Converting DAT recordings to computer files

Discussion in 'Mastering Engineers Forum' started by m_ahlenius, Jan 7, 2005.

  1. m_ahlenius

    m_ahlenius Guest

    Hi,

    I need to make some fairly high quality speech audio recordings at 16KHz, 16 bit linear audio format (*.raw).

    I tried recording right to a PC using a AT 4033 mic, a little Berhinger mixer and a PC - but the noise level was quite high and I think part of it may be because of the sound card in the PC. I don't know the make, it wasn't my gear. Plus I know that the sampling rate and 16 bit linear storage format does limit the dynamic range and quality of the audio output.

    We have a Sony 7040 DAT recorder and I thought about using it to do the recordings because it would surely have a better A/D and higher quality audio electronics as well. But once its on the DAT tape, are there any easy ways to get it back to a file format on a PC/Mac? If you just play out the DAT, you go back thought the D/A and then into the PC audio input A/D - so you may just re-introduce the quantization noise, etc.

    So I was looking for a way to take the DAT output directly to the PC so I could subsample it down to 16 KHz.

    Any suggestions would be appreciated.

    thanks

    'mark
  2. lucidwaves

    lucidwaves Guest

    If the PC has s/pdif input you should be able to transfer it digitally from the DAT recorder to the PC. That is the only way I think that you could get this done.
  3. m_ahlenius

    m_ahlenius Guest

    OK,

    another possible solution I just heard about was to use ProTools. I don't own that tool, and am assuming I'd need a much better sound card (if either the default PC or Mac one is not good enough).

    Is that a better approach? I rather doubt that any of our PC's have that PDIF input on them.

    thanks

    'mark
  4. lucidwaves

    lucidwaves Guest

    ProTools is an audio recording and tracking program. If your audio interface for the computer sounds like crap then all protools will record is that crappy sound from the interface.

    Get a decent audio interface for your computer (alot of them have s/pdif as well) and you will be able to get the job done the way you want.
  5. Javier

    Javier Guest

    M_ahlenius wrote:
    "Hi, I need to make some fairly high quality speech audio recordings at 16KHz, 16 bit linear audio format (*.raw)."

    Hi m_ahlenius;

    Since you have chosen 16khz sampling rate, you will have frequency limitations but no dynamic compromise since you will still be at 16 bit.
    Most sound cards that come with a pc are capable to record at this rate and the audio hardware you have mentioned (mike and board), IMMO has enough quality to do a fairly decent speech recording. I must also add that if you want to record, say at 44.1khz and then resample at 16khz, I donĀ“t know which editing program is able to do this. At least in Sound Forge 6.0 that task is not possible. However, the windows sound recorder does record at that rate.

    It would be helpful if you describe your PC hardware and audio software, although it sounds to me like a proper handling of levels issue.
    Also you should make Shure that you have your soundcard properties set to "optimal" and full hardware acceleration under the multimedia-sound devices dialog in windows operating systems. If you are recording from the "what you hear" source and, your pc microphone volume control is cranked up, you could get a lot of noise.(you can go to the playback mixer dialog and mute it). Do the same with de audio cd box too. It is much better to record from the "line in" source. You can check that box at the : level mixer-options-properties-recording dialog of the windows audio mixer.
    Finally, make shure you have near zero levels (-10 to -2db), throughout your audio chain.
    I hope this info will help you obtain good results.
    Best regards. Javier
  6. m_ahlenius

    m_ahlenius Guest

    sound card ?

    Hi all,

    thanks for the replies. Regarding buying a decent sound card for the computer - any suggestions?

    I am assuming that the sound card in most laptops are probably not the best ones out there. Again, I don't know the quality/brand of the one we had in that machine I did my tests on, as it wasn't my gear. I just know it was way too noisy.

    If someone can point me to a better card, that would be great. Also - what do you all think of the sound input quality of a powerboook machine? I do have my laptop which I could use for this and could do this with something like Audacity.

    thanks again,

    'mark
  7. JoeH

    JoeH Moderator

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    Good lord, don't go buying PTs just to do 16/44 DAT transfers! <G>

    THat's like buying a tank to drive to the corner store for bread. PT's is a huge investment, and fairly expensive. It's more of a lifestyle choice, a commitment to a format and way of working.

    For desktop computers, even the lowliest of the SB Audigy Platinum cards have SP/DIF inputs, so you can do the DAT transfers with a $100 SB audigy card, if you're under the gun. That'll do ya fine for now. 16/44 is fine for voice and most of what you're describing. Don't worry about anything higher at THIS stage of your development. You can move on and upwards later, if the thing grows on you.

    As for a laptop, you'll need firewire or USB interfaces to get audio in/out of your system. Don't even think about using those 1/8" inputs or outputs. Use 'em for Headphones at best.

    Edirol, Roland, M-Audio and many others make nice little 2, 4, and more input/output boxes for firewire/usb 2 ports. Find one of them with SPDIF (I'm fairly certain the M Audio F410 has that feature - I have the thing, but never used it for that....)

    There's lots of freeware out there to get started with for editing...you may want to try Mackie's Traction software (they give it away on their website) or Pro Tools LE. both work on PCs OR Macs, I'm told. There's a lot of other good stuff out there as well. Use google and type in: "Audio Editing Software Free" and see what you get.

    Good luck....its' easier than you think, once you get it up and running.
  8. m_ahlenius

    m_ahlenius Guest

    a few more ?'s

    Hi,

    thanks for the suggestions. I was thinking of just going and using someone else's PT solution, but would like to keep this as simple as possible.

    Given that I might be able to get a good cheap SB card you suggested for around 100 bucks or so , if I do my recording on a DAT drive (we have a Sony 7040), that records at either 48K or 44.1K (if not mistaken). So, is it easy with one of those sound cards or something like Sound Forge or Cool Edit to "cleanly" downsample to 16 KHz?

    That brings another question - when you set the sampling rate to let's say 16 KHz, does the SB card always record at a set frequency, but then the sw does a downsampling?

    Would I be better off to record directly into this "better" SB card with the sampling set to 16 KHz skipping the DAT altogether?


    thanks again

    'mark
  9. lucidwaves

    lucidwaves Guest

    I would just record from the mixer, directly into the sound card if I were in your shoes.

    Why does it need to be at 16khz sample rate? Its not going to sound great either way you record it simply for the fact that it is still going to end up at 16khz.
  10. m_ahlenius

    m_ahlenius Guest

    The reason that it is to be recorded at 16 KHz is that the digital samples will be used in a model at that rate. Granted 16 KHz doesn't sound as good as 48 KHz, but for low fidelity hardware, it works.

    Does anyone know for sure if the sound cards actually sample at the rate you set in a program like Soundforge or Cool Edit - or does the card always record at its higher sample rate and then the editing pgm downsamples?

    thx
  11. ghellquist

    ghellquist

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    Generelly the sound card records at the sample rate you set. But, if you record a digital signal it has to be recorded at that signal rate. Every recording program I have seen can do a SRC (sample rate conversion) with decent quality so that is not the large problem.

    So once the audio is inside the computer you can convert it to the new sample rate inside the computer.

    My suggestion is for you to get a decent sound card. Then transfer the signal from the DAT into the computer. You can do this either as an analog signal or as a digital signal. Me, beeing digital, like the idea of digital, so you need a soundcard with S/PDIF input. This comes in two flawors, either a small RCA contact or an optical contact. The other way is using audio cables which is also perfectly acceptable.

    Maybe you could borrow a sound card from a friend or something to save a bit of money?
  12. m_ahlenius

    m_ahlenius Guest

    Alright, so I have a Sony 7040 DAT machine but no manual. On the back the outputs are XLR for both digital and analog. So what type of connection does S/PDIF require - would it come from the digital XLR output of the 7040 deck?

    I am looking online for a pdf file of the 7040, as this might explain what I need, but have not found one yet.

    thanks for everyone's help!

    'mark
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