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How to make a loop that contains the last sample?

Category: Help
  • PG 9 1
    The number won't increase to the last sample, so how to make a loop that contains the last sample?
  • BO 283 13
    Message from bottrop on
    paste a little silence, noise or whatever at the end of the waveform.
    regards bottrop
  • PG 9 1
    That's nothing but a workaround. I'm seriously looking for an actual solution to this problem (bugfix needed?).
  • ZI 190 0
    SoundFont 2.01 Technical Specification - Page 26
    SoundFont 2.04 Technical Specification - Page 21

    6.3 Sample Data Looping Rules
    ....

    "In actuality, because of the various interpolation algorithms used by wavetable synthesizers, the data surrounding both the loop start and end points may affect the sound of the loop. Hence both the loop start and end points must be surrounded by continuous audio data. For example, even if the sound is programmed to continue to loop throughout the decay, sample data points must be provided beyond the loop end point. This data will typically be identical to the data at the start of the loop. A minimum of eight valid data points are required to be present before the loop start and after the loop end.

    The eight data points (four on each side) surrounding the two equivalent loop points should also be forced to be identical. By forcing the data to be identical, all interpolation algorithms are guaranteed to properly reproduce an artifact-free loop."
  • PG 9 1
    I never heard of such a requirement. The data before and after should be always well known as a sound with a loop initiated by the start and end commands always becomes a 1-dimensional wave (prefixed and suffixed by infinite silence) that can easily be interpolated. I don't get it.
  • BO 283 13
    Message from bottrop on
    well, the fact you never heard of it, does not mean it is not true. like our friend Zya wrote, there has to be a margin before and after the loop-points, so pasting a little silence at the end is not a workaround, it is the only way.
    regards bottrop
  • PG 9 1
    Who made this kind of restriction? WHO DID IT?
  • ZI 190 0
    EMU inc. Creator of soundfond format.

    Please download read the specification. http://freepats.zenvoid.org/sf2/sfspec24.pdf 
    see Page 20 (last paragraph) -21 (continued)

    6.3 Sample Data Looping Rules

    SoundFont 2.04 Technical Specification - Page 21
    SoundFont 2.01 Technical Specification - Page 26
  • I added two pictures for a better understanding.


    The first picture is where Loop starts, the second is where it ends.


    You can see that the inside and outside areas must match (complements) at both points.
  • PG 9 1
    The outer points shouldn't be necessary if the algorithm for previous or next sample handles loops correctly:

    https://i.imgur.com/zv9XUny.png 

    All points are perfectly defined. The "data surrounding both the loop start and end points" doesn't affect the sound of the loop because the algorithm is working correctly.

    And apparently even Polyphone itself breaks "the soundfont standard", if you say 4 points are required on each side but Polyphone requires 0 to the left and 1 to the right...

    This is actually problematic. When a sample is added from external software whose loop covers the entire sound, Polyphone alters it making it unusable.
  • ZI 190 0
    You haven't even read the specification, have you?
  • BO 283 13
    Message from bottrop on
    "This is actually problematic. When a sample is added from external software whose loop covers the entire sound,"
    which external software?
  • 70 0
    Message from Sylvia on
    Hello everyone!

    Like all of you, SoundFont limitations are very problematic for me. They have not been updated for 14 years now, and ever since Creative abandoned the original X-Fi, 2.04 has been the last version.

    The only real solution to this issue is to make a new format that is not bound by this limitation.

    Do you want to work on a new standard with me?

    https://sites.google.com/site/strixsound…dfont-format-version 
  • PG 9 1
    You're clearly a fan of all those limitations...

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