Fix some media attachments being converted with too high framerates (#17619)

Video files with variable framerates are converted to constant framerate videos
and the output framerate picked by ffmpeg is based on the original file's
container framerate (which can be different from the average framerate).

This means that an input video with variable framerate with about 30 frames per
second on average, but a maximum of 120 fps will be converted to a constant 120
fps file, which won't be processed by other Mastodon servers.

This commit changes it so that input files with VFR and a maximum framerate
above the framerate threshold are converted to VFR files with the maximum frame
rate enforced.

diff --git a/app/lib/video_metadata_extractor.rb b/app/lib/video_metadata_extractor.rb
index 03e40f923e5f0f2e8c638a66634df667e5bca3ed..2896620cb21b09f275dcef8d88703ff59239ba9b 100644 (file)
--- a/app/lib/video_metadata_extractor.rb
+++ b/app/lib/video_metadata_extractor.rb
@@ -2,7 +2,7 @@
 
 class VideoMetadataExtractor
   attr_reader :duration, :bitrate, :video_codec, :audio_codec,
-              :colorspace, :width, :height, :frame_rate
+              :colorspace, :width, :height, :frame_rate, :r_frame_rate
 
   def initialize(path)
     @path     = path
@@ -42,6 +42,7 @@ class VideoMetadataExtractor
         @width       = video_stream[:width]
         @height      = video_stream[:height]
         @frame_rate  = video_stream[:avg_frame_rate] == '0/0' ? nil : Rational(video_stream[:avg_frame_rate])
+        @r_frame_rate = video_stream[:r_frame_rate] == '0/0' ? nil : Rational(video_stream[:r_frame_rate])
       end
 
       if (audio_stream = audio_streams.first)

diff --git a/app/models/media_attachment.rb b/app/models/media_attachment.rb
index 0a9d05f1d70fb4e73df617bdf70b2bc3f70eac59..a3115637e51555d2632fa0f58f542d0d67fd1d1a 100644 (file)
--- a/app/models/media_attachment.rb
+++ b/app/models/media_attachment.rb
@@ -38,6 +38,12 @@ class MediaAttachment < ApplicationRecord
 
   MAX_DESCRIPTION_LENGTH = 1_500
 
+  IMAGE_LIMIT = 10.megabytes
+  VIDEO_LIMIT = 40.megabytes
+
+  MAX_VIDEO_MATRIX_LIMIT = 2_304_000 # 1920x1200px
+  MAX_VIDEO_FRAME_RATE   = 60
+
   IMAGE_FILE_EXTENSIONS = %w(.jpg .jpeg .png .gif).freeze
   VIDEO_FILE_EXTENSIONS = %w(.webm .mp4 .m4v .mov).freeze
   AUDIO_FILE_EXTENSIONS = %w(.ogg .oga .mp3 .wav .flac .opus .aac .m4a .3gp .wma).freeze
@@ -75,6 +81,7 @@ class MediaAttachment < ApplicationRecord
   VIDEO_FORMAT = {
     format: 'mp4',
     content_type: 'video/mp4',
+    vfr_frame_rate_threshold: MAX_VIDEO_FRAME_RATE,
     convert_options: {
       output: {
         'loglevel' => 'fatal',
@@ -152,12 +159,6 @@ class MediaAttachment < ApplicationRecord
     all: '-quality 90 -strip +set modify-date +set create-date',
   }.freeze
 
-  IMAGE_LIMIT = 10.megabytes
-  VIDEO_LIMIT = 40.megabytes
-
-  MAX_VIDEO_MATRIX_LIMIT = 2_304_000 # 1920x1200px
-  MAX_VIDEO_FRAME_RATE   = 60
-
   belongs_to :account,          inverse_of: :media_attachments, optional: true
   belongs_to :status,           inverse_of: :media_attachments, optional: true
   belongs_to :scheduled_status, inverse_of: :media_attachments, optional: true

diff --git a/lib/paperclip/transcoder.rb b/lib/paperclip/transcoder.rb
index ec13050382776a96ea1bcc367926a76be56df01f..afd9f58ff695c00b39e57b1485068e097679f7a1 100644 (file)
--- a/lib/paperclip/transcoder.rb
+++ b/lib/paperclip/transcoder.rb
@@ -13,6 +13,7 @@ module Paperclip
       @time                = options[:time] || 3
       @passthrough_options = options[:passthrough_options]
       @convert_options     = options[:convert_options].dup
+      @vfr_threshold       = options[:vfr_frame_rate_threshold]
     end
 
     def make
@@ -41,6 +42,11 @@ module Paperclip
       when 'mp4'
         @output_options['acodec'] = 'aac'
         @output_options['strict'] = 'experimental'
+
+        if high_vfr?(metadata) && !eligible_to_passthrough?(metadata)
+          @output_options['vsync'] = 'vfr'
+          @output_options['r'] = @vfr_threshold
+        end
       end
 
       command_arguments, interpolations = prepare_command(destination)
@@ -88,13 +94,21 @@ module Paperclip
     end
 
     def update_options_from_metadata(metadata)
-      return unless @passthrough_options && @passthrough_options[:video_codecs].include?(metadata.video_codec) && @passthrough_options[:audio_codecs].include?(metadata.audio_codec) && @passthrough_options[:colorspaces].include?(metadata.colorspace)
+      return unless eligible_to_passthrough?(metadata)
 
       @format          = @passthrough_options[:options][:format] || @format
       @time            = @passthrough_options[:options][:time]   || @time
       @convert_options = @passthrough_options[:options][:convert_options].dup
     end
 
+    def high_vfr?(metadata)
+      @vfr_threshold && metadata.r_frame_rate && metadata.r_frame_rate > @vfr_threshold
+    end
+
+    def eligible_to_passthrough?(metadata)
+      @passthrough_options && @passthrough_options[:video_codecs].include?(metadata.video_codec) && @passthrough_options[:audio_codecs].include?(metadata.audio_codec) && @passthrough_options[:colorspaces].include?(metadata.colorspace)
+    end
+
     def update_attachment_type(metadata)
       @attachment.instance.type = MediaAttachment.types[:gifv] unless metadata.audio_codec
     end