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High Speed Audio Cassette to MP3 Conversion?

Posted by Cliff on from the quantity-over-quality dept.

tottydoc asks: "I have a few thousand cassette tape recorded lectures (monoaural) that I wanted to convert to MP3. Are there any high speed dubbing decks to use in combination with some software to do this quickly?" Might there be some quality concerns when recording audio to disk and then slowing it down to the intended speed?

1 of 17 comments (clear)

  1. Fiddle with the sample-rate... by cnvogel · · Score: 5, Informative

    Let me assume that those lectures are not hi-fi recordings and as such you could live with half or a quarter of the audio-bandwidth of your soundcard... Then lets assume that your fast-dubbing-tapedeck runs at four times the normal speed...

    Then just grab the signal from the playback-deck and feed it in your soundcard. Record it to a .wav file at 44100 Samples/sec and then encode it with your favourite mp3-encoder telling him that you have a 11025-Samples/sec (=44k1/4)recording.

    Now the encoded mp3 should have the correct speed and frequency again.

    Of course that would limit your Bandwidth to about 5000 Hz but I'd give that method a try to check the feasibilty of that method.

    If it works out halfway useable then you could try and get one of those 96kHz/24Bit-soundcards, that should yield about 12kHz Bandwidth (96kHz recording, 24kHz encoding -> 12kHz BW) which should be more than what you could expect from a normal analog audio-tape.

    Of course this totally ignores any frequency dependant effects in the path from the magnetic media to your computer... you may have to compensate these with some filters... maybe there are encoders that have an equalizer simmilar to the mp3-players?

    To check your recording's quality I'd recommand baudline (http://www.baudline.com/)