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media assets: save audio volume levels in media metadata.

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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
This commit is contained in:
evazion
2022-11-04 17:01:11 -05:00
parent a244ec5a3b
commit e005520ad8
5 changed files with 169 additions and 4 deletions
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53
test/unit/media_file_test.rb
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@@ -216,6 +216,33 @@ class MediaFileTest < ActiveSupport::TestCase
assert_equal("LC", file.metadata["FFmpeg:AudioProfile"])
assert_equal("stereo", file.metadata["FFmpeg:AudioLayout"])
assert_equal(128002, file.metadata["FFmpeg:AudioBitRate"])
assert_equal(0.1318, file.metadata["FFmpeg:AudioPeakLoudness"])
assert_equal(0.0193, file.metadata["FFmpeg:AudioAverageLoudness"])
assert_equal(0, file.metadata["FFmpeg:AudioLoudnessRange"])
assert_equal(0.7562, file.metadata["FFmpeg:AudioSilencePercentage"])
end
should "determine the metadata for a video with silent audio" do
file = MediaFile.open("test/files/mp4/test-silent-audio.mp4")
assert_equal(false, file.is_corrupt?)
assert_equal(5.736, file.duration)
assert_equal(1.74, file.frame_rate.round(2))
assert_equal(10, file.frame_count)
assert_equal(10, file.metadata["FFmpeg:FrameCount"])
assert_equal("isom", file.metadata["FFmpeg:MajorBrand"])
assert_equal("yuv420p", file.metadata["FFmpeg:PixFmt"])
assert_equal("h264", file.metadata["FFmpeg:VideoCodec"])
assert_equal("Constrained Baseline", file.metadata["FFmpeg:VideoProfile"])
assert_equal(25003, file.metadata["FFmpeg:VideoBitRate"])
assert_equal("aac", file.metadata["FFmpeg:AudioCodec"])
assert_equal("LC", file.metadata["FFmpeg:AudioProfile"])
assert_equal("stereo", file.metadata["FFmpeg:AudioLayout"])
assert_equal(2100, file.metadata["FFmpeg:AudioBitRate"])
assert_equal(0, file.metadata["FFmpeg:AudioPeakLoudness"])
assert_equal(0.0003, file.metadata["FFmpeg:AudioAverageLoudness"])
assert_equal(0, file.metadata["FFmpeg:AudioLoudnessRange"])
assert_equal(0.9999, file.metadata["FFmpeg:AudioSilencePercentage"])
end
should "determine the metadata for a video without audio" do
@@ -283,6 +310,30 @@ class MediaFileTest < ActiveSupport::TestCase
assert_equal("opus", file.metadata["FFmpeg:AudioCodec"])
assert_equal("stereo", file.metadata["FFmpeg:AudioLayout"])
assert_equal(50661, file.metadata["FFmpeg:AudioBitRate"])
assert_equal(0.1274, file.metadata["FFmpeg:AudioPeakLoudness"])
assert_equal(0.0186, file.metadata["FFmpeg:AudioAverageLoudness"])
assert_equal(0, file.metadata["FFmpeg:AudioLoudnessRange"])
assert_equal(0.7506, file.metadata["FFmpeg:AudioSilencePercentage"])
end
should "determine the metadata for a video with silent audio" do
file = MediaFile.open("test/files/webm/test-silent-audio.webm")
assert_equal(0.501, file.duration)
assert_equal(10/0.501, file.frame_rate) # 19.96
assert_equal(10, file.frame_count)
assert_equal(10, file.metadata["FFmpeg:FrameCount"])
assert_equal("yuv420p", file.metadata["FFmpeg:PixFmt"])
assert_equal("vp8", file.metadata["FFmpeg:VideoCodec"])
assert_equal("0", file.metadata["FFmpeg:VideoProfile"])
assert_equal(188407, file.metadata["FFmpeg:VideoBitRate"])
assert_equal("opus", file.metadata["FFmpeg:AudioCodec"])
assert_equal("stereo", file.metadata["FFmpeg:AudioLayout"])
assert_equal(1197, file.metadata["FFmpeg:AudioBitRate"])
assert_equal(0, file.metadata["FFmpeg:AudioPeakLoudness"])
assert_equal(0.0003, file.metadata["FFmpeg:AudioAverageLoudness"])
assert_equal(0, file.metadata["FFmpeg:AudioLoudnessRange"])
assert_equal(0.985, file.metadata["FFmpeg:AudioSilencePercentage"])
end
should "determine the metadata for a video without audio" do
@@ -519,7 +570,7 @@ class MediaFileTest < ActiveSupport::TestCase
assert_equal(true, @file.is_corrupt?)
assert_equal("libvips error", @file.error)
assert_equal(nil, @file.frame_count)
assert_nil(@file.frame_count)
assert_equal([575, 800], @file.dimensions)
assert_equal("File format error", @metadata["ExifTool:Error"])
assert_equal("89a", @metadata["GIF:GIFVersion"])