In iTunes, go to your preferences before you start burning. Select "Audio Cd" as the format for the burning. The program will convert it to the appropriate format.
Also, when you import music from CDs, you can choose to import them as MP3s , AIF, Wav, or AAC. If your intention is to later burn a mixed CD in standard audio format, then import your songs as AIF.
Also, when you import music from CDs, you can choose to import them as MP3s , AIF, Wav, or AAC. If your intention is to later burn a mixed CD in standard audio format, then import your songs as AIF.