low volume after conversion with convertxtodvd

[kthan]

I tried to convert XviD to dvd by using convertxtodvd. Since I need to join two AVI files (XviD, 50 min each, 700mb), I used ffmpeggui to convert mp3 audio to AC3 (one file had mp3 and the other file had acs. So, I converted one AVI with mp3). After I finished, I opened virtualdubmod and go to stream list (diable original mp3 audio, and then add new AC3 files). Then, I was able to join two AVI files in VirtualDub by using "append AVI segment" option. I saved it as new AVI file, and used it at "convertxtodvd." After sucessfully converted, I checked it before burining DVD, and found that audio volume is so low (compared to the original). I don't know what's wrong. I converted mp3 to AC3 (192kb bit, 48000, 2 channel). Am I doing wrong somewhere in this procedure? The new AC3 file size is about 90mb. Each AVI file size is 700mb. Combined AVI size was 1.3gb and the mpeg2 file after conversion is 1.38Gb. I chose high quality/slow encoding and with highest priority. Please advise me how to correct it.

[guns1inger]

AC3 generally sounds lower than MP3 because it has a wider dynamic range. That said, it is also played back via a different codec, and there is a good chance that on your PC, this codec has an indpendent volume control that is set lower than normal. This is the usual suspect in mp3 to AC3 conversions, as the butchery of MP3 compression has killed any real dynamic range before the AC3 conversion gets to it.

Do you use FFDShow or AC3filter or similar for playback ?

[Wile_E]

Here is the doom9 guide to AC-3. It shows that properly encoded AC-3 audio should have a peek loudness of only -31db. This gives it a lower average volume level and is why it is not as loud.

http://forum.doom9.org/showthread.php?s=&threadid=56020

[kthan]

I installed both FFDShow and AC3ACM. Since I installed FFDShow later and associated all files to this program at the time of configuration, I guess FFDShow used for playback.

If AC3 file normally produce lower level, is there a way to process normalization (for louder volume) at sound editing program like SoundForge?

Also, one of video file had original AC3 (not converted from MP3). Its volume was just fine when I played original (xvid) before conversion. Only it produced lower level after I joined two files and convert it at convertxtodvd. Do I need to demux AC3 file before I convert to MPEG2? Or, would it be better to convert AC3 to wav and save it with video file. Then convert it at convertxtodvd?

[guns1inger]

ConvertXtoDVD doesn't re-encode compliant AC3 audio, it uses the original.