KVR Audio

Cabinfever · Post by **Cabinfever** » Mon May 16, 2005 3:55 am

i'm a bit confused about converting to MP3. i need to heavily crunch a few files...

i'm trying to choose between 22KHz at 128K or 44KHz at 64K.

can someone tell me which is better and why ?

donbrad3 · Post by **donbrad3** » Mon May 16, 2005 4:08 am

oooo....mmmm....neither? If I had to choose between the two, I would say the 22kHz @ 128Kbps (which means Kilobytes per second). The higher the bitrate for an mp3, the less compression, therefore the less 'loss' you get from the original source file. When you compress below 128Kbps, all sorts of audio artifacts start show up in the sound (moreso than 128). If you are able to, I would suggest 44Khz @ 128Kbps.....that way you are still keeping a CD quality sample rate, even if the mp3 audio quality is a bit 'lossy'. if not, then 22kHz should be ok for what you need since our own ears only hear a frequncy response from 15Hz-25kHz.............Get all that?

Warmonger · Post by **Warmonger** » Mon May 16, 2005 4:12 am

I'd go with mono instead of stereo, if you haven't already done that (though you probably have).

Is MP3 necessary? There are much better options for low bitrate encoding, IMO.

Churchy · Post by **Churchy** » Mon May 16, 2005 4:17 am

donbrad3 wrote: if not, then 22kHz should be ok for what you need since our own ears only hear a frequncy response from 15Hz-25kHz.............

whoa 25kHz, i doubt most babies could hear that high

but don't forget that a 22kHz sample rate cannot produce frequencies higher than 11kHz ....

cold c · Post by **cold c** » Mon May 16, 2005 4:27 am

donbrad3 wrote: 128Kbps (which means Kilobytes per second).

Just to clarify, it actually means kilobits per second.

Warmonger · Post by **Warmonger** » Mon May 16, 2005 4:47 am

Just to emphasize, when I say there are better options, that even includes WMA (which virtually anyone can play). To my ears, Vorbis is better at 64kbps than WMA, but both are at least as good as 96kbps MP3.

cron · Post by **cron** » Mon May 16, 2005 4:57 am

I know this is hardly a useful question, but what's brought the necessity of this choice about?

Peel · Post by **Peel** » Mon May 16, 2005 4:59 am

The 128k MP3 will have better sound quality. You realize that it will also be twice the file size as the 64k MP3, right? Bitrate is bitrate; encode from the highest-quality file you have (that your MP3 encoder supports) and choose whatever bitrate best fits your quality/filesize requirements.

cron · Post by **cron** » Mon May 16, 2005 5:03 am

Actually, are you thinking that the 128k file will be the same size as the 64k one if you halve the sample rate?

Afraid not (if that's what you were hoping), it'll still be twice as big. Bitrate is just a measurement of bits per second. Nothing changes that.

Oh, and this wouldn't be a cron post in an mp3 thread if I didn't remind you to use joint stereo.

edit: Peel beat me to it.

Cabinfever · Post by **Cabinfever** » Mon May 16, 2005 6:44 am

thanks for all the replies, much appreciated, but i'm still a bit unsure about the exact relationship between these two values. the 44KHz/22KHz choice is for the 'absolute' frequency range is it ? while the 128K/64K choice only relates to the degree of compression to MP3 format ?

(cron: this is for an online job for a client and that's what they suggested to me as options. normally i just deliver wav files...)

Churchy · Post by **Churchy** » Mon May 16, 2005 6:59 am

if you start with 22kHz and encode at 64kbps, there will be less "loss" because there's not that much to lose (since you started with only 22kHz)

if you use 44khz and encode at 64kbps, there is more that will be 'lost' (those high frequencies are the first to get raped by mp3) and you will get more weird artifacts

maybe best to test both ways so you can hear the difference

Warmonger · Post by **Warmonger** » Mon May 16, 2005 7:04 am

CD quality wave files (44.1khz, 16 bit, stereo) take up roughly 1400 kbps. If you compress those to 128 kbps, you're acheiving about an 11:1 compression ratio.

If instead of 44.1khz, your sample is 22.05khz, the original bandwidth was about 700 kbps. Compress that to 128 kbps, and the compression ratio is more like 6:1.

The final file size will be the same for both of the compressed files. More data was removed from the 44.1khz file to make it fit in the same space, but the 22.05 source had less data in the first place.

Warmonger · Post by **Warmonger** » Mon May 16, 2005 7:06 am

I'm really not that slow. I just had another paragraph typed up, and decided to cut it before I posted.

Cabinfever · Post by **Cabinfever** » Mon May 16, 2005 8:24 am

thanks

i think i understand now.

cron · Post by **cron** » Mon May 16, 2005 9:16 am

I'd suggest speaking to the client and making sure he/she understands that a 128kb/s 22kHz file will still be double the size of a 64kb/s 44kHz file. If the client doesn't get it, I'd say go for the 64kb/s 44kHz option. People will probably laugh if they download a 128kb/s file at 22 kHz. You'll lose everything under 10.5 kHz at 22kHz, and most (properly encoded) mp3 files at 128 will go up to about 16.5 kHz before lowpassing the audio. It'd just be a total waste of people's bandwidth if you were to do it that way.

Assuming the source is 44kHz that is. No point at encoding it higher than the source sample rate at any setting.

Better sample rate or bit rate ?