When you create a DVD, your disc-burning software combines separate components such as audio, video and subtitles into a single file with a .VOB extension. This process is called multiplexing. If you want to copy a DVD's sound to a CD so that you can listen to a concert DVD on your car's CD player or for other reasons, you have to use software to demultiplex the DVD and produce individual files for each component. Once you have a separate audio file, you can convert it to MP3 format and then burn it to a CD.
DVD Decrypter is a free application that reads raw DVD files, manipulates the files and writes a modified backup copy to your hard drive. One of the manipulation options is to demultiplex the DVD. Download and install DVD Decrypter (link in Resources) and select "IFO Mode" after you run the program so that you can edit individual streams. Enable stream processing, select the DVD stream and choose "Demux" to demultiplex the stream. DVD Decrypter will create an audio file with the DVD's sound in AC3 format. The program will also remove copy protection before it creates the backup copy of the DVD.
DDTool is short for DVD Demuxer Tool. It's a free demultiplexing utility from open source developer Cheekie Moonkie, but it relies on two other free programs – PgcDemux and mplex. Download links to all three programs are provided in the Resources section of this article. Once you've downloaded and installed all three programs, the hardest part is over. DDTool's user interface is simple and intuitive. Create a new job by specifying the input and output file locations, choose the audio stream to demux and run the job. DDTool creates an audio file in VBR MP3 format.
VobEdit is another popular software program that creates modified backup copies of DVDs. The software allows you to demultiplex a DVD, and you can cut and join portions of VOB files together before writing the backup copy to your hard drive. VobEdit is a tiny, self-contained program that you can download and run directly without installing it (link in Resources).
Converting the Audio File
After you have used a demultiplexing utility to create a separate audio stream, you may need to convert the audio file to an MP3 format. Download and install Audacity, an open-source sound editing program (link in Resources). Import the audio file into Audacity and export it as an MP3 file.
Burning the Audio File
Use Windows Media Player to burn the audio file to CD. Select the "Burn" tab, drag and drop the MP3 file to the tab, and then click "Burn" to copy the DVD's sound to a CD.
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