AC3 headers and BeSplit -join

[jweathers7]

Do AC3 files have headers at the very beginning that can adjust the gain or other effects?

I have taken a large AC3 file of a soundtrack, split it apart into clips, adjusted some of the clips via decoding, editing, and reencoding.

In order to make the reencoded clips sound right, I had to:
Surround the track in silence (1280 samples at the beginning and 256 samples at the end)
Invert the WAV forms
Increase the volume by +6 dB


However, after joining these reencoded clips back together with the untouched clips, the resulting large AC3 file sounds like the volume increases around the areas where I reencoded component clips with the exception of one or two of these areas which sound find.

I did an experiment where I left off the +6 dB adjustment before encoding and the result is that the large AC3 file sounds fine now except for the one or two areas that sounded fine with the +6 dB adjustment prior to encoding and joining. These areas now sound too soft.

So is there some header at the beginning of the AC3 file that is adjusting the gain that gets thrown away when an AC3 is appended to another AC3 by the join feature in BeSweet?

[jweathers7]

Hmmm. Well, it seems I will just not use ac3enc for this process after all. There are just too many corrections needed and too many weird results. Instead, I will use Soft Encode as I have now determined that the correcting factors for the silence that it introduces are:

Add 640 samples of silence to the beginning of the track
Add 896 samples of silence to the end of the track
Clip 1536 samples of silence from the start of the encoded result file


When I then used BeSplit to join these reencoded clips with the untouched clips, the result was pure joy on my part because everything sounded correct.