[Chef Medeski]

Quote:

Originally Posted by lionel marechal <Bit-Rates/Codecs used: Simply list like such. Say VBR for variable bit-rate and CBR when its something like Lossless (Changing Bit Rate) It just means that itll pretty much change for every song> Sorry but you have the wrong definition of CBR. CBR means Constant Bit Rate, by opposition to Variable Bit Rate. It does not mean lossless. So for example 128 , 160, 192, 256 and 320 are the base CBR rates for MP3. Lionel

I made up CBR just to mean a changing bit rate. Sort of like 320 is always going to be 320, but lossless is going to vary. I wasn't sure if it was VBR. But anyways, What should I change it to DBR? DIfferent Bit rate.

 

[pds6]

Constant Bit Rate (cbr)
Variable Bit Rate (vbr)

128 bit cbr = 128 bits (this is the floor and the ceiling).

128 bit vbr = 128 bits is the "baseline" and the bit rate well go up a little when the music passage needs more or down a little when the music passage needs less.

 

[DaKi][er]

On another forum, in discussions on audio codec's, someone did some tests converting a wave to a compressed format then back again and mathematically compared the difference between them and gave a list on the amount of difference calculated over a range of codec's and bitrates

The site is down at the moment but I'll find the table and post it here when i can

 

[Febs]

Quote:

Originally Posted by Chef Medeski I made up CBR just to mean a changing bit rate. Sort of like 320 is always going to be 320, but lossless is going to vary. I wasn't sure if it was VBR. But anyways, What should I change it to DBR? DIfferent Bit rate.

If you want to be serious about conducting a listening test to gather "objective data here from everyone to help people along," you can't make up definitions for terms that are contrary to their commonly-accepted meanings. That is going to lead to more disagreement, not less.

As was pointed out earlier, your proposed test is entirely subjective. If you'd like to get an understanding of what it takes to design an objective test, I'd suggest you read this section of the Hydrogen Audio knowledge base.

 

[DaKi][er]

Finally found it - and here is the link back to the original post http://forums.overclockers.com.au/sh...70#post6564770
Quote:

Originally Posted by chancey @ OCAU forums I couldn't find software that will let me compare the sound quality of two WAVs on the web, so I wrote a program that does this. I did this: 1. Rip a CD track with WAV 2. Convert to lossy format (eg. ogg) then back to WAV 3. Compare the 2 WAVs with a difference algorithm (very simple algorithm to find a numerical value on how different the waves are) I couldn't test MP3 or some AAC formats, dont know why, when I convert them back to WAVs the wav difference algor gets crazy results. I don't know how accurate these results are, but the track I used was E.S. Posthumus - Cuzco: Code: [left]FLAC (compression: 8)ABR8070.000% Monkeys Audio (compression: insane)ABR8110.000% Monkeys Audio (compression: normal)ABR8240.000% WMA LosslessABR8320.000% Apple LosslessABR8720.000% WAV UncompressedCBR14110.000% OGG Q10 (500 kbps)VBR4691.429% OGGCBR5001.429% WMACBR3201.855% MusePack (quality: braindead)VBR2662.225% MusePack (quality: insane)VBR2342.909% OGGABR2563.058% OGG Q8 (256 kbps)VBR2493.147% MusePack (quality: extreme)VBR2043.771% WMACBR1923.922% MusePack (quality: standard)VBR1734.911% OGGABR1924.955% OGG Q6 (192 kbps)VBR1815.339% AAC Quality 500VBR2855.580% AAC Quality 400VBR1986.305% WMACBR1286.387% MusePack (quality: radio)VBR1316.522% AAC Quality 300VBR1786.926% OGGABR1288.119% AAC Quality 200VBR1518.203% OGG Q4 (128 kbps)VBR1208.531% OGGCBR1288.531% MusePack (quality: thumb)VBR959.376% AACABR12810.340% AAC Quality 100VBR11211.828% MusePack (quality: telephone)VBR7112.484% OGG Q2 (96 kbps)VBR9112.690% WMACBR6412.971% AAC Quality 50VBR8217.959% OGG Q0 (64 kbps)VBR6020.110% OGGABR4821.786% AAC Quality 10VBR5244.410%[/left]

 

[craiglester]

Quote:

Originally Posted by DaKi][er Finally found it - and here is the link back to the original post http://forums.overclockers.com.au/sh...70#post6564770

Surprised to see no MP3 in there.. hmm odd.

AACABR12810.340%


Rhapsody I' led to believe is 160 CBR WMA so should be better than this

WMACBR1286.387%

and the new Zune Marketplace Is allegedly 192 Kbps WMA (not sure if that's CBR or VBR)


WMACBR1923.922%

(no rating on 192 VBR but it should be better than CBR - much better)

So this makes me think, isn't it about time apple upped their encoding to something better?

and NO I don't own an Ipod, Zune or Sansa (Rhapsody branded) player.

I'll stick with old faithful - my old clunky gapless Flac playing lovely sounding Karma

 

[HiFiRE]

Without ABX'ing, results such as these are flawed (to put it politely). People underestimate the placebo effect. It is simply to strong to ignore. There is ABX software available for mac, it's written in java and should work on most platforms. Google mac abx :O Here is a link to the app.

Edit: Also AAC has shown better results than LAME in many ABX tests.

 

[DaKi][er]

Quote:

Originally Posted by craiglester Surprised to see no MP3 in there.. hmm odd.

I didn't do the tests, it was just a straight copy and paste of someone else's experiment

A reason that mp3 probably isn't there is because of the way that it doesn't do gapless very well. As mp3's are encoded in small chunks at a time called frames, when it is converted from wav and back again there is some time offset as the frames stuff up the timings and this screws up the comparison algorithm where the guy said he has very screwed up results from them. Maybe it could be fixed up with some tweaking of the options in the LAME encoder, maybe mp3 is too flawed to get around it

 

[wanderman]

Quote:

Originally Posted by infinitesymphony Not necessarily. There are also lossy VBR MP3s. "Variable Bit Rate" does not equate to "lossless." For example, WAV files are CBR and lossless.

yes, lossless codecs are inherently vbr. Lossless is not the same thing as uncompressed. Done.

 

[breez]

Mathematically comparing the difference to uncompressed is not very relevant with psychoacoustic codecs. The comparison doesn't differentiate between the differences ie. some differences are more easily audible than others.

 

[bellsprout]

hmmm...for bitrates people actually listen to, the amount of loss is actually very little.

now i have a question:
do most of the losses come from the ripping or the encoding stage?

 

[breez]

Quote:

Originally Posted by bellsprout now i have a question: do most of the losses come from the ripping or the encoding stage?

None should come from the ripping.

 

[wanderman]

Quote:

Originally Posted by bellsprout do most of the losses come from the ripping or the encoding stage?

Most of the loss comes from encoding due to the algorithm the codec utilizes to discard inaudible information in psychoacoustic processing. Lame can do some strange things through processing like introducing the sandpaper sounding distortion.

 

[rhythmicmoose]

Quote:

Originally Posted by Chef Medeski Yeah... I'm on a mac, iTunes is like my only option.

iTunes is definitely not your only option! Hurry up and download Max before it's too late. Secure ripping to just about any codec imaginable.

http://sbooth.org/Max/

 

[bigshot]

I hadn't done a comparison test of compression rates since before Apple introduced AAC VBR. So yesterday, I sat down and ripped and compared and discovered that 192 VBR AAC works great for my purposes. Before this I was using 256.

See ya
Steve