在linux命令行中将循环轨道嵌入到MP3中？

Question

I'm working on a site for someone where they are inviting their music artists to submit their MP3s for others to pick up and use in their own work - for a price of course. To prevent the artists track from being ripped off by unscrupulous individuals - my plan is to loop a vocal track underneath the 'preview' version and make it useless... and then serve up the clean version to people who have paid for the rights.

I'm using PHP & running on a Linux server - and it seems like a pure PHP solution is not the way to go, with the preference being using an exec() of a command line program to mix the tracks at the point of upload. I need something quick and reliable.

Unfortunately I don't know of any such tools and my searching has come up blank. Can anyone suggest where I might find something? It doesn't have to be free, but it has to be reasonable - and more importantly - simple to work with via PHP.

Answer 1

you can unpack the MP3s to raw (16bit signed) using madplay. then for mixing the two file, read samples and sum them. write the result in a raw file and repack to MP3 using LAME. You can prolly implement that in C or PHP.

Mixing samples is pretty easy : sample = sample1 + sample2; just take care about saturation.

If you don't feel doing that by code, you can use SOX http://sox.sourceforge.net/ it's command line based sound manipulation program. It's supposed to be able to mix sound tracks.