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Topic: Lossless encoding of audio from tape (Read 2763 times) previous topic - next topic
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Lossless encoding of audio from tape

I'm soon going to be copying a IEC Type I tape to my computer and I would like to know what the best settings I can use for FLAC. Is it OK to record in 16-bit, 32000 Hz and (after removing the silence at the beginning and end of the tape and normalising) encode that straight to FLAC? The tape's guaranteed to not have any frequencies above 15000 Hz (It's IEC Type I/Normal Bias) so, to me, it looks safe. To me, it seems like a waste of data to use 44100 Hz on something that doesn't even have it. If anyone can tell me why it would be better to use 44100, let me know. Other than that, I guess I'll just use that. Thanks for whatever info you give me on this...

Lossless encoding of audio from tape

Reply #1 –
I'd use 44.1khz if you plan burning an AudioCD with the contents of the tapes later. Experiment how big the size difference between 33.2khz and 44.1khz are (compressed with flac).
"To understand me, you'll have to swallow a world." Or maybe your words.

Lossless encoding of audio from tape

Reply #2 –
sample-rate conversions are not particularly nice for sound.

if there's nothing above 15k, then it can be lowpassed and you'd probably gain a lot of compression in FLAC (possibly even comparable to recording in 32khz).  however, i'm not sure if it is guaranteed to not have anything over 15k.  transients could probably give you stuff in this range.  i've seen 30 year old cassettes produce frequencies this high (although i'd say they were the products of distortion, and only occured on transients).

however, tapes with a high noise content will not compress well in any lossless codec.  noise is noise - randomness, and that can't be predicted well at all.

if you can record in higher than 16 bits, that would also be good (you never know when you'll want to noise reduce, or apply some dynamics processing on it).  if you're normalizing, you'll want as much precision as possible.

don't bother with dithering down to 16 bits however - there will be more than -90dB noise in the tapes

Lossless encoding of audio from tape

Reply #3 –
Quote
sample-rate conversions are not particularly nice for sound.

if there's nothing above 15k, then it can be lowpassed and you'd probably gain a lot of compression in FLAC (possibly even comparable to recording in 32khz).  however, i'm not sure if it is guaranteed to not have anything over 15k.  transients could probably give you stuff in this range.  i've seen 30 year old cassettes produce frequencies this high (although i'd say they were the products of distortion, and only occured on transients).

however, tapes with a high noise content will not compress well in any lossless codec.  noise is noise - randomness, and that can't be predicted well at all.

if you can record in higher than 16 bits, that would also be good (you never know when you'll want to noise reduce, or apply some dynamics processing on it).  if you're normalizing, you'll want as much precision as possible.

don't bother with dithering down to 16 bits however - there will be more than -90dB noise in the tapes
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Thanks for all this information. There's not much distortion on the tapes I'm copying. I forget -- What do you mean by 'transients'? With my current sound card, I can't record higher than 16 bits, so that's out of the question.

Lossless encoding of audio from tape

Reply #4 –
Quote
I'd use 44.1khz if you plan burning an AudioCD with the contents of the tapes later. Experiment how big the size difference between 33.2khz and 44.1khz are (compressed with flac).
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I'm assuming you meant 32 kHz?