AC3 Editing Questions

[Xesdeeni]

1. If I want to edit AC3 audio along with MPEG-2 video (assume only cuts), do I have to completely decode it?

2. If I decode a 5.1 AC3 stream with BeSweet (because I need to do fades), will I get three stereo WAV files?

3. If I start with the 6 channels generated above, and re-encode to AC3 after editing using BeSweet:

a. Can I generate 5.1 AC3?
b. Will there be an unreasonable loss in quality?
c. Can I be sure the channels will map to the correct places (i.e. the .1 goes to the channels that feeds the bass)?

Xesdeeni

[E-Male]

1. If I want to edit AC3 audio along with MPEG-2 video (assume only cuts), do I have to completely decode it?

No, there are vob-cutters


2. If I decode a 5.1 AC3 stream with BeSweet (because I need to do fades), will I get three stereo WAV files?

No, you will get 6 mono waves


3. If I start with the 6 channels generated above, and re-encode to AC3 after editing using BeSweet:
a. Can I generate 5.1 AC3?

Yes


b. Will there be an unreasonable loss in quality?

Technically there is a loss, but i don´t think you´ll notice it (but it depends on what you do with the waves)


c. Can I be sure the channels will map to the correct places (i.e. the .1 goes to the channels that feeds the bass)?

If you do it right, all channels should be in the right place


CU
E-Male

[Xesdeeni]

Thanks for the quick answers! One clarification, on 3b, I was probably asking more about BeSweet's decode/re-encode quality.

Xesdeeni

[KpeX]

I was probably asking more about BeSweet's decode/re-encode quality.

As E-Male said, with any transcode there's always some theoretical quality loss, but IMHO besweet's ac3 encoding quality is excellent. It is not uncommon to transcode AC3 to a lower bitrate with besweet to save space for a rip, and this results in quite good quality.