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Anecdotally I've noticed that higher quality videos, whether be a 1080p HD video on the TV or a BluRay rip on a computer, the volume seems to be lower than a standard quality video. I've noticed this since at 100% volume of several really high quality video's its still difficult to hear while 100% volume of lower quality videos is deafeningly loud.

Why is this? Is there a technical reason? Is it assumed that high quality videos will be played on high quality speakers which go louder?

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2 Answers 2

up vote 9 down vote accepted

The quick answer is the Loudness War.

The longer answer is that you can increase the perceived loudness of a track by applying lots of audio compression (not to be confused with data compression on the audio file). Compression evens out the loud and soft sounds, and then you typically normalize the track so that the largest peaks are just short of clipping. The end result is very loud, but you have thrown away all the dynamics in the original material.

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Wow, I never thought that compression would do that. Thanks for the answer. –  TheLQ Oct 27 '11 at 23:27
    
I'm not sure how overcompression of audio is correlated to quality of video? The loudness war is a well-known problem in audio but I would imagine that high-quality (more likely professionally produced) videos would be compressing even more, to compete. –  Warrior Bob Oct 28 '11 at 22:17
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I guess the answer hinges on the subjectivity of "higher quality" videos. The videos that I think of as higher quality are produced with more awareness of the importance of the dynamics of sound and carefully produce a mix. A lazy or inexperienced producer will just jam a compressor on the final mixdown and crank it up. Sounds bad but loud. The more experienced producer will use compression on individual tracks where it is needed, and automate volume levels so that dynamics are retained. But if "higher quality video" simply means higher resolution (HD) video, then you are right. –  ObscureRobot Oct 28 '11 at 22:31
    
@WarriorBob this is (alas!) quite true for many audio productions, since there loudness is sort of a means of competition, for instance on the radio. But that is less of a concern for video, so the producers feel less forced to apply overly strong compression just to make the result loud. Only in cheap productions they may feel the need to compensate overall quality with brute loudness, or overuse compression for another reason: it frees you from the need to carefully adjust the levels of different signal sources. –  leftaroundabout Nov 1 '11 at 14:48
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You don't mention the specific media or format by which the video is delivered. HD video may contain surround sound encoded audio, and you might not be hearing all the channels, dpending upon your speaker setup.

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Surround wasn't an issue. On a TV with a large 5.1 setup I noticed this as well –  TheLQ Oct 27 '11 at 23:25
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This is worth pointing out - a significant amount of sound is routed through the center channel, and if you happen to be using a tiny center speaker, have it turned down, or no center at all, you will experience lower quality audio compared with a pure stereo mix. –  ObscureRobot Oct 28 '11 at 22:34
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