high rez sound track?

Keep the AC3. AC3 = Dolby Digital 5.1

Why AC3? LPCM (Linear PCM) is an uncompressed audio format. It can have up to 8 channels of audio at 48khz or 96khz sampling frequency and 16, 20 or 24 bits per sample. It has a maximum bitrate of a huge 6.144 MB/s. Dolby Digital is a lossy format.

the dvd I mention actually is a music video, with 48khz16...I believe 2 channels. So which one should I keep? sorry Im new to this and have no ideal which one will produce better sound....

I know little about backing up DVD's but I would always lean toward the highest fidelity (which usually means uncompressed or lossless compression, neither of which is AC3). LPCM is completely uncompressed and can handle your 16/48 audio perfectly. I may be missing something here, but why choose the compressed option?

thank you everybody for chipping in. Obviously I was so clueless regarding this LPCM... that why I posted this question. Usually for movie, dd and dts would do fine, dont know why people have to add in the PCM.... I guess for music video, I will keep the LPCM instead...