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adjustable_beatmarks

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This page shall document how implementation of adjustable beatmarks works.

Description

Beatmarks and measuremarks help especially beginners to beatmatch two songs and help to decide which track is ahead and should be delayed a tip. Since in most cases the beat doesn't start counting from the beginnig of the track, beatmarks require an offset. For this purpose this feature adds a MIDI signal that places a special cue (the “beat cue”) at current play position if send. The beatmark renderer afterwards calculates all marks foreward and backward to the beginning of the track based on BPM. Measuremarks are aligned in a way that beat cue is a measuremark.

Thus prior mixing someone adjusts beatmarks of both tracks by evaluating beats and measures and mark them precisly similar to conventional cues. Afterwards no trained ear is requiered to decide which track is ahead.

As hint by Lukas Smith: On a track with variable BPM it might be a good idea to set the beat marker at your mix out position and adjusting the songs BPM to the BPM at the mix out point, since at the mix in point you have plenty of time to beat match by ear

Signal flow

To adjust beatmarks send “beatmark_set” e. g. via Standard.kbd.cfg

Adjust beatmark

  • signal “beatmark_set” is send by ControlPushButton
  • slot BeatmarkSet is raised an signal “beatmark_point” is trigger with current sample position
  • waveformrendererbeat.cpp receives signal “beatmark_point” and adjusts beatmarks to current sample position

Track loaded

  • slot loadTrack is raised and cues are loaded from TrackInfoObject
  • beat type cue is sorted out and beatmark position is read and send to waveformrendererbeat.cpp

Track unloaded

  • slot unloadTrack is raised and cues are loaded from TrackInfoObject
  • beat type cue is sorted out and set to current beatmark position
  • cue dao should automatically save these changes in database

Changes

Touched files

  • player.h
  • player.cpp
  • dlgmidilearning.cpp
  • waveform/waveformrendererbeat.h
  • waveform/waveformrendererbeat.cpp

Added files

  • engine/beatmarkcontrol.h
  • engine/beatmarkcontrol.cpp

TODO

  • cues aren't saved after leaving MIXXX (general problem)
  • drawing button for skin
  • document about database issue beat type cue
  • mention files touched
  • describe what it's good for and how to use it
  • what about multiple beat type cues
  • managable cues? → change type
  • think about automatic beatmark adjust along bpm detection
Translations of this page:
adjustable_beatmarks.txt · Last modified: 2010/05/07 09:52 by mik