Audio editors

Introduction

Speed
Speed is an AudioSuite plug-in that changes the pitch or the tempo of audio files from within Digidesign Pro Tools. Just select an audio file in Pro Tools’ Edit window and choose Speed from the Audio Suite menu. The Simple Control window appears with two rotary buttons: Speed, which controls tempo; and Pitch, which, yes, controls pitch. Two buttons – Preview and Process – let you preview then process the selected audio and save the results to disk. Various modes are available in the Calculator Panel, such as Key, Tempo, or Length. Alternatively, Speed’s unique Graphical Control Panel displays the audio waveform with two horizontal-graph lines that can shift pitch or tempo. You can use these to correct pitching or timing, or to create accelerandos and decelerandos within tracks. Speed is great with drum loops. I changed the tempo of a drum pattern all the way from 50 per cent to 200 per cent and it sounded perfect. Speed is not as good with vocals – pitchshifting moves the vocals formants as well. When I took Carol King’s recording of It’s Too Late and shifted it by two semitones, I could hear a sort of warbling- sound on the voice and saxophone. But, for trying ideas out in Pro Tools, with any kind of audio material, Speed is the ideal tool to use. Time Factory
Time Factory is stand-alone software for time-stretching and pitch-shifting final mixes, or other sensitive audio material. When launching Time Factory, you’re presented with the Batch List window where you can open a single mono-audio file, split-stereo files, or multiple files. Each file appears as a horizontal bar, divided into columns displaying edit parameters. You can alter pitch in semitones or cents, or alter length in seconds or percentages. Also the speed can be changed in beats per minute (BPM). Checkboxes for each file let you choose either Preserve Formants or Transcribe Mode – a unique feature that creates a file which plays back at half speed, while keeping the pitch the same. This makes it much easier to transcribe the notes by ear. Formants are characteristic resonant-frequencies of the human voice or of particular musical instruments. They stay the same even when you sing or play different notes in real life. Time Factory lets you emulate this behaviour when you pitchshift – leaving formant frequencies untouched. I took a 100BPM, four-bar drum pattern and changed the BPM down to 50 and then up to 200. The results were not quite as good as those with Speed – a sort of “thwocking” sound appeared on the snare at 50 per cent, while at 200 per cent the congas sounded “slappier”. When I pitchshifted Carol King’s recording of It’s Too Late, results were comparable with those from Speed. But when I pitchshifted a solo voice and a solo guitar, each time choosing the Preserve Formants option, the results were faultless. Mike Collins
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