Be Excellent To Each Other

Hello, I recently recorded massive chunks of TranceFM as single huge MP3 files. We're talking 7-10 hours at a time, weighing in with file sizes of 700MB to over 1GB.

Unfortunately, my car stereo chucks a bit of a mental with such huge single files, it will play them fine (after thinking about it for a bit), but once the track gets past around 95 minutes, it won't resume properly, instead it has an extra long think, and then just goes to the next track, which means I can only listen to the first 95 minutes of any recording.

(Curiously it'll play past 95 minutes quite happily, with the display reading 105 minutes or 120 minutes or whatever, it's only when I stop the car and come back to it (i.e. stereo powers down and powers up) that it throws a strop and goes to the next track.)

As such, what I'm after is a bit of software that will open up a massive MP3 file, allow me to chop it up into small bits (around the 90 minute mark each, so about 100MB each), and then save those bits back out as individual MP3 files that I can copy onto my USB stick for the car.

I've tried Audacity but it takes AAAGGGGEEEESSS to open up the file, and then it requires a re-export rather than just simply saving out the new chunk.

I've tried a couple of other bits of software, and they simply crash out, presumably 'cause the files are so big.

I could persevere with Audacity but it'll take a long time and on top of that, the fact it wants to re-export the MP3 rather than just re-save what's already there will, I presume, lead to a drop in quality.

Any suggestions?

Cheers!

I might be talking out of my arse, but I think that the reason that Audacity has to re-export the MP3 (rather than just savethe two bits) is that it can't. Because MP3s are compressed, there's information about how the MP3 was intially compressed saved somewhere in the file itself, without that it won't work.

Think of an MP3 as being a Word .doc in a zip file. You can't just cut the zip file in two, and hope you get page 1&2 in the first half, and 3&4 in the second. You have to expand the archive, open up Word, manually separate the pages into two files, then re-compress them into zip files.

Audacity is going through exactly the same process when it loads your MP3. It converts it back to a .wav file, so you can fiddle with it and has to recompress the two halves when you've done.

The Mac version of Quicktime can do this, so I suspect the Windows one can.

Open the mp3 with quicktime and you should be able to select a region, then 'crop to selected region' and save. Then repeat.

Hmmm, this actually seems to work.

http://www.acapsoft.com/det.php?prog=Chop

Requires a bit of manual renaming afterwards, but the chunks of file go seamlessly from one to the next when queued up in Winamp.

Hmmm no that doesn't make sense because it's possible to record an MP3 in real time, so the MP3 recorder has no means of knowing when you're going to start and stop recording, so the file has to be complete at any moment in time. i.e. It's entirely self contained and any chunk thereof has to be self contained as well.

In the form of compression you're talking about (traditional zip files for example), there's already a defined 'end result' to be compressed, so the program involved knows it won't change and it has everything to work with before it starts.

An mpeg video file is binary, hence why you can combine them with the copy DOS command.

But the metadata in the file isn't written until you stop recording. It'll buffer the audio data on disk, then wrap it all up when it's done. Try recording an MP3 in realtime, then killing the recorder process using task manager mid-stream - if there is any MP3 file on the disk at all, it won't be playable.

So how does that Chop program work then?

I....don't know. It really shouldn't.

Right, so the mp3 stuff itself is perfectly choppable, but the metadata sits at one end (the latter end, from testing). So you won't get any of the album/artist etc stuff that comes along with it, except in the last chunk. But then you don't actually give a shit about any of that, because it's a trance radio stream, so I'll shut the fuck up now.

I tend to use mpTrim for this kind of thing.

Hurrah for self contained executables! Fed up of everything wanting to be installed, I am.

That sounds like what happens when politicians get caught with their hand in the cookie jar

Then search for portable versions. I have portable photoshop, frontpage and others. They're tiny too, photoshop is abouit 40mb for CS IIRC

Plus there's no reason a clever chop couldn't duplicate it anyway.