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For videos with sound, save information about audio volume levels in the media asset's metadata. These values are stored: * FFmpeg:AudioPeakLoudness The peak loudness of the audio track, from 0.0 (silent) to 1.0 (max volume) * FFmpeg:AudioAverageLoudness The average loudness of the audio track, from 0.0 (silent) to 1.0 (max volume). * FFmpeg:AudioLoudnessRange The difference between the quietest and loudest sounds in the audio track (in decibels). * FFmpeg:AudioSilencePercentage The percentage of the video that is silent (1.0 is completely silent, 0.5 is 50% silence, 0.0 is no silence). These values are calculated based on the EBU R 128 standard, using the ffmpeg command below: ffmpeg -i file.mp4 -af silencedetect=duration=0.05:noise=0.0001,ebur128=metadata=1:peak=true:dualmono=true -f null /dev/null See the links below for details: * https://en.wikipedia.org/wiki/EBU_R_128 * https://www.ffmpeg.org/ffmpeg-filters.html#ebur128-1 * https://tech.ebu.ch/loudness * https://tech.ebu.ch/docs/tech/tech3341.pdf
73 lines
2.7 KiB
Ruby
73 lines
2.7 KiB
Ruby
# frozen_string_literal: true
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# A MediaFile for a webm or mp4 video. Uses ffmpeg to generate preview
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# thumbnails.
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#
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# @see https://github.com/streamio/streamio-ffmpeg
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class MediaFile::Video < MediaFile
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delegate :duration, :frame_count, :frame_rate, :has_audio?, :is_corrupt?, :major_brand, :pix_fmt,
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:video_codec, :video_bit_rate, :video_stream, :video_streams, :audio_codec, :audio_bit_rate,
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:audio_stream, :audio_streams, :silence_duration, :silence_percentage, :average_loudness,
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:peak_loudness, :loudness_range, :error, to: :video
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def dimensions
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[video.width, video.height]
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end
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def preview!(max_width, max_height, **options)
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preview_frame.preview!(max_width, max_height, **options)
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end
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def metadata
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super.merge({
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"FFmpeg:Error" => error,
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"FFmpeg:MajorBrand" => major_brand,
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"FFmpeg:PixFmt" => pix_fmt,
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"FFmpeg:FrameCount" => frame_count,
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"FFmpeg:VideoCodec" => video_codec,
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"FFmpeg:VideoProfile" => video_stream[:profile],
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"FFmpeg:VideoBitRate" => video_bit_rate,
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"FFmpeg:AudioCodec" => audio_codec,
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"FFmpeg:AudioProfile" => audio_stream[:profile],
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"FFmpeg:AudioLayout" => audio_stream[:channel_layout],
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"FFmpeg:AudioBitRate" => audio_bit_rate,
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"FFmpeg:AudioPeakLoudness" => peak_loudness,
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"FFmpeg:AudioAverageLoudness" => average_loudness,
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"FFmpeg:AudioLoudnessRange" => loudness_range,
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"FFmpeg:AudioSilencePercentage" => silence_percentage,
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}.compact_blank)
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end
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def is_supported?
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return false if video_streams.size != 1
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return false if audio_streams.size > 1
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return false if is_webm? && exif_metadata["Matroska:DocType"] != "webm"
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return false if is_mp4? && !video_codec.in?(["h264", "vp9"])
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# Only allow pixel formats supported by most browsers. Don't allow 10-bit video or 4:4:4 subsampling (neither are supported by Firefox).
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#
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# yuv420p: 8-bit YUV, 4:2:0 subsampling. The vast majority of videos use this format.
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# yuvj420p: 8-bit YUV, 4:2:0 subsampling, color range restricted to 16-235. Uncommon, but widely supported.
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# yuv444p: 8-bit YUV, 4:4:4 subsampling (i.e. no subsampling). Uncommon, not supported by Firefox.
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# yuv420p10le: 10-bit YUV, 4:2:0 subsampling (i.e. 10-bit video). Uncommon, not supported by Firefox.
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# gbrp: 8-bit RGB (used by VP9). Uncommon, but widely supported.
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#
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# https://github.com/FFmpeg/FFmpeg/blob/master/libavutil/pixfmt.h
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return false if !pix_fmt.in?(%w[yuv420p yuvj420p gbrp])
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true
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end
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private
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def video
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FFmpeg.new(self)
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end
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def preview_frame
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video.smart_video_preview
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end
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memoize :video, :preview_frame, :dimensions, :metadata, :duration, :has_audio?
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end
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