Question of the Month: Lossless Conversion
Q. Is there a way by which the MP3 format can be converted to a lossless format in the true sense? What is the best method of converting analogue signals to a digital format without compromising fidelity? — B.P.B.
A. Thanks for your interesting email questions.
The answer is no, an MP3 file by definition has already thrown away a great deal of data that cannot be recovered.
To convert analogue signals to a digital format without losing data or compromising fidelity, you have to use a WAV or AIFF file format. Either of these will preserve the PCM data stream and introduce no compression or losses, but the files will be large—about ten times the size of a lossy MP3 file.
That said, there are several lossless compression formats that will use much less space, and preserve audio quality. The space reduction is about two to one, so the files will be about half the size of a WAV or AIFF file. They are FLAC (Free Lossless Audio Codec), Apple Lossless (ALAC) or WMA Lossless (Windows Media Audio Lossless).
You must start with the original signals, either analogue or a digital PCM bitstream from a CD. Encoding those signals in FLAC, ALAC or WMA (Lossless) will not compromise fidelity or throw away irretrievable data.
I'd also add that if you run MP3 at relatively high data rates such as 320 to 360 kbps (kilobits per second), the audio quality will be very good for all but a few esoteric instruments (harpsichord and castanets). I can say this with some authority, as I was a member of the listening panel auditioning many lossy and lossless codecs 15 years ago for the Canadian Broadcasting Corporation at the Department of Communications in Ottawa, Ontario. The experiments conducted in Canada were repeated by the BBC in England and ABC broadcasting network in Australia and reached the same conclusions as the Canadian listening panel.
About the Author
Alan Lofft was, for 13 years, Editor in Chief of Sound & Vision, Canada's largest and most respected audio/video magazine. He edited Sound & Vision (Canada) until 1996, when he moved from Toronto to New York to become Senior Editor at Audio magazine.
Lofft has been writing about hi-fi and video professionally for over 20 years, ever since his first syndicated newspaper column, "Sound Advice", began appearing weekly in The Toronto Star, Canada's largest-circulation daily newspaper. In the late 1970s, he became a contributing editor, columnist, and equipment reviewer at AudioScene Canada, the leading national consumer electronics magazine at the time.
He also wrote on consumer electronics for Maclean's magazine and made occasional appearances on TV on "Canada AM," the national CTV morning show, and on June Callwood's national afternoon TV talk show.
In 1983, he was appointed editor of Sound Canada magazine, which he relaunched in 1985 as Sound & Vision, incorporating video content and reviews as well as hi-fi and audio features. He also became a contributing editor to Stereo Review in New York, and an audio columnist for Music Express, a Canadian rock magazine.
An audio and electronics enthusiast from childhood, Alan began building vacuum-tube hi-fi gear for his father, who was an audiophile in the 1950s. Lofft's passion for audio continued through college, during which time he hosted and produced "On Campus", a radio show taped on location (on a portable Ampex 650 open-reel recorder) at Wilfrid Laurier University and broadcast locally in Kitchener, Ontario.