MP3 bit rates debate - can YOU tell?

DRZ

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I have three tests and I am going to release them one by one here. It is paramount you follow the instructions properly for it to be a fair test!

A few requests:

Please don't post what you think in this thread unless you "hide" it - your results mustnt hinder anyone else from making their own mind up.

If you have done this test for me before, you are welcome to have another go but again, please dont disclose the right answers :)

I cant tell you much about the test because the more you know the less accurate your brain is (a characteristic of the human brain always trying to guess "correctly"

FIRST TEST

http://www.statichiss.co.uk/CDvsMP3.zip

Download that zip file and BURN THE ISO TO CD!. Decompile the ISO all you want but at the end of the day "getting it right" isnt the aim of the game, there is no prize, just a clearer understanding of the MP3 world. If you do bother to take it to bits, congratulations, you spoiled it for yourself :)

If you can tell me which bit rates are used for each track, I will be very impressed indeed, but for the benefits of the test, simply tell me if the track playing is better or worse than the track before and guess at the lowest bit rate used.


Once you have got the hang of it I will introduce you to part 2, which makes things a bit clearer again :)

_______________________________________________________________

Well, part 1 seems to have attracted some criticism for the type of music used. This is for a reason, I will do a spoiler post at the end telling you why etc. For now, here is part 2.

Part 2

This should be a little easier to tell...

http://www.statichiss.co.uk/CDvsMP3v2.zip

Same deal as before, burn the ISO to CD and have a listen. Which bit rate is which?
 
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I'll give it a shot next week. I have an important deadline next Tuesday, will probably sleep most of Wednesday. So I'll probably try it after :)
 

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lemonkettaz said:
I can.

treble on >160kbps mp3's is hideous.... loses all quality compared to orignal CD.

Why havnt you told me which track is which then? If it is so obvious, you should be able to tell me!
 

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lemonkettaz said:
opps...

p.s. im not good enough for the test

What do you mean by "not good enough"? You cant tell?

Keep an eye out for the results before I put up part 2 if you truly believe what you posted earlier ;)
 

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Real music? Brahms isnt real?

There are two more to come and there are reasons for the music choices used ;)

Considering everyone is so damn quick to slate low bit rate MP3s, everyone seems a bit reluctant to jump in here, dont you think? ;)
 
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Haven't really had the chance to listen to them properly as everyone in my house is asleep but at a relatively low volume I would say the first sample was lower quality than the second - although i have a sneaking suspicion you're gonna tell me otherwise ;)


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For sound testing, Classical is probably better since most pieces use quite a large range of frequencies. There's also a bit of debate between .mp3 and .ogg. Nothing tests treble like a flute/piccolo and nothing tests bass like a 32' / 64' Organ pedal :D

I have a go at the tests tomorrow afternoon as I have quite a good ear but it can be quite difficult to tell the difference between bitrates above 128kbps since the difference are more suttle than sub 128kbps. But to be honest classical music in a lossy format is just wrong (but I'll save that for another thread :p).
 

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Dunky said:
For sound testing, Classical is probably better since most pieces use quite a large range of frequencies.

Depends entirely on the instruments used. For example, a Clarinet produces no energy above ~22kHz, whereas Cymbals can still have audible harmonics at 103kHz (where the best measurement microphones in the world run out of linearity).

For the purposes of this test, we are assuming a frequency bandwidth of ~22kHz (the Nyquist limit of CD) so we can assume the frequency content of every instrument to be roughly similar in terms of bandwidth (although obviously harmonic content will differ significantly). Tonality therefore will only differ from that of CD and so any tonality changes may be used to pick out differing bit rates, if you feel you can notice any tonality changes ;)

FWIW, compressing distortion is far harder than compressing a nice clean flute note, for obvious reasons. Distortion also masks quality to a certain extent and for that reason it was explicitly decided not to be represented here :)
 
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DRZ said:
FWIW, compressing distortion is far harder than compressing a nice clean flute note, for obvious reasons. Distortion also masks quality to a certain extent and for that reason it was explicitly decided not to be represented here :)

Actually never thought of that, it's a good point. There will always be certain instruments that are difficult to compress nicely (such as Trombone, Organ and Harpsichord in Classical Music - my main forte (excuse the pun)). Right burnt the CD, shall report back shortly :)

EDIT: Right listened to all 6 tracks and I have my order of lowest to highest in quality. Although it pretty much based on two things I noticed - one of which I think gives away the lowest quality. I can try and pin a bit rate to them. But I hold off my results for just a wee bit longer until I get the ok to post em :)
 
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I mounted the CD using alcohol and listenned using my Grado SR80/Audigy 2. I couldn't tell any difference. I was genuinely surprised about that, so I ripped a few tracks I know really well (No Surprises, Radiohead, Apocalypse Please and Thoughts of a Dying Atheist, both my Muse) to 128 kbps and 320 kbps MP3. Again, to my surprise, I couldn't tell any difference (using shuffle to hide which was which).

I will burn the CD and try it on my hi-fi tomorrow, although it's only slightly above entry level stuff.

The music is very clean though, so easy to compress and not the best for showing up compression (although I can't use that excuse for my Muse songs). Also since you point out that it would be possible to tell the difference by examining the waveforms, you are admitting that there is a difference, even if few people would have the ears to tell.
 
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Hmm... CD2 is even cleaner, empty even. Not much data there to compress. My results for CD2 are (based on the first second only)-

1 - great
2 - good
3 - poor
4 - good
5 - great

and for CD1 (based on the last few seconds only)

1 - poor
2 - good
3 - average
4 - great
5 - great
6 - great

SR80 aren't exactly great though, and neither is an audigy 2.
 
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If you quote / code your own results and use the [color] tags to make them dark blue, it ought to make it so people need to highlight them to see. That way anyone reading the thread has to make an active choice to cheat.

As for me mentioning that if you decompiled the ISO you might see things etc, well, yes but the fact I am telling you this doesnt change the fact a difference is expected etc because it is fairly obvious from the rest of the post a comparison between tracks needs to be drawn. I dont feel this flaws the test, anyway.
 
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I do think it's very hard to tell because our short term memory is so limited. You can't really remember how something sounded in the previous track, even though they're only 36 seconds long, so it's difficult to make any comparison. Hence I've been just using the first few seconds of each. Not knowing the music doesn't help either.

Also there's some sort of reed instrument playing left channel on CD1 which sounds very similar to compression artifacts, which really doesn't help.
 
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Right, what colour do I have to use exactly to hide it cause I was playing around with preview post and I couldn't get the right colour. Also I thought you could hide it without having to put into a Quote/Code comment. Any handy hints and this post shall get updated with me results :)

EDIT: heh I can still see it with Navy and Quote...I'll upload it somewhere and post a link. Probably easiest way actually...

EDIT 2: According to a friend, it's hidden on their Windows Box so I'll quote with Navy then.


1 - 64kbit - At about 0:10-12, lack of the distinct tounging sound (in the left channel) during the clarinet downward scale gave this one away I think. All other tracks it was more distinct
2 - 96kbit
3 - 256kbit - Tracks 3 and 6 were very close. What I felt gave both of them the edge was the clarity of the mid/upper-range piano (middle C plus 2 octaves) and 'Cello/Contrabass lines.
4 - 160kbit
5 - 128kbit
6 -224/256kbit
 
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