128 kbps to 96 kbps MP3 - big difference?

[joshua4]

I'm hosting a bunch of MP3s on my website and they're taking up a lot of space. I'm using GoldWave and found I can cut the space of each file if I convert it to a lower kbps.

Most of them are
Layer-3 ACM, 44100 Hz, 128 kbps, joint stereo

The file size is reduced by half converting to
Layer-3 ACM, 44100 Hz, 96 kbps, joint stereo

How much quality is lost by doing that? Is it that noticeable? I've listened to a file before and after the conversion but couldn't make out a huge difference.

[guns1inger]

If it is mostly speech and little else, probably not.
If it is music, and the original was a reasonable quality, then yes, most people will notice the difference.
If the quality of the original was low then the difference may well be small.

Personally, I would not encode anything but spoken word at 96 or lower

[joshua4]

What about converting from joint stereo to stereo, is that a big difference in quality? I reduced a file's size by 25% doing that. Other ideas are welcome.

[TJohns]

Filesize is purely dependant on bitrate - in a stereo file the bitrate is pretty much split evenly between left & right tracks (so both get slightly lower quality). In a joint stereo file, one track is encoded with the majority of the bitrate (giving better quality) and the other track is encoded as the DIFFERENCE between it and the first track. Since with stereo both tracks tend to be similar, the difference will generally be small, and so require a lower bitrate to encode.

As for quality loss, a recent listening test report here in an Aussie mag indicated the MOST people can tell the difference between an original CD playback even when compared to a so-called "lossless" encode when played back thru quality (i.e. AU$20,000) audio gear.

[AlanHK]

What about converting from joint stereo to stereo, is that a big difference in quality? I reduced a file's size by 25% doing that. Other ideas are welcome.

You need to say what kind of audio.

String quartet? Thrash metal? Religious sermons?
A lot of podcasts are 48k.

Mono would be even lower than stereo.
VBR is more efficient than CBR.
Also some encoders are better than others; give higher quality for the same bitrate.

[AlanHK]

As for quality loss, a recent listening test report here in an Aussie mag indicated the MOST people can tell the difference between an original CD playback even when compared to a so-called "lossless" encode when played back thru quality (i.e. AU$20,000) audio gear.

"Lossless" is not "so called"; it REALLY is lossless. If you imagine you can hear a difference, either your decoder is broken, or you're just wrong.

Those magazines love to do tests that "prove" you get better sound from gold cables and such expensive accessories. When it comes to digital, identical is identical. Put in "11001001001010", get out "11001001001010".

[jman98]

I personally consider 128 Kbps MP3 to be the absolute acceptable minimum bitrate for music. I'm not saying it's ideal, but if it's below that, I don't want to hear it. I worked with a guy once who insisted that 224 Kbps was the lowest "listenable" bit rate for music. I think there's a big difference between 96 Kbps and 128, yes. Quality is totally subjective, but just because 96 Kbps sounds OK to you, that doesn't mean that it will to others.

I totally agree with AlanHK. I know of a US company that apparently does big business in selling accessories that cost thousands of dollars for turntables. Vinyl LPs (yes, they are actually still being made) typically start at just under $30 US for new ones and you add multi-thousands of dollars in a turntable and gizmos for it and there's a whole industry dependent on stupid people who believe that "vinyl is better". So I have no problem believing that some test "proved" that lossless is inferior to the original recording, although it cannot be. I recently read about another test that reported that 320 Kbps MP3 was consistently considered to be better sounding than the original recording in a test. Logically that cannot be so, but that says a lot about human hearing and how trustworthy it is.

[jagabo]

Most of them are
Layer-3 ACM, 44100 Hz, 128 kbps, joint stereo

The file size is reduced by half converting to
Layer-3 ACM, 44100 Hz, 96 kbps, joint stereo

That should only decrease the file size by 25 percent. If your 96 kbps file is half the size of the 128 kbps file something is wrong with one of them.

[ricardouk]

Since the new flash player supports aac why dont you convert to 96kbps aac or even less and resample to 22050? you'll save 30% just by resampling and since AAC is more efficient using 96aac/22050 might not be that bad ,unless youre selling your music online.

[MOVIEGEEK]

If the files are speech then I would use mono@64kbps/22KHz,if the files are stereo music then I wouldn't go lower than 128kbps.Another codec that produces good results at low bitrates is WMA9,AAC also sounds good at low bitrates.

[yoda313]

In addition to what moviegeek suggested I'd also recommend wma at 64kpbs for decent audio at really small sizes (that is what I had encoded to back when all I had was a sd card mp3 player and limited to a 512mb card). Now that I use a 30gb mp3 player I use either wma max at 192 or mp3 at 320 depending on my mood at the time of ripping.

If it is still available mp3pro is equivalent to wma at 64kps (essentially half of a 128kpbs file with little noticeable loss in quality).

[joshua4]

The files are music, music, music.

Thanks everyone for the input. It sounds like I'm screwed and there is no acceptable way to decrease the file size without sacrificing noticeable quality. The users listening to the files are big fans. If perfectionists like you are any indication I've no doubt people would get upset.

I think I'm going to have a low quality version to use for our flash player on the site and host the high quality versions for download off site at like Putfile.

[ricardouk]

...our flash player on the site ...

May i suggest a different aproach? since you are using a flash player to play your files why not convert to aac, its widely reported that it has better compression, you could also host your aac/mp3 files on www.blip.tv it wont reconvert your files, it will give you a direct link to the file, all you have to do is change the links, blip.tv has unlimited storage and has been around for ages so i doubt it will shut down in the near future.

i dont know which flash player you're using but if you use this one:
http://www.jeroenwijering.com/?item=JW_FLV_Media_Player

you can specify a download button in the player, your visitors will download the file from blip.tv, this way you can still have your HQ music files hosted and also have the possibility of a download button for each file.