Quicktime pro resampler quality? Options

[Mix3dmessagez]

I use quicktime to downsample needledrops to 48hz tvbr *for ipod use*
I've also come across foobar sox resampler which I've read is the best
I've tried to do comparisons *downsample with sox to 48000hz then convert with quicktime or convert using quicktime*
Usually the bitrates will be the same *on average* however sometimes sox downsamples will be one bit higher *on average*
I've tried to look at the individual bitrates for the first few seconds of each song *Just to see if there's a conclusive difference* and they seem to handle things quit differently, I notice the bitrate changes faster when downsampled with sox, I know that probably isn't a determinant as to quality, but it's all I know
With sox I use very high, 48000hz, 95% passband, allow aliasing, 25% phase response *someone at another forum said those are best settings*
On quicktime, best quality, variable bit rate, and recommended sample rate
I also want to know as if Sox is better I can resample all needledrops to 48hz flac *from 96 to save space*

[SebastianG]

I don't know about how well Quicktime does resampling. I just wanted to comment on some things here.

Mix3dmessagez, it seems you're lumping two processes together into one. Downsampling is the process of reducing the sampling rate. Encoding is -- in this context -- the process of turning a PCM signal into some other compressed format.

I guessing that you're trying to convert a 96 kHz signal into a compressed 48 kHz signal. So far so good. Just pick a decent resampler for downsampling (at least sox qualifies as such) and a decent encoder for compressing the downsampled signal.

With sox I use very high, 48000hz, 95% passband, allow aliasing, 25% phase response *someone at another forum said those are best settings*

Sounds like overkill to me. Though, I don't know what "25% phase response" is supposed to mean. A 20 kHz pass band (84% for fs=48000 Hz) is probably sufficient. Allowing a little bit of aliasing above 20 kHz is ok, I guess. The content above 20 kHz is likely to be removed during compression anyways.

This post has been edited by SebastianG: Mar 29 2012, 10:36