Has AC3 encoding different with MP3 encoding ?

[Sherlock Holmes]

Hi guys
As you know , I am a movie dubber in Iran
There is a huge problem for me. When I encode my voices to MP3 , it plays very very nice like a bitch. :-)

But when I encode them to AC3 , I see they plays with problem.
The voices will be very low and it goes up and and down very quickly.
For example when the voice of dubber is loud , the sound you hear goes very low. And when the voice of dubber is low , you can hear ok.
I mean being low or high , depends to the voice of dubber. If it is loud , you hear low. But if it is low , you hear good.

What is the matter ha ?

I think Derrow can help me.

[DSPguru]

Greetings Sherlock,
if you only encode voice, drop AC3/MP3/etc'... - use a Vocoder !

[LigH]

What do you mean with "low" and "high"? I guess the voice does not change the pitch (it doesn't sound like Mickey Mouse now and like the Devil then?) - If you mean that a loud voice is compressed in its volume, then you should look at your dynamic compression settings - for encoding as well as for decoding. I would guess that you are either using heavy dynamic compression for playback or a wrong dynamic dompression detection for encoding. For MP3 there is currently no player which cares about the internal factors, its playback is always linear - but for AC3, some players can use dynamic compression (there are, for example, DirectShow filters available). And "heavy" dynamic compression amplifies weak and lowers loud scenes twice as much as the encoder suggests in the AC3 stream.

[MaTTeR]

I've never really had any problems encoding vocals using a bitrate around 64-80. Anything lower than that and I hear pre-echo artifacts.

Happy Holidays guys!

EDIT- I'm speaking of MP3 LAME encoding of course.

[Sherlock Holmes]

@DSPguru
Tnx but give me a link to download it. And are you sure that I can success in this case with like the software you told me ?

@LigH
Yes it compresses. So how can I set the dunamic compression ?
I am using SonicFoundrySoftEncode