Audacity help - effect = amplify

Discussion in 'Audio Hardware' started by btomarra, Apr 5, 2014.

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  1. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    When I create a wav file to load or open in audacity and look at the waveform, it looks fine. Is that the way the waveform actually looks? Or do I need to select amplify?

    For example, on one waveform, when I select Effect and Amplify, the amplification is 2.0 db and the new peak amplitude is 0.0 db. Please help me understand what this means and what effect I should use to see what the waveform actually looks like (If I am making sense here).
     
  2. Leigh

    Leigh https://orf.media

    If you select amplify, you are just multiplying each sample's value by a number slightly greater than 1.0.

    What is sounds like you are referring to is Audacity's Normalize effect. With that effect, Audacity will seek through the entire file, find the peak value, and multiply every sample by a constant factor that brings that peak sample up to the maximum value allowable for digital recordings (you can choose to normalize to a smaller value if you wish).

    You don't gain anything from amplifying other than making the track louder - a recording that is recorded too quietly will not sound good normalized, as it will raise the noise floor along with the signal, and isn't using all available bits wisely. With 24 bit recordings this is much less of an issue, but with 16 it sure can be.
     
  3. psulioninks

    psulioninks Forum Resident

    Location:
    KC Chiefs Kingdom
    The top section, "Amplification (dB)" is actually the current peak amplitude of the current file you've got loaded. The bottom section, "New Peak Amplitude (dB)" is were you would enter a value to change the peak amplitude of the file you're viewing. By default, Audacity will always show a value of 0.0 in this field as that is the highest peak you'd ever want to avoid clipping.

    As an example, if the value in the top section is 1.9, and the value in the lower section is o.o, processing the file with these settings would result in a new peak amplitude of 0.0.
     
  4. psulioninks

    psulioninks Forum Resident

    Location:
    KC Chiefs Kingdom
    It depends on the version of Audacity being used. Historically, the Amplify feature is what other software manufacturers usually refer to as normalizing.

    Audacity 1.3.13 and earlier
    For all earlier versions of Audacity if you select multiple tracks, or tracks with more than one channel (stereo tracks) and apply the Normalize effect, then all audio channels within the selected tracks will be independently normalized to the same peak level. If multiple tracks contain intentional differences in peak levels, you should never normalize any of them. The only way to preserve the relative balance between them is to select them all as a group and amplify them, so they are all scaled up by the same amount.
     
  5. Leigh

    Leigh https://orf.media

    No, you can pick whatever value you want (including a negative value to quiet things down) and you can clip to your heart's content. Normalize is under the same menu as Amplify.
     
  6. psulioninks

    psulioninks Forum Resident

    Location:
    KC Chiefs Kingdom
    From their Wiki: This issue has sparked off several lively debates in our community. Audacity's Normalize effect breaks with the convention of many other audio programs. In those programs, "normalize" maximizes multiple tracks against the peak level common to all of them, so retaining their relative balance. If you've got a single file that consists of several different tracks, the Amplify feature will, indeed, do what Normalize does with other programs.

    It appears the newer version of Audacity allows for a similar process with Normalize now, but also with the ability to remove DC offset.
     
    Last edited: Apr 5, 2014
  7. Mister Charlie

    Mister Charlie "Music Is The Doctor Of My Soul " - Doobie Bros.

    Location:
    Aromas, CA USA
    If the OP is asking about *looking* at the soundwave as rendered by Audacity, perhaps they mean whether or not to zoom in until you see one very long continuous 'wave' (the "+" magnifying glass icon); or perhaps they are just wondering if what they hear is what they see (for editing purposes). The answer to that would be yes and no. What you hear is more important than what you see, however having the ability to see where you are and have random access to any spot instantly makes having the graph a vital tool. If in doubt, go with your ears.

    In Audacity Amplify is a volume control for the song, a selected slice or a note (even to individual samples). Up or down. Normalize can be set to a lower than 0.0 db (mine is -3.0) and it will simply drop the peaks to go no higher, basically turning down the loudest part of the track along with everything else) so the peak is not over your setting.

    (1.3 is the older version, the newer Audacity versions normalize each channel independently if you wish...I would definitely go with the free upgrade to the latest versions.)

    If I misunderstood, sorry, carry on.
     
    Last edited: Apr 5, 2014
  8. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR

    Thank you. Let me better explain. I wanted to use Audacity to see the waveform on how the cd was mastered: clipped peaks, or squashed waveforms. When I took a screenshot and posted it in a thread a friend and fellow forum member suggested I amplify it to see compression. I just want to see the waveform unaltered: is it mastered hot, are the peaks clipped without boosting anything (am I making sense)? So, should I just open the file in Audacity and post the screenshot here in threads without amplification?

    Let me illustrate:

    That's All Right - Elvis at Sun amplified:

    That's Alright Mama.png


    Now unamplified:

    That's All Right (non amplified).png
     
  9. Ortofun

    Ortofun Well-Known Member

    Location:
    nowhere
    If you want to see where it is clipping, go to 'view' and select 'show clipping' then it will be indicated in red.

    In your amplified one it will show some clipping possibly at a couple of positions, because it has been amplified and is not a representation of the file you opened/imported.

    I think :)
     
  10. Antares

    Antares Forum Resident

    Location:
    Flanders
    btomarra, "Amplify" is hardly relevant for your purpose here. If a recording was compressed or clipped / peak limited or whatever you want to call it at the mastering stage, those peaks are gone forever. You can't reproduce them after the fact by amplifying the sound and bringing the max. signal up to 0dB. You can only evaluate the waveform and see if the peaks look intact or whether they all look "shaved-off" to the same level and barely extend from the average sound level. This isn't really affected by looking at the original or the "amplified" waveform - the relative levels don't change. That Elvis track doen't really look like it's been heavily compressed or "brickwalled".
     
  11. Jim T

    Jim T Forum Resident

    Location:
    Mars
    Amplify and Normalize are similar, but not the same. You can amplify the track by any db setting you choose where normalize will raise the entire track to near 0 db which is used mainly for maintaining track to track loudness similarity. Remember that if you are doing any increase in EQ at particular frequencies that is raising or lowering the loudness just the same.

    If you are adjusting any EQ do it before you do any general Amplify or Normalizing of the tracks to insure you have enough headroom left ( levels below 0). Remember: Overs in digital are a bad thing so keep your levels about -1db down from "0". I can choose in my programs at what peak level do I want to normalize and generally it is at -2db to -1db to stay clear of overs.

    I don't seem to hear any quality loss in doing any of this in my Sony Sound Forge or NCH WavPad programs, but they cost money and Audacity is free and I have not used it. I try to do as little as possible to my files, even the ones I record from my Concert Recording work at our University. I try and treat my recordings like an egg in a shell...handle with care.

    In your waveforms, it is hard to see, but it looks like you might have raised your peaks to the limit and possibly more. I would be trying to leave some space at the top of your peak waveforms. But, you can hear "overs" if you have any.
     
    Last edited: Apr 6, 2014
  12. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    The show clipping box is checked. I leave it that way.
     
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  13. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    The unamplified waveform is without any effects (amplify or normalize). That is after converting to Wav from itunes and opening in Audacity. Kevan Budd mastered those Sun tracks and I don't think from a posted interview here he uses much compression. Here is his comment:

    http://www.elvisinfonet.com/interview_kevanbudd.html
     
  14. Mister Charlie

    Mister Charlie "Music Is The Doctor Of My Soul " - Doobie Bros.

    Location:
    Aromas, CA USA
    See the wave unamplified? That is your true representation. 'Amplifying it' to see compression is wrong.

    If it were over-compressed/brickwalled limited there would be few if any spikes as you move along the wave, it would all be cut off flat at the top. This looks like a perfectly good file, to amplify it would cause some clipping.
     
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  15. Jim T

    Jim T Forum Resident

    Location:
    Mars
    -----------------------
    That was exactly my point in that it is easier to adjust amp vol a few db than risk over amplifying the file. Why I normalize 1 to 2 db below "0". Look in your "Normalized" settings if there is a way for you to set that threshold -1db to -2db below peak levels.
     
  16. Mister Charlie

    Mister Charlie "Music Is The Doctor Of My Soul " - Doobie Bros.

    Location:
    Aromas, CA USA
    Yes, there is. -3.0 is usually my best normalizing.
     
  17. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    And thank you. That helps me. Now in the future, when I post waveforms I will leave them as is. And I have seen unamplified waveforms that I have saved on my PC that do show limiting:

    For example: Freedom Rider - John Barleycorn remaster (unamplified). BTW, how does this waveform look?


    Freedom Rider remaster unamplified.png
     
  18. Mister Charlie

    Mister Charlie "Music Is The Doctor Of My Soul " - Doobie Bros.

    Location:
    Aromas, CA USA
    Fine, you have all the peaks and and dynamic range well within limits.

    Looks like it was compressed some based on the middle lightened part of the soundwave but that is pure conjecture on my part.

    Here is a normalized to -3.0 tune, with as you can see all the info nicely in spec and no clipping (shaving off the tops of the high/low peaks).

    monk 1.jpg

    Now here is is overamplified/compressed/brickwalled:

    This is the same song compressed. Note it still fits in the general window, one or two possible clipping issues (the line hitting the very top @ 1.0) but still louder, beefier in that middle section I mentioned.

    comp monk.jpg
    Now this would have to be heard to know if it was too loud/compressed. You can't rely on this graph alone. Ears are the best predictor.

    Here is what you do NOT want: the tops smashed and clipped and basically gone:

    brick.jpg
    Note how the tops of most all the peaks and the bottoms of all the bottoms are off the chart, and now being totally clipped.

    If I normalize it back down now to the -3.0 db I usually listen to things at you clearly see the brickwalling effect, the shaving off of most any dynamic range and everything is a loud headache inducing mess. THIS sort of thing is what you are looking to indicate a problem file.

    The files you've posted all look like pretty solid wave files, not crapped out like the above.
     
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  19. Leigh

    Leigh https://orf.media

    If you left click on the scale that goes from -1 to 1 it will reduce the scale range without changing the music... and right clicking will increase the scale range. I find this useful when editing quiet bits to increase the amplitude of the waveform.
     
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  20. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    A general thank you to everyone who posted here (especially Leigh & Mister Charlie). I have learned more in this thread than in the last few years on the forum!
     
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  21. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    In comparing the waveforms you posted it really brings out how compression affects the waveform and what I can look for. Thank you! A really clear explanation!
     
  22. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    One last waveform and question:

    Glad unamplified.png

    Glad - John Barleycorn remaster (unamplified). This looks compressed or limited. However, if I zoom in:

    Glad zoom in.png

    Is the first waveform like that because it is a long track and it's zoomed out a bit?
     
  23. Antares

    Antares Forum Resident

    Location:
    Flanders
    Yes, that's a horizontal zoom (time scale) and even if it makes the waveform look less dense or compact, it doesn't change the relation between peak levels and average sound level (which is what compression is about). What Leigh referred to above is the vertical zoom function that lets you magnify the waveform when levels are generally low. I'm pretty sure that's why you were originally asked to use the Amplify effect, because it essentially does the same thing, magnify or zoom in on the waveform's vertical scale (amplitude).
     
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  24. Jim T

    Jim T Forum Resident

    Location:
    Mars
    --------------------------------------
    This looks like a decent amount of compression has been applied, but no limiting that I can see. limiting looks like the tops of the waveforms are perfectly flat, like you went to the barber had him give you one of those old style flat-top hair cuts. The peak levels do show some minor differences, but not much. At least to me. You probably have many cds that have been peak limited that you could pull a track off of and view in your editor.
     
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  25. btomarra

    btomarra Classic Rock Audiophile Thread Starter

    Location:
    Little Rock, AR
    Thank you for explaining what to look for if limiting was applied.
     
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