Upsampling Information

[RobGoodison]

This is my upsampling workflow - using Audiofile Engineering's Sample Manager 3 program to convert my standard 16/44 AIFF files to 24/96 AIFF files.

 

The reason for doing this? To my ears, in my system, the upsampled files sound better than either Amarra Junior playing them as 16/44 files, Pure Music's software based realtime upsampling to 24/96, or configuring Audio MIDI to 24/96 and relying on Core Audio upsampling.

 

My system:

 

Mac mini 2010 (stock 2.4GHz cpu; 2GB RAM; 320GB HDD; OS 10.6.6.).

External Western Digital 2TB HDD connected via USB.

Tacima CS929 Mains Conditioner/RFI Filter.

Silver C7 Connector Mains Power Cable.

Apogee Duet DAC/Headphone amplifier.

Oyaide neo-w d+1394 9pin - 6pin firewire cable (0.6M length).

Denon AH-D7000 headphones.

 

A few points:

 

1. YMMV - like most things in the audiophile world, it can be system and user dependent - some may hear an appreciable difference; others may not.

2. My 6000 track iTunes library as 16/44 AIFF files consumed around 260GB of storage space; converted to 24/96, it now consumes 780GB of space.

3. I had a backup of the 16/44 files before attempting this.

4. The program has a 15 day demo available. I'd suggest trying it on a few well known/loved albums across genres, to see if it suits before rushing headlong into the conversion process.

 

Anyway here's what I do:

 

1. Importing CDs into iTunes - ripping to AIFF, error correction on.

2. Adjusting metadata to taste.

3. Removing tracks/albums from iTunes, but not deleting the files.

 

(The above might not suit other peoples workflow, but I find iTunes so much easier when it comes to editing metadata).

 

4. Move the files from the iTunes Music to my desktop.

5. Open up Audiofile Engineering's Sample Manager application (http://www.audiofile-engineering.com/samplemanager/).

6. I have the following Actions defined as the workflow within Sample Manager:

 

a. Convert Bit Range (Range = 24bit; Dither = None; Destination Options = In place).

b. Convert Sample Rate (Rate = 96000; Resample = Yes (tick); Converter = iZotope Resampler; Quality = High; Destination Otions = In place).

 

7. Drag audio files from the Desktop into Sample Manager's File pane.

8. Wait until the program analyses the waveforms (can be disabled from the programs Preferences, if required).

9. Select the files in the pane, then click the green Run button in the toolbar.

 

 

 

What happens next is a two-stage conversion to the files - firstly converting the files from 16 to 24 bits, then converting the sample rate from 44.1kHz to 96kHz.

 

(A word of warning - make sure you have plenty of hard-drive space available. Deselect the 'Enable Undo' option in Sample Manager preferences will save space too).

 

10. Once converted, add the converted files back to the iTunes Library.

 

(My Audio MIDI settings are set to Apogee Duet 24/96 - I'm using vanilla iTunes at the moment).

 

Hope that helps.

 

Rob.

 

[blueixus]

It generally considered than conversion from 44.1kHz to 96 kHz is 'hard maths' rather than conversion from 44.1kHz to 88.2 kHz which is 'easy maths'.

 

My listening test between these two definitely favour the 88.2 kHz sample rate - of course 176.4kHz would also be worth trying.

 

 

[Bob Stern]

Audiofile Engineering makes a similar product called Wave Editor.

 

The downside of Wave Editor compared with Sample Manager is that it lacks batch processing and AppleScript support, but it should be possible to overcome that with GUI scripting.

 

The intriguing feature of Wave Editor is that the low-pass filter used for sample rate conversion is much more configurable than in Sample Manager. You can adjust cutoff frequency, steepness, and ratio of pre-ringing to post-ringing. I think it would be interesting to try reducing the ringing by choosing a lower cutoff freq, low steepness, and zero pre-ringing. This would be similar to the custom filter in the Ayre QB-9.

 

[RobGoodison]

96KHz or 88.2 kHz

 

I believe the iZotope 64-bit SRC that Sample Manager uses doesn't have issues converting to non-integer sample rates, but if 88.2kHz sounds better for you/your equipment that's good news, and will save some HDD space too.

 

 

 

[Blu]

Thanks Rob for posting about Sample Manager, I tried the 15 day trial recently and have purchased it.

 

I first read about its sister program Wave Editor at Audio Circle, see the following http://www.audiocircle.com/index.php?topic=69069.0 where you'll find comments from audio engineers on the quality of its output, some of these engineers have posted here at Computer Audiophile. They all comment on the quality of the iZotope Resampler.

 

I prefer the sound of music in the WAV format so I use it instead of AIFF, but I use the same procedure as you but take the sample rate to 24/88.2, as I prefer its sound to 24/96, in my system. I would take it to 24/176.4 but it doubles the amount of disc space required, it's something I'm still mulling over as hard disk space is so cheap.

 

Apparently it will also upsample to 176.4, but you have to manually put in 176400 as it is not on the drop down list.

 

[audiventory]

Quality upsampled sound depend of equipment ("To my ears, in my system" - as say RobGoodison).

 

Theoretically up-sampling is useless (don't add more information about waveform). With low-quality of sampling rate converter even it is harmful.

 

But sound card driver or hardware make realtime sampling rate conversion (SRC) all files, which have unsupported by soundcard's internal sampling rate. Real-time SRC commonly worse (very great computation loading), than non real-time SRC (using sampling rate converter).