Connect the DVD player to your computer. Using the A/V RCA 1/8-inch cable, connect the red, white and yellow RCA end of the cable to the RCA outputs on your DVD player. Then connect the 1/8-inch side of the cable to the audio input on your computer.
Create a new project in your audio editing program, such as Garageband or Protools. Save the file to your desktop and give it a name that matches the song you are capturing from the DVD.
Record music you want from the DVD. On the DVD player, advance the DVD to the music part you wish to record. Press "Record" in the audio editing program. On the DVD player, press "Play." Let the program record the DVD audio until your song has finished, then press "Stop Record" in the audio editing program.
Export your song from the audio editing program. In the program's export menu, select the option labeled "send to media player." Name the file using the name of the song you captured and then save the file. You now can open the file in your media player program.