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Quicktime pro resampler quality?
Mix3dmessagez
post Mar 28 2012, 20:23
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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*
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Mix3dmessagez
post Apr 12 2012, 01:40
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QUOTE (nu774 @ Mar 29 2012, 00:05) *
If you are using MacOS X, you can try afconvert (CLI application), which lets you to control detailed parameters of CoreAudio SRC from command line options.
QuickTime is working on top of CoreAudio
[…]
In the past (at the time of QuickTime 7.6.5 or so), I have heard about audible aliasing problem of QT AAC sample rate converter from a HA user.
I suppose it doesn't have such a serious one in the recent versions, but I cannot say for sure.

I use windows sadly, but I tested this by converting to apple lossless in qucktime and on itunes.I then converted both to quicktime, and compared with the directly downsampled from aac quicktime.They all had the same exact bitrate, this leads me to believe that the downsampling is exactly in the same in quicktime, itunes, and aac codec within quicktime.

The latest windows version is 7.7.1, so I assume whatever issues present would either be fixed or atleast tweaked from that far back *hopefully*

QUOTE (SebastianG @ Mar 29 2012, 05:35) *
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.
[…]

Sox is what I'm comparing to quicktime, I am trying to decide between which of the two is better, I already have converted all my rips and downsampled in quicktime, and am trying to see which is the better choice.I've heard great things about sox, and made this thread to find out more about quicktime to see how it stacks.

QUOTE (Wombat @ Mar 29 2012, 11:58) *
QUOTE (SebastianG @ Mar 29 2012, 10:35) *
Though, I don't know what "25% phase response" is supposed to mean.

It is an audiophile attempt to solve a problem we canīt hear. With telling sox to use 25% phase response you try to get rid of the "pre" ringing around fs/2 and trade it against lots more "post" ringing. This is meant to sound much better. The little detail that you alter the signal completely into the audible signal of cause doesnīt count smile.gif

Hmmm, well if that's the case I assume it's better that way than normal, just to be on the safe side to have the best options enabled?

QUOTE (Wombat @ Mar 30 2012, 22:15) *
I am with Sebastian here that choosing parameters that preserve frequencies above 20kHz should be enough for us humans and this can be reached without violating the phase response. So even IF ringing was audible it shouldnīt be of an issue with some gentle chosen setting as you can see. […] Still i am waiting for some serious ABX results since my own told me i canīt ABX garbage from ringing smile.gif
[image]

I have uploaded two samples, both 25 seconds, one downsampled and dithered in foobar with sox resampling to 48000 with 95% passband, very high quality, aliasing allowed 25% phase response.
The quicktime one, no dithering or downsampling bits in foobar *and instead did all in quicktime*, and downsampled from 96000 to 48000 *in quicktime*, allowing quicktime to completely handle the dithering and downsampling, and bit depth *To fully access its functionality*

Quicktime
http://www.mediafire.com/?hgjv2mfu8b095w2
Sox
http://www.mediafire.com/?xcdj0hj7yawio0g

I would like any of the amazing audio enthusiasts here to see if you can hear a difference, as I know many of you are listening on much better equipment with ears for detail and everything more than I do.Please post your results!

This post has been edited by db1989: Apr 12 2012, 09:32
Reason for edit: Please do not unnecessarily quote entire posts; edit them to the relevant sections.
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Posts in this topic
- Mix3dmessagez   Quicktime pro resampler quality?   Mar 28 2012, 20:23
- - DVDdoug   QUOTE *someone at another forum said those are bes...   Mar 28 2012, 20:48
- - IgorC   http://src.infinitewave.ca/ has Apple resampler i...   Mar 28 2012, 21:20
- - Mix3dmessagez   QUOTE (DVDdoug @ Mar 28 2012, 15:48) [gia...   Mar 28 2012, 22:27
|- - saratoga   QUOTE (Mix3dmessagez @ Mar 28 2012, 17:27...   Mar 28 2012, 23:19
|- - Mix3dmessagez   But what if the source material is digital and pre...   Mar 28 2012, 23:29
|- - saratoga   To be clear, I'm saying that the process of cr...   Mar 28 2012, 23:31
- - nu774   If you are using MacOS X, you can try afconvert (C...   Mar 29 2012, 05:05
- - SebastianG   I don't know about how well Quicktime does res...   Mar 29 2012, 10:35
- - Wombat   QUOTE (SebastianG @ Mar 29 2012, 10:35) T...   Mar 29 2012, 16:58
- - Wombat   I hope it is of some help. I did some simple examp...   Mar 31 2012, 03:15
- - Mix3dmessagez   QUOTE (nu774 @ Mar 29 2012, 00:05) If you...   Apr 12 2012, 01:40
|- - nu774   If you are interested, now qaac lets you play arou...   Apr 12 2012, 03:26
- - Wombat   If there really someone was interested in listenin...   Apr 12 2012, 02:14
- - Mix3dmessagez   QUOTE (Wombat @ Apr 11 2012, 21:14) If th...   Apr 12 2012, 04:23
|- - nu774   Try something like the following QUOTE -V 127 --na...   Apr 12 2012, 05:08
|- - Mix3dmessagez   Hi, thank you so much!I see you are the creato...   Apr 12 2012, 05:35
|- - nu774   Still getting errors? See what foobar2000 says on ...   Apr 12 2012, 06:41
- - nu774   Ah, I've forgotten one thing: You will need ...   Apr 12 2012, 06:49
|- - Mix3dmessagez   QUOTE (nu774 @ Apr 12 2012, 01:49) Ah, I...   Apr 12 2012, 06:56
|- - nu774   QUOTE (Mix3dmessagez @ Apr 12 2012, 14:56...   Apr 12 2012, 07:25
|- - Mix3dmessagez   thanks, solved my issue!last problem though, I...   Apr 12 2012, 07:39
|- - nu774   QUOTE want quicktime best vbr but in its quicktime...   Apr 12 2012, 08:09
|- - Mix3dmessagez   I'm sorry for being unspecific.I'll try to...   Apr 12 2012, 08:37
|- - nu774   Well, it's interesting. Quickly tried now QT p...   Apr 12 2012, 09:45
|- - Mix3dmessagez   QUOTE (nu774 @ Apr 12 2012, 04:45) Well, ...   Apr 12 2012, 21:55
|- - nu774   QUOTE (Mix3dmessagez @ Apr 13 2012, 05:55...   Apr 13 2012, 02:31
|- - Mix3dmessagez   QUOTE (nu774 @ Apr 12 2012, 21:31) QUOTE ...   Apr 13 2012, 02:50
|- - nu774   QUOTE (Mix3dmessagez @ Apr 13 2012, 10:50...   Apr 13 2012, 04:53
|- - Mix3dmessagez   QUOTE (nu774 @ Apr 12 2012, 23:53) QUOTE ...   Apr 13 2012, 05:37
|- - nu774   QUOTE (Mix3dmessagez @ Apr 13 2012, 13:37...   Apr 13 2012, 07:11
|- - Mix3dmessagez   QUOTE (nu774 @ Apr 13 2012, 02:11) QUOTE ...   Apr 13 2012, 07:23
|- - nu774   QUOTE (Mix3dmessagez @ Apr 13 2012, 15:23...   Apr 13 2012, 08:07
|- - Mix3dmessagez   QUOTE (nu774 @ Apr 13 2012, 03:07) QUOTE ...   Apr 13 2012, 09:14
|- - IgorC   QUOTE (Mix3dmessagez @ Apr 13 2012, 05:14...   Apr 13 2012, 16:44
- - Wombat   Better ask on some audiophile forum for an abx of ...   Apr 13 2012, 14:06


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