What device will let me bit perfect record USB output?

[ADD]

Hi,

I'm new to all this ancilliary hardware that can be used with a computer, so I am not really sure whether I need some sort of digital recorder or whether a suitably featured USB interface will do the trick.

I have the following scenario. I have a digital output coming from my PC USB port (at 48 khz sampling rate). I want to be able to make a bit perfect copy of exactly what is coming out of this USB port and be able to save that as a PCM WAV file on the same computer.

I also have an optical SPDIF output on my X-Fi soundcard and I am pretty sure what is coming out of that would be the same as what is coming of the USB port (but I can't be certain, would it be??). Anyway, I say that because a I guess a bit perfect copy of what comes out of the optical port might acheive the same thing.

Just an example of what I have so far: I have a Zoom H2 recorder that can function as a USB interface, but can't actually make any sort of recordings or copies in this mode. But when I run it in this mode and monitor the output, the sound I am hearing out of this interface is precisely what I want a bit perfect copy of.

The other requirement as mentioned earlier is that I need this bit perfect copy to end up as a PCM WAV file on my PC.

Of course, I can already make a recording of what I hear using my X-Fi soundcard and it will of course produce a WAV file on the PC. But there is a quality loss doing this which I am wanting to avoid.

Thanks for any help.

 

[1UP]

??? This makes no sense - if your source is PC via USB, that means your source is either on file on that PC or is being routed through that PC successfully; either way it can be transcoded...on that PC...with any audio program

 

[jiiteepee]

X-Fi does have feature called "bit-matched mode" for recording/playback you could use w/ proper recording software (maybe ASIO capable software).

Creative Labs Europe Knowledge Base - Customer Support KnowledgeBase, Troubleshooting, and Technical Articles

EDIT: But as the X-Fi can't read USB output directly, you'll need some additional device (PC USB -> <USB dev w/ S/PDIF output> -> X-Fi) as like the HAGUSB converter.

Hagerman Technology LLC: HagUsb USB to SPDIF Audiophile Converter

jiitee

 

[ADD]

Quote:

Originally Posted by 1UP /img/forum/go_quote.gif ??? This makes no sense - if your source is PC via USB, that means your source is either on file on that PC or is being routed through that PC successfully; either way it can be transcoded...on that PC...with any audio program

It is being routed through the PC via a DSP processing chain, so the file does not exist per se - it is being created on the fly in real time. What I want is a bit perfect copy of what I am hearing after the output has been processed by the DSP chain. Any attempt to capture this using the PC or rendering an output file using any software program results in an output file of lower quality than what I am hearing in real time.

 

[ADD]

Quote:

Originally Posted by jiiteepee /img/forum/go_quote.gif X-Fi does have feature called "bit-matched mode" for recording/playback you could use w/ proper recording software (maybe ASIO capable software). Creative Labs Europe Knowledge Base - Customer Support KnowledgeBase, Troubleshooting, and Technical Articles jiitee

Hi,

Thanks, but I have already tried that. As an example, using bit perfect mode and ASIO drivers to make a recording still results in an inferior copy of the original streamed output.

In any case, after lengthly discussion with an audio engineer this afternoon, it appears that what I want does not exist. He suggested using a 48 khz capable digital recorder with an SDPIF input - either a flash recorder so I can upload from the flash card or a CD version so I can retrieve the file from a data CD.

I would still like to know why it isn't possible to capture the sound from the output stream on the PC itself and for there to be no audible difference from what I am hearing though.

Whilst the external recorder solution should work, it's a very expensive solution.

 

[hanalei mike]

If you get a mac, you can use wiretap. It will record anything your computer can play, and you can save to itunes or anywhere else. I believe up to 192kbps.

Maybe there is an equivalent in the pc world. good luck

 

[jiiteepee]

Quote:

Originally Posted by ADD /img/forum/go_quote.gif It is being routed through the PC via a DSP processing chain, so the file does not exist per se - it is being created on the fly in real time. What I want is a bit perfect copy of what I am hearing after the output has been processed by the DSP chain. Any attempt to capture this using the PC or rendering an output file using any software program results in an output file of lower quality than what I am hearing in real time.

If you mean you use X-Fi DSP effects in your chain and like to record that output then,
- have you tried the virtual audio cable meant for creatives' ASIO card Velbac - Sends audio from a Creative soundcard to another soundcard - DriverHeaven.net (you need 2nd card for recording)

or, if you meant to record virtual effects (wet signal) then here are couple possible methods:
1. Hermann Seib's VSTHost can record "what it plays" in realtime to up to 32f resolution
- you can add multiple effects in series or chain
2. Voxengo Recorder VST can be set to capture the software output (just put it last on chain ...)
- uses MME device for rendering to file (I don't know the implementation (does the stream go through kmixer?))
- works even w/ Foobar/Winamp/etc. if you use VST Host DSP plugins (for multiple DSP plug-ins, effects chainer/rack or eXT/bidule/console (as VST) is needed)


jiitee

 

[ADD]

Hi,

They are VST effects, so I guess the latter of your suggestions would be something worth trying.

At the moment, the "best" result I get is if I record the sound I hear using the ASIO recording functionality that was packaged with the X-Fi card. But I can still hear much I am losing doing it that way. There is a slight hardening up of the instrumental textures compared to the original.

Both applications I am trying (Plogue Bidule and Audio Mulch) both have rendering and record options, but both also produce an inferior PCM copy like the ASIO recording functionality does.

Anyway, I will give those products a try and see if they give a better result. Failing that I guess I will need to be looking for an external recorder.

 

[jiiteepee]

Quote:

Originally Posted by ADD /img/forum/go_quote.gif Hi, They are VST effects, so I guess the latter of your suggestions would be something worth trying. ...

Though the Voxengo Recorder works well, IMO, the Sieb's VSTHost is better for this type tasks ... I used the VSTHost software for to play/rip vinyls (in my PC setup, I use a RIAA VST filter I've prepared, instead of hardware RIAA stage so, the RIAA EQ needs to be done real time just before playing/recording) ... but, as now I have prepared full software for this functionality... .

jiitee