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Topic: CBR at high bit rates (Read 5899 times) previous topic - next topic
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CBR at high bit rates

Since I have gotten into DJing I have read that some clubs still have equipment that cannot read VBR files. Therefore, for my House music only I am going to encode to CBR. I need to make sure my files are abe to be played no matter where I'm at. Compatability is important for my House music.

My question: is there any real audio quality difference between LAME 3.98 and Fraunhofer IIS at CBR 256kbps? Is there any noticeable audio quality difference between either at 256 CBR and LAME -V2? Or is one simply giving up the smaller file size -V2 offers for the same audio quality?

Most of what I have read here says once the kbps reaches the 256 levels, its all pretty transparent no matter the modern encoder or format (LAME 3.98 MP3, Fraunhofer IIs MP3, Apple AAC, Ogg Vorbis). Introducing VBR simply maintains that audio quality while shrinking the file size through efficient kbps decision making.

Is any of that incorrect? Should I be using 320 kbs for CBR? I am surprised how many electronic music stores, especially stores that cater to DJs,  offer MP3 at 320 kbps and not 256. Is it not just a waste of space? Some even recommend CBR 192 kbps as the threshold for transparency but there seems to be much debate on that - which is why I went up to 256 kbps where there seems to be no debate about transparency.

Remember, its not just MY ears I'm concerned with, but the ears of others as well since I will be DJing.

CBR at high bit rates

Reply #1 –
A bit of History:

In the early nineties, audio engineers were worried about how to transmit audio (and video) data at a reasonable quality, within a constrained bandwidth. At the time of divising MP3, the goal was to get a "standard" quality through a bandwidth of 128kbps (which was what a dual-ISDN connection could transmit).
Standard, here, ended meaning, the audible bandwidth of FM radio, without the interferences of the latter.
But since that didn't sound too promising, it started to be billed as "CD audio quality". Sure, an mp3 at 128kbps plays back at a sampling rate of 44Khz, like a CD audio, but the audio bandwidth is not the same .

In the end of the nineties, when the format got known, and began to be mass transmitted over the Internet, people got more interest about higher quality, and more "like the CD" than that of the 128kbps file.

192Kbps got billed then as the "CD audio quality". It increased the bandwidth from those 16Khz into 19 or 20Khz, depending on the implementation (some worse implementations actually kept the whole bandwidth), and since the fraunhofer encoder, by default, encoded to simple stereo with this setting, joint stereo got to be seen as "the lesser quality" stereo. (This, and of course, the bad intensity stereo of MP2, and the bad implementation of the older Xing encoder.
Edit: Also, as noted by /mnt, one version of the fastenc encoder had a joint stereo bug. Note, it had anotherjoint stereo bug on a newer version)

Fast forward to one or two years ago, when the DRM scheme started to be depicted, a higher bitrate mp3 (or mp4, in case of iTunes) got billed as "the next best thing", as in "more value for the money".
Bandwidth is in no way as limited as it used to be 10 or 15 years ago, and the Hard drive space has increased even faster. As such, using now a higher bitrate is not as detrimental as it could have been then (except in the smaller, or flash-only "mp3" players. Yet, note that the first mp3 player, the Rio, had 32MB of flash. So yes, that was just 8 Mp3, not even one CD at 128kbps).


Now, the strictly quality point of view:

The mp3 format, as great as it has shown to be, has a lot of deficiencies. Some get hidden, or almost removed with more bitrate, others not. In some special cases, the highest bitrate is not enough to faithfully encode everything.

It is usually difficult to test the quality of the highest bitrates, precisely because the fautly samples have either inherent format flaws (which don't go away with more bitrate), or are "killer samples", getting on the knees of the encoder.

Variable Bitrate encoding allows the control, by the encoder, of the bitrate distribution in order to get a constant quality. This translates into flexibility that allows to have the highest bitrate in some cases, and lower it in some others, attaining a similar file size.


As such, -V 2 in LAME is not comparable to 192, 256 or 320kbps CBR. It can use 320kbps in some cases, but the 320kbps encoding has more bits than the -V 2 to spare, so it can increase the quality (even if it is not perceptible).



Now, as to your specific question:

both, 256 and 320kbps should be good for you. None of those encodes should give you problems on dj hardware. As for the best of both, you should judge. How much space do you want to use (will be using MP3 Cd's? flash memory? portable USB-HD?), and get the highest one that fits.
This suggestion is mostly, for your public, and for the event that you record your session and encode it back to mp3. (I am fed up of listening to 192 and 256kbps mp3 mixes, where mp3's as low as 128kbps have been used as a source).


Thanks for your reading.

[Edit: spelling and clarifications]

CBR at high bit rates

Reply #2 –
I would personaly use 256 kbps, for high CBR use. Since 320 CBR has to have the bit reservoir disabled, which would still will sound better then 256, but IMO would only be a minor improvement and not worth the extra 64kbps.

Quote
' date='Oct 29 2008, 20:34' post='596351']

192Kbps got billed then as the "CD audio quality". It increased the bandwidth from those 16Khz into 19 or 20Khz, depending on the implementation (some worse implementations actually kept the whole bandwidth), and since the fraunhofer encoder, by default, encoded to simple stereo with this setting, joint stereo got to be seen as "the lesser quality" stereo. (This, and of course, the bad intensity stereo of MP2, and the bad implementation of the older Xing encoder).


Am sure it was a buggy version of Fhg's fastenc mp3 encoder, that gave Joint Stereo a bad name. Since Xing was so imfamus for being a poor encoder, everyone seems to scrapegoat it for giving a Joint Stereo a bad rep.
"I never thought I'd see this much candy in one mission!"

CBR at high bit rates

Reply #3 –
Storage space is not too much of a concern as I can transport music on CDs at about $0.25 a CD, or a 4GB flash drive, or my 250 GB portable hard drive or 120 GB iPod. That being said, some might say "just use 320 and forget about it", but if 320 produces no perceived improvement over 256 why bother? I would use 192 but I still "perceive" artifacts at 192 CBR occassionaly.

I never perceive artifacts with -V0 and have yet to do so with CBR 256. Bu that is just my ears - not everyone's ears listeing to my music.

CBR at high bit rates

Reply #4 –
You mean that while djing, on a (mostly sure) noisy environment, you hear artifacts?

CBR at high bit rates

Reply #5 –
Quote from: kwanbis on
You mean that while djing, on a (mostly sure) noisy environment, you hear artifacts?

Let's hope that he means careful listening in a proper environment. Either way I would like to see ABX results to back up his statement.

CBR at high bit rates

Reply #6 –
Quote from: /mnt on
Am sure it was a buggy version of Fhg's fastenc mp3 encoder, that gave Joint Stereo a bad name.

I mentioned Xing, because the first versions used intensity stereo instead of mid side stereo. I looked a couple of days ago, and i still have some of those encodes, which I encoded from some LP's.

But you're right, the pirated version of the fastenc encoder did indeed have another joint stereo bug. There was another version with a joint stereo bug.


Quote from: pdq on
Let's hope that he means careful listening in a proper environment. Either way I would like to see ABX results to back up his statement.


It is not the same to be able to hear a problem with a specific file at a certain bitrate, than claim that it is a common problem. He did imply the former (as implied by the use of "occasionally" word).
Not even 320kbps is completely free of that.

Edit: Added the correct link. The link i pointed is about a newer build, which also had a problem.

CBR at high bit rates

Reply #7 –
LOL. No.....in a quiet environment with high quality headphones I can sometimes still hear the muddy bass and swoosh of delay on the cymbal at 192 CBR. Occasionally, not always. More often at 128 CBR since I've trained my ear to listen for it.

My concern was to not have the muddy bass drum sound in a club DJing in front of people. Could they hear it at 192 CBR? I don't know. I just know the music needs to sound lively.

But that was not my question. My question was.....I am thrilled with the sound at -V2 and -V0 and was wondering if CBR 256 is about the same with either LAME or Fraunhofer albeit at a higher bit rate than -V2 and if not, should I use 320?

CBR at high bit rates

Reply #8 –
Using 320Kbps CBR for MP3 is only going to take up 25% more space than using 256Kbps. If you personally feel happier to use 320Kbps then go ahead and use it. There will always be rare instances where 320Kbps will outperform 256Kbps, so it makes sense to use it if the highest possible level of transparency at all times is a requirement.

It's a shame that the manufacturers of the equipment in question are too incompetent to support VBR when it's been a requirement for standards compliancy since at least 1993, but if you're forced to use CBR then you may as well use it to the full. If you don't then you're just throwing away a bitrate than even fairly modest VBR settings have access to.

Cheers, Slipstreem. 

CBR at high bit rates

Reply #9 –
Quote from: ezra2323 on
My question: is there any real audio quality difference between LAME 3.98 and Fraunhofer IIS at CBR 256kbps? Is there any noticeable audio quality difference between either at 256 CBR and LAME -V2? Or is one simply giving up the smaller file size -V2 offers for the same audio quality?

just a bit of technical info... FHG for some reason is afraid of encoding into sfb21 (>16kHz) and even at 320kbs it often has just little content in this frequency range. It is easily noticable for someone with bat ears because the energy in this frequency range is encoded in "bursts" (possible ringing-like artifact).

I'd avoid FHG for anything over 160kbps because of this.

CBR at high bit rates

Reply #10 –
Also FHG is not so confident with Joint Stereo, at higher bitrates (>224) FHG encoders use Stereo instead of JS.
"I never thought I'd see this much candy in one mission!"
 

CBR at high bit rates

Reply #11 –
Quote from: /mnt on
Also FHG is not so confident with Joint Stereo, at higher bitrates (>224) FHG encoders use Stereo instead of JS.

The new surround encoder uses JS all the time, for the encoder in Cool Edit you can select channel coding. Just some old/simple implementations had that "bug".