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Comparing CD vs mp3 quality: which frequencies are lost in mp3s?!.. (pg. 2)
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| Atlantis-AR |
| quote: | Originally posted by Dance123
What I really would like know: what's the maximum frequency of mp3s (any difference in this between a 192 and 320kbps files) and vinyl. Anybody knows those numbers?!
Isn't it so that a CD sound brightest because it goes up to 22kHz and people can hear frequencies up to 20Hz (correct me if I am wrong) which a decent pair of hifi speakers can reproduce.
Anyway, I always get the impression that a 192kbps mp3 sounds less bright then a CDs, but I still don't know why that is! |
Yes, the maximum frequency depends on the bitrate, though it also varies slightly from file to file depending on the original frequency makeup. Use a spectrum analyser to find out the exact frequency and work out average values if you're really interested. From memory, a 128 kbps MP3 might throw away everything above 16 kHz, while a 192 kbps MP3 might have the LPF (lowpass filter) at 17 or 18 kHz. 320 kbps is probably around 20 kHz, or the LPF just has a gentler slope, can't remember.
Not only does compression to MP3 throw away the air frequencies, but it also screws up the rest of the frequency makeup, something you're definitely be able to hear after training your ears, and certainly if you've listened to CDs all your life and put on an MP3 track. And people can hear frequencies to about 16-18 kHz, yes. And depending on how youg or undamaged your ears are, this can go as high as 20-22 kHz,.
Well it sounds less bright because, one, the air frequencies above 17 kHz are discarded, and two, because the other frequencies (mostly audible in the highs) are affected too, adding 'swishy', 'flanging' artefacts that dull the sound and lose the sound's sparkle and transients. |
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| ZxZDeViLZxZ |
| i would hope vinyl wasnt pressed from a cd source... i would hope itd be pressed from the highest quality format availble and not from a cd... |
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| Dance123 |
Hi,
Great test, you can clearly hear the difference, but that's normal if you only use 128kbps. Perhaps you could do the same test with a 192kbps mp3 and perhaps also higher. Some say 192kbps sounds as good as CD, but I have my doubts, especially regarding high frequencies.
By the way, could you please explain the graphic, like what do the yellow and orange line mean? Also, your graphic seems to go only to 16khz so difficult to see what happens beyond that.
Last question: what's the name of that track and from which (compilation?) album did you take the sample. Sounds great, always looking for great new tunes! :) |
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| thecYrus |
| quote: | Originally posted by Dance123
Last question: what's the name of that track and from which (compilation?) album did you take the sample. Sounds great, always looking for great new tunes! :) |
Anjunabeats Volume Two
Smith & Pledger - Forever (Aspekt Remix)
i'll do the other test soon.. |
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| luizmenezesjr |
Hi Everyone,
Reading all posts, I make a test with WHITE NOISE (all frequencies with the same power)
The method was:
1-) Creating a source 24bits, 48kHz, Stereo WAV.
2-) Generating a WHITE NOISE with -1.0db (to avoid distortion)
3-) Saving the .wav as .mp3 in the formats:
Format - Size in bytes - Compression
Wav 24bits 48kHz - 288.046 - 0,00
MP3 128Kbps 44.1kHz - 18.288 - 15,75
MP3 128Kbps 48.0kHz - 18.432 - 15,63
MP3 192Kbps 44.1kHz - 26.856 - 10,73
MP3 192Kbps 48.0kHz - 27.072 - 10,64
MP3 320Kbps 44.1kHz - 43.392 - 6,64
MP3 320Kbps 48.0kHz - 43.993 - 6,55
MP3 VBR Highest 48kHz - 42.816 - 6,55
4-) Checking all the db frequencies on each file using a Fast Fourier Transform (FFT):
(click on the name format to download the mp3 or wav file)
Wav 24bits 48kHz
MP3 128Kbps 44.1kHz
MP3 128Kbps 48kHz
MP3 192Kbps 44.1kHz
MP3 192Kbps 48kHz
MP3 320Kbps 44.1kHz
MP3 320Kbps 48kHz
MP3 VBR Highest 48kHz
6-) Conclusion:
The MP3 Format removes high frequencies to compact the original wav source.
If you open any .mp3 format, you will notice a silence on the start and end of the file... So you may insert a silence on the start and end of the original wav to avoid loosing data.
If you want to distribute your files, you may use the MP3 320Kbps 48kHz format, because many high frequencies are still there after compacting.
But if you are working on 44.1kHz, the 192Kbps 44.1kHz is a good option too... Now it's up to you choose the best format...
You have to balance SIZE in bytes, and lost frequencies...
All my life I was using the Variable Bit Rate (VBR) Highest quality with 48kHz to compress my music, but now I see this format isn't good, because it looks like a MP3 128Kbps 48kHz but with low compression.
(sorry about my English) |
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| Atlantis-AR |
| Great test, luizmenezesjr. But I've got a better option: use OGG Vorbis instead of MP3. :rolleyes: It still discards the top-end, but when there are a lot of frequencies present here, it attempts to keep more of them. |
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| State of Matter |
| quote: | Originally posted by ZxZDeViLZxZ
i would hope vinyl wasnt pressed from a cd source... i would hope itd be pressed from the highest quality format availble and not from a cd... |
Think about how trance is produced man. From a whole bunch of digital audio. It is then exported to wav and the vinyl is pressed from this wav file, which is the equivalent of cd audio, 16 bit 44.1 khz. Sorry, but your argument doesn't hold water. |
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| Orko |
I am trying to convert some old tapes to CD.
I also wanted to record in 192khz/24bit, to maintain the highest possible quality.
One of my friends also wanted a copy, but wanted a normal cd, at 44.1khz/16bit,
Will the downsampling really make the recording sound bad? or is it just better to record in 44.1 in the first place?
Will recording in 44.1, and recording in 192 and then down sampling to 44.1, sound the same? |
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| luizmenezesjr |
Record your tapes using 48kHz/24bits...
It's a very good quality because the higher frequency that can be recorded is: 24.000 Hz (48kHz divide by 2), and humans can SOMETIMES hear 24kHz frequencies.
Is you record with 192kHz, you can keep your 96.000 Hz super high frequency, but we CAN'T hear it!, and I think your musics don't have any instrument that are using such high frequency.
(sorry about my English) |
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| Derivative |
further to the issues regarding vinyl. please take into account that the accuracy of the sound reproduced is variable and depends on many factors, not least of which include:
1) record wear (how many times the record has been played)
2) dust/lint on the surface of the vinyl
3) the frequency response of the stylus being used
4) stylus wear
the tracking weight of the stylus and the shape of the needle also influence record wear. a badly worn record sounds noticeably inferior. dust and lint on the surface of the record produce pops and clicks on playback and whilst some people like this characteristic of vinyl its not conductive to accurately representing the sound of the master recording. additionally, lint on the surface of the vinyl can effect tracking and if a stylus doesnt track properly in the groove you can introduce quite severe record wear since the needle exerts massive pressure on the groove if not properly aligned (this again also depends on the tonearm configuration and the shape of the stylus).
record wear is also downward exponential in a sense. the first few plays are were the greatest amount of wear occurs. after a hundred or so plays subsequent degradation is not noticeable although by that point you will probably have new records and will be rinsing those instead.
all told cd is generally a more reliable medium for retaining quality of the original disk recording because it does not experience wear through play and the frequency response of a laser lens is generally cannot generally be compromised in the same way in which a stylus wears over time. |
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| Derivative |
| quote: | It's a very good quality because the higher frequency that can be recorded is: 24.000 Hz (48kHz divide by 2), and humans can SOMETIMES hear 24kHz frequencies.
Is you record with 192kHz, you can keep your 96.000 Hz super high frequency, but we CAN'T hear it!, and I think your musics don't have any instrument that are using such high frequency. |
24,000 hz is largely inaudible. you would have to play the signal at fairly high amplitude before you become aware that it is there and you typically notice high frequency sound at high amplitude because it devastates your ears. for all intents and purposes there is very little noticeable difference between a 48,000hz recording and a 44,100hz recording. dj thy mentioned something about 48,000hz recordings before and it would be cool if he could pop in and reiterate some of it since i forgot what it was. but it was informative.
with a 96,000hz recording and nyquest theorum the highest reproducible frequency is 48,000hz which is far and away above the limits of human hearing. and in either case those frequencies about 20,000 hz typically arent driven at very high amplitudes so it becomes very difficult to notice that they are there. i sometimes swear i only notice the difference because i have a bunch of spectrum analysers open and am actively listening for differences in each recording. in club? nobody will give a damn. base graffiti's house always wins will devastate slinky even if its played on a cassette recorder. |
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