Peak audio levels for PAL DVD?

Discussion in 'Video Cameras' started by BlahDiBlah, Nov 6, 2006.

  1. BlahDiBlah

    BlahDiBlah Guest

    Hi folks,

    does anyone know what the maximum permissable audio level is for PAL DVD?
    When preparing CDs, I usually set my limiter at -0.2dB. However, this seems
    to be waaaaay loud for DVD...

    thanks,
    Gareth
     
    BlahDiBlah, Nov 6, 2006
    #1
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  2. BlahDiBlah

    John Russell Guest

    Are you using Dolby Digital? If your not then you will notice a difference
    compared to commercial DVD's which do. This is becuase Dolby encoding
    reduces the volume used.
     
    John Russell, Nov 6, 2006
    #2
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  3. Hi Gareth,

    There is an interesting article about this at
    http://www.kenstone.net/fcp_homepage/dv_audio_peaks.html.

    I personally set my max level at -6 dB. This gives me a volume comparable
    with a standard TV broadcast and leaves enough headroom if I need to use
    really loud sound effects, like gun shots, planes taking off, etc.
    Naturally, the maximum permissable audio level for PAL DVD is 0 dB; beyond
    that clipping sets in which sounds awful.
     
    Lou van Wijhe, Nov 6, 2006
    #3
  4. BlahDiBlah

    BlahDiBlah Guest

    Hi John,

    no, just plain old stereo... hmmm maybe I need to look at encoding Dolby
    Digital? Does that make sense if I'm not working in surround?

    thanks,
    Gareth
     
    BlahDiBlah, Nov 7, 2006
    #4
  5. BlahDiBlah

    BlahDiBlah Guest

    Thanks Lou,

    I'll give -6dB a go, then.
    Interesting to see that peaks as low as -20dB were being talked about!

    Gareth
     
    BlahDiBlah, Nov 7, 2006
    #5
  6. BlahDiBlah

    John Russell Guest

    The combined bitrate for DVd Video and Audio cannot exceed 10684 BPS(or
    something like that!). If you use PCM then that takes up 1500 BPS, leaving
    the rest for video. If you use Dolby Digital 2.0 (i.e stereo) you can reduce
    the 1500 to say 256, and have either better quality video, or longer
    recordings.
     
    John Russell, Nov 7, 2006
    #6
  7. I do indeed have some commercial DVDs with max levels that low and on my
    setup I then have to turn the volume all the way up. Certainly not my
    choice.

    Lou
     
    Lou van Wijhe, Nov 7, 2006
    #7
  8. BlahDiBlah

    John Russell Guest

    P.S. The DVD- video standard requires a minimum of either a PCM or an AC3
    audio track. The AC3 track dosn't need to be 5.1, 2.0 will suffice.
     
    John Russell, Nov 7, 2006
    #8
  9. BlahDiBlah

    BlahDiBlah Guest

    Hmmm, audio compression (in terms of bitrate) is something that's passed me
    by so far. Probably due to the lack of any options besides "Uncompressed" in
    the PPro dropdown window!
    Sounds like it's something I should be doing. Thanks for the tip, John!

    Gareth
     
    BlahDiBlah, Nov 9, 2006
    #9
  10. BlahDiBlah

    Tony Morgan Guest

    In message <4550ee02$>, John Russell

    Snipped...
    I've been following this thread with some interest - but I'm puzzled.
    Does bitrate equate with peak audio level(s) ?

    IIRC dB in this context is referenced to 1Vpk-pk. And since we're
    talking volts, then -6dB is 0.5Vpk-pk.

    IIRC the trick with audio is to ensure that no peak clipping occurs - no
    matter how high the bitrate is, if clipping occurs then distortion will
    be introduced.

    To avoid audio clipping, I have (for some time) used Magix Cleaning Lab.
    Applying Normalisation seems to do the trick. I've also found useful
    (where video is shot in low audio situations) the Denoiser and Dehisser
    facilites.
     
    Tony Morgan, Nov 9, 2006
    #10
  11. Where do you use it?
    If you've got a signal with "flat-top" waveforms due to clipping at
    any previous stage, normalisation can't rescue it. You'll still get a
    nasty distorted sound, just quieter.

    There ARE tools in the more advanced audio editing programs which
    attempt to reconstruct a clipped waveform, with varying degrees of
    success.
     
    Laurence Payne, Nov 9, 2006
    #11
  12. BlahDiBlah

    G Hardy Guest

    No, they are unrelated. I think John was referring to bitrates because of
    the huge difference between PCM and AC3 bitrates, and the fact that you can
    adjust the AC3 peak during encoding from a bare PCM WAV file.

    @ john - there's a good deal of confusion regarding maximum bitrates. I've
    always thought that the maximum combined bitrate (audio+video+subpicture) is
    10.08mbps, but that can only be managed in "bursts", with no reference to
    what a "burst" actually is. The maximum sustainable combined bitrate is
    9.8mbps. For simplicity, most people max out at 9.8mbps

    However, when I went to Jim Taylor's FAQ for a reference to backup that
    assertion, it appears "Maximum video bit rate is 9.8 Mbps." and "...the
    maximum rate of combined elementary streams (audio + video + subpicture) is
    10.08.".
    http://www.dvddemystified.com/dvdfaq.html#3.4

    It's all a bit of a moot point anyway - if you encode media for DVDR that
    comes anywhere close to those levels, you'll end up with a disc that's
    pretty much unusable in most DVD players.
     
    G Hardy, Nov 9, 2006
    #12
  13. BlahDiBlah

    Tony Morgan Guest

    From my camcorder. The camcorder's AVC seems to prevent any clipping - I
    assume because it's a fast-attack/slow-decay AVC circuit [1]
    See above.
    [1] This seems to be the case, because when doing any serious "set-up"
    video work I use a MiniDisk recorder for sounds and use a clicker to
    allow me to sync the MiniDisk sound with the camcorder's sound layer
    (subsequently replacing the camcorder's sound with that from the
    MiniDisk). On the camcorder's audio (though I eventually replace it),
    you can hear the click at full volume, but the camcorder's audio level
    immediately falls, taking about three seconds to slowly come up again.
    The clicker, BTW, costs about 99p at doggie shops (used for training
    fido).
     
    Tony Morgan, Nov 9, 2006
    #13
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