recommendations for MP3 format for long lectures

[tomchook]

Hello,
My department in the university uploads MP3 files of each lecture. It's only audio, and each lecture last for about 100 minutes. Right now, the MP3 is mono, and the avarage size of the file is 70MB. Is there any way to make these audio files smaller in size, and still get a good quality? What would you recommend?

Thanks!

[jagabo]

Try 16 KHz, 16 bit samples, 32 kbps mp3.

[Denizzje]

Do you only play them on your computer? Or do you put them on a music player which only accepts mp3? If you only use them on your computer, you could use better formats like OGG Vorbis or HE-AAC .

[jman98]

I can't agree with jagabo's recommendation because while it will work, if someone needs to upconvert the KHz, say to burn it to CD audio, it will sound like absolute crap. My recommendation would be to leave it 44.1 KHz for CD audio compatibility and drop the bit rate to 96 or even 64 kbps if you must. I cannot personally recommend going below 64 Kbps.

While Denizzje's suggestion has some merit, the problem is that idiot users will have no idea what OGG or AAC are. You'd probably do best to leave them as MP3.

[jagabo]

His files are already at about 96 kbps. What I recommended works pretty well for voice recordings and is roughly equivalent to 128 kbps with 44.1 KHz sampling.

[Midzuki]

However many idiots have already heard .MP4s on their gayPods.
I'd suggest NeroAACenc for producing 64kbps LC-AAC or even 32kbps HE-AAC,
given that the MP3 sources are mono.

[AlanHK]

Use VBR MP3 if you aren't already, gives a bit more quality for the same average bitrate.

If you are starting from a fairly compressed file, any recoding will give you a noticeable quality hit.

But it is a lecturer droning on, not chamber music, so a really low rate may be acceptable.