First Reaper master ever: mp3 export clipping

Discussion in 'Recording Studio' started by Rizzo, May 10, 2017.

  1. Rizzo

    Rizzo SS.org Regular

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    Hey guys, finally closing my first full home recording production ever, basically a whole big pilot test. I'll probably let you hear the final product, it's a cover.

    On to the meat: I made a quick essential mastering phase (eq, comp, multicomp, limiter). All ok up to limiting.
    I had a -1db ceiling just for safety, threshold was about -8.9. The track is very dynamic (minimal vocal and guitar ballad, plus backing vocals). GR never went more than 2.5/3db on the loudest peaks. So up to there, I thought I was safe.

    Then I exported mp3, 320 CBR, and the export slightly brickwalled the loudest peaks resulting in sensible clipping. Note I still dind't try a wav export.
    Re-importing the track back in reaper, I noticed dbfs peaks are logically at max -1db, but the RMS fader goes positive, up to +6 in the clipping parts, and also slightly less in other slightly less loud sections when the clipping isn't perceivable but it seems like it still did happen.

    So I'm asking myself, open-ended questions here:
    1. what's happening and where am I wrong?
    2. was it just the mp3's own compression to frak up my headroom, so should I set an even lower ceiling while rendering to mp3?
    3. or did I squash the threshold too much on the -1 ceiling? so in that case, should I lower the ceiling, or set the threshold higher, or both, or what?
    4. if nothing will clip while exporting to wav on the same settings, does it mean it's all the mp3's fault?

    Up to you, any advice is welcome. Thanks :bowdown:
     
  2. Crescendo

    Crescendo Surgical

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    1dB is enough headroom for anything really. It's your mp3 exporting that causes that. Or you're using a bad limiter plugin. I master at -0.6dBFS and get "normal" mp3 peaking. But I never export an mp3, I open the wav in a separate audio editor, edit it if I have to, and save down to mp3 then. Try VBR instead of CBR?
     
  3. Rizzo

    Rizzo SS.org Regular

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    Problem solved I guess, I was squeezing the threshold too much.
     
  4. KingAenarion

    KingAenarion Resident Studio Nerd

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    Just as a further note. From a purely theoretical perspective, if your mastering Limiter is good enough, the only value you ever really want to set it to is -0.3dBFS.

    Why that value you ask?

    Well...

    0.3dB is the smallest increment it's possible for a human ear to perceive a difference in (and even then, most can't).

    It's a value lower than 0dBFS, which means cheap nasty D/A chips in cheap CD players and the like won't hit 0dB and sound horrendous.

    So... tada.
     
  5. Crescendo

    Crescendo Surgical

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    That's until you want to publish your work via streaming services, YouTube or iTunes, because of the encoding. In that case you may want to set it between -0.3 and -1dBFS. Apple recommends 1dB of headroom.
     
  6. Rizzo

    Rizzo SS.org Regular

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    Yup, I'd want to make a video for YT.
    As for the video, is it more convenient to make it with an mp3 file or with the original wav?
     
  7. Crescendo

    Crescendo Surgical

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    When you're editing the video you wouldn't want to use compressed audio. It's just going to get compressed again when you render the video down (to mp4, hopefully). And then again when YouTube processes it.
     

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