.WAV Compression

[Berne]

Hi All,
I recently took a course and recorded the lectures. There are 25 .WAV files with a total of around 1GB of voice data.

What is the best way to compress so many .wav files into one large file...please relate best option for compression.
I do have the Audacity programe?

What is the best FREE mode to offer the compressed file for download to future students of the course? Modem speed will of course vary.

Any reply should also state if it would be best to compress total files into perhaps three 300MB files or would one file be just as feasible?

All good advice welcome,

Berne

 

[IGemini]

Best would be some combination of:

- Using Audacity or dbPoweramp to reencode the WAV files as MP3.
- Compressing the files. .zip format is everywhere, 7zip would probably compress better.

 

[iCyborg]

What's in the wav? If it's standard CD audio (i.e. LPCM format), then I agree with the above: reencode it into something a lot smaller, there's little reason to keep what is mostly speech in CD quality, heck, there are some formats like AMR which are pretty decent at ~10kbps or so for this purpose.

 

[CycloWizard]

It's usually illegal to record lectures without the permission of the instructor, since their lecture material is essentially what they're selling. You might want to consider this if you're planning on selling these or putting them up for download, as most universities will watch for this sort of thing.

 

[Murloc]

audacity
use 128kpbs mp3 or even less with aac+.
mp3 is best for most people.
Even lower bitrate may work, but it depends on the quality of recording and how the speaking is.

 

[Berne]

Hi,
The resulting file will rest with the tutor, they can use file for future students as they see fit, thank you for the headsup on that.

So, I can compress to MP3 + 7zip thank you. Yes its voice audio only, but can you let me know if I should try to compress the full amount of current .wav files ( 14 @ 1GB ) into 'ONE' MP3 or space into 3 or 4 MP3 files using Audacity?

Berne

 

[IGemini]

It would probably be much more convenient to just encode the files as they are and date label each one. Going from wav to mp3 should shrink the files by more than 1/4 and you can compress it to one or a few zip files.

 

[Murloc]

each lesson should be a file, otherwise it's difficult to find the right spot.

 

[Berne]

Hi,

Many thanks,

Berne

 

[spikespiegal]

Why would you gain more compression by ZIP'ing it?

 

[IGemini]

You wouldn't necessarily. I suggested it for the convenience having one file to download instead of several.

 

[Throckmorton]

You can compress to 64kbps (MONO not stereo) mp3 and quality will be great. A lot of lectures and podcasts come in that bitrate or even 32kbps.

 

[Chapbass]

You can compress to 64kbps (MONO not stereo) mp3 and quality will be great. A lot of lectures and podcasts come in that bitrate or even 32kbps.

This! just someone talking is cake to encode since it doesn't really have the wide frequency range of music (okay, some music). If it was encoded with something like a handheld mic, even more reason to encode at a low level as the source material isnt super pristine (as opposed ot if he was speaking into a condenser mic).

 

[Cogman]

Can I just suggest using AAC instead of an MP3 encoder? The quality is usually significantly better for much lower bitrates, a good AAC encoder at 64bit/s music can sound as good as a decent 128bit/s MP3 stream.

As has been mentioned, talking is pretty easy to encode as distortions really don't detract from what you are listening to (That and the ranges are much, much lower than music).

I could easily see 32 or even 16 bps with AAC being plenty for a pretty good sounding audio.

neroaac is free to use. If you must use MP3, then use LAME as your encoder.

 

[silverpig]

One suggestion that I would make to do in addition to the mp3/aac/whatever is to also put them into audiobook format. To do this, use iTunes to encode each file to aac (.m4a extension), and then just rename the files to .m4b. This way the user will be able to bookmark the lecture and pick up where they left off, and will also be able to increase/decrease the reading speed. It's very simple to do.

 

[Murloc]

You can compress to 64kbps (MONO not stereo) mp3 and quality will be great. A lot of lectures and podcasts come in that bitrate or even 32kbps.

that makes sense. Stereo is useless since it was registered from a single crappy mic already.