_count, :duration, :error
+  memoize :metadata, :playback_info, :frame_count, :duration, :error, :video_size, :audio_size
 end

app/logical/media_file/image.rb

@@ -132,7 +132,7 @@ class MediaFile::Image < MediaFile
 
   def preview_frame
     if is_animated?
-      FFmpeg.new(file).smart_video_preview
+      FFmpeg.new(self).smart_video_preview
     else
       self
     end
@@ -172,7 +172,7 @@ class MediaFile::Image < MediaFile
   end
 
   def video
-    FFmpeg.new(file)
+    FFmpeg.new(self)
   end
 
   memoize :image, :video, :preview_frame, :dimensions, :error, :metadata, :is_corrupt?, :is_animated_gif?, :is_animated_png?

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?, :is_corrupt?, :major_brand, :pix_fmt, :video_codec, :video_stream, :video_streams, :audio_codec, :audio_stream, :audio_streams, :error, to: :video
+  delegate :duration, :frame_count, :frame_rate, :has_audio?, :is_corrupt?, :major_brand, :pix_fmt, :video_codec, :video_bit_rate, :video_stream, :video_streams, :audio_codec, :audio_bit_rate, :audio_stream, :audio_streams, :error, to: :video
 
   def dimensions
     [video.width, video.height]
@@ -23,10 +23,11 @@ class MediaFile::Video < MediaFile
       "FFmpeg:FrameCount" => frame_count,
       "FFmpeg:VideoCodec" => video_codec,
       "FFmpeg:VideoProfile" => video_stream[:profile],
+      "FFmpeg:VideoBitRate" => video_bit_rate,
       "FFmpeg:AudioCodec" => audio_codec,
       "FFmpeg:AudioProfile" => audio_stream[:profile],
       "FFmpeg:AudioLayout" => audio_stream[:channel_layout],
-      "FFmpeg:AudioBitRate" => audio_stream[:bit_rate],
+      "FFmpeg:AudioBitRate" => audio_bit_rate,
     }.compact_blank)
   end
 
@@ -53,7 +54,7 @@ class MediaFile::Video < MediaFile
   private
 
   def video
-    FFmpeg.new(file)
+    FFmpeg.new(self)
   end
 
   def preview_frame