Two mp4 (audio) Questions

I recorded a program for a company I am doing some consulting at. Basically the managers have to listen to it and then they are take tests to ensure they have complied with program.

The orginal plan was to burn the program to a CD in wav and let people play it on their computer but I figured most have mp3 players and it’d be easier for them to take it with them

Anyway I recorded it in .wav form from my computer using my voice. Seeing how huge the files are, I decided to compress it with LAME to mp3.

Then I was reading how if you use the mp4 format you can bookmark it. So you can stop and start. Plus it takes up less room.

So I downloaded the free aac codec from NERO and used Exact Audio Copy to compress the wav into .aac.

My first question is, I read that the files formats


are all the same, and you can use any of them, it doesn’t matter. Is this correct?

Nero by default put in a file extension of .aac

I don’t want to confuse people so I figured I would change the extension to mp4.

Or should I just leave it.

The second question is the bookmarking thing. Is there special players that are needed or anything? If anyone has a decent website they can direct me to I’d appreciate it.

I went to and I see there are plenty of free programs to change mp4 to mp3 so if anyone has a player that won’t play the mp4 they can change it. So that doesn’t seem to be an issue.

I checked and most of the mp3 players can play mp4 so that shouldn’t be an issue.

Anything else you can suggest. These people aren’t the most computer literate.

Hmm… one thing at a time.

  1. If you’re going to be distributing actual physical CDs, burn what are called “mixed-mode CDs”. This means the CD can be played in any regular CD player AND can also hold a .MP3/.MP4 file for computer use. Nero (the burning software, not the codec) can handle this easily, as can many other burning solutions.

  2. Instead of a CD, consider putting the sound file online using Flash. You can break it down into sections/chapters if you want. That might be easier/cheaper than distributing CDs. Or do both if you want. If you don’t want to bother looking for a custom/brandable solution, the filesharing service will let you upload a sound file, password-protect it if you want, and it’ll automatically turn it into an online Flash player.

  3. Yes, .AAC/.MP4/.M4A are all extensions for the same underlying audio codec, Advanced Audio Coding. However, I would stick with MP3 for compatibility’s sake. Do NOT expect your users to be able to convert on their own; if they’re not computer-literate, a lecture is a lecture is a lecture and this mysterious “filetype” thing is black magic. It’s not a big deal on computers but can be for non-iPod digital music players – some of the older or more ghetto ones won’t play .AAC, but everything and their mothers support MP3.

  4. Bookmarking, as far as I know, is player-dependent and not filetype-dependent. For example, iPods will remember how much of a file someone has listened to regardless of whether it’s in MP3, AAC, Audible or some other format as long as the person marks it as an Audiobook in his playlist. Bookmarking is inconsistent across players and platforms right now, so your safest bet is probably to just point out significant points in time (like “Bob speaks about Jane at 01:34. Jane responds at 01:52”).

Thanks I did learn that iPods need to have the mp4 or m4a file changed to m4b in order to have the file go into the audiobook section and to bookmark it.

You’re right about simple. I’ll keep it mp3.

The original plan was for me to burn CD-r and let the people listen to it on their computer or at home on their CD players but quite to my surprise a lot don’t have CD players anymore. So that is when I started thinking elsewise.

Since you feel compatibility may be an issue I’ll keep it as mp3. And anyone who wants a CD version, will just get a wave. The cost is being picked up by the company and CD-r is cheap anyway.

Anyone else have a suggestion I’d appreciate it. It’s my first audio book. LOL