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  1. #21
    Wow, Dave, where ya bin!

    Evan - shouldn't say "feedback" to audio people.

    It comes down to how you define "loudness." It's easy, especially with today's technology, to measure any aspect of audio to any degree of precision you want. The tough part is, and always has been, to come up with measurement methods that correspond to what we actually hear, subjectively. The original "volume unit" meter was an attempt in that direction. Neither slow averaging meters nor fast peak meters give readings that bear any resemblance to perceived loudness.

    I can only speak about radio, which is what I'm closest to. In the US at least, radio stations apply ridiculous amounts of compression to their signal at all times. It is impossible for ads to be objectively louder - but subjectively they often are. This is psychological. If you record a person talking and a person screaming and then play them back at the exact same level, the screaming person will seem louder. Ad makers are simply experts at these psychological factors.

    I think it would be possible to design an ad detector that would pick out an ad maybe 65% of the time - not much better than pure chance, 50/50. The problem is, it would be fooled and mute real programming too. If an ad detector muted 65% of ads but also knocked holes in 25% of real programming, would it be acceptable?

  2. #22
    evan - make sure it works with A/52 and surround sound encodings. Also, for DVR replay (anything not live), you can look ahead for more data.
    Eric Adler (tonsofpcs)
    http://www.videoproductionsupport.com/ Chat at: http://tinyurl.com/vpschat
    Follow me on twitter: @videosupport @eric_adler

  3. #23
    Senior Member SC358's Avatar
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    If funny how this old discussion came up again.

    As a matter of fact, I have been noticing a LOT of inconsistent levels from my cable provider three weeks ago. It appears to be differences in levels between national commercials and local commercials. I do not perceive this, I'm sure it is because if I set the local commercial to a nominal level, afterwards all other content is much lower and unintelligible. Maybe it's the local providers fault for sending out inconsistencies???
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  4. #24
    Years later and wiser, I have come to realize:

    It is not the cable providers fault (although they *could* fix it by doubling the amount of equipment in their headend facilities). It isn't exactly the broadcasters' fault either (although it is easy to blame them). It's the standard's fault! In analog, we used to have a limit of what our sound level could be; beyond that it would be unintelligible. We also had requirements that we stay near that level (and it was a good idea, since if you dropped too far away, a degraded signal would quickly remove audio) preventing commercials from being run at higher levels than program content. Now, we have digital. We still have a maximum level, but we also usually allow for headroom between our normal level and our maximum, since analog above its normal level does not hard clip, when converted to digital it would. Enter commercials, preproduced, compressed to reach the high digital levels, never even run through any device that can change levels until it hits air - at which point it is too late. We also have metadata that we set that should match our "dialog level" (which, as per spec, is the average level of our audio over a 24 hour period). Read that again. 24 hour period. As long as levels over that 24 hour period average to what i set my normal level to (which a receiver either at a head-end or a viewer's set reads and adjusts analog output audio level for), I'm allowed to tweak levels as I please. So, if 5 minutes per hour go a bit over 3dB (noticeably) higher, how much lower do the other 55 minutes of the hour need to go? (I'm not going to do this math, but its not 3dB).

    That's why. Feel free to curse the ATSC.

    Note: it's a bit more complex than that, but that's the jist of it.
    Eric Adler (tonsofpcs)
    http://www.videoproductionsupport.com/ Chat at: http://tinyurl.com/vpschat
    Follow me on twitter: @videosupport @eric_adler

  5. #25
    Senior Member SC358's Avatar
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    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  6. #26
    Administrator Dave's Avatar
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    And now this from the International Telecommunication Union...

    Geneva, 18 January 2010 A new ITU standard on audio levels for broadcast television is on the table aimed at putting an end to annoying variations in sound volume between programmes and advertising breaks.
    Full press release: http://www.itu.int/newsroom/press_releases/2010/03.html

    BTW this thread is now over 6 years old - I guess some things take a while to sort out.
    Dave Owen
    MediaCollege.com

  7. #27
    I little secret I just found on my tv: If you hit menu and then setup, you may find auto volume control. The setting said that it was on, so I turned it off. Now the problem with the blasting of volume when commercials come on is gone! YEAH! I can watch tv without the remote in hand, waiting for the next break in the program. I am liking this!

  8. #28
    It's pointless to argue about the definition of "louder." The bottom line is, can anything be done about it? And the answer is, no. Because, as Dave said: objectively, measurably, commercials are not higher in level. The perception of loudness is just that, a subjective perception. An electronic circuit cannot be designed to measure it; a legal standard cannot be established to regulate it. Rock music seems louder to someone who doesn't like rock than someone who does. A screaming person sounds louder even if the actual level is lower than normal.

    Some things ya just gotta live with. Or not...I haven't watched a TV show in five years.

  9. #29
    OOOH, this is a hot topic - several people posted while I was typing.

    In my area, and many others, there's enough audio compression on all the TV channels that an automatic volume control won't do any good. All the AVC that can be done, has been done.

    And there are a lot of things advertisers can do that have nothing to do with volume. Like sticking a random "beep" in the soundtrack that subliminally catches your attention.

  10. #30
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    thanks,this topic is helpful for me. i am researching

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