I encoded a 5.1 wav audio file to 5.1 ac3. The ouput seems good on pc but when played on a set top player, sounds fluctuates to highs and lows. Each song starts at normal level but when it reaches higher db, the sound level decreases. This is repeated every time there is a db increase or decrease. It sounds horrible to the ears. I encoded the file using the default settings of surcode. I was wondering if this has to do with the dynamic range compression. If I set dynamic compression to none, would I solved the problem? Or is it an issue of other settings? Any help would be much appreciated.

There's some really good info in the stickies, particularly the one on ac3. I'm not expert with surcode, but while waiting for one to answer your question, it definitely does sound like a compression prob., with the way your stand-alone is reading the settings anyway, so try an encode without & burn to a rewritable.

I read the detailed post of SomeJoe and that is why I came to this conclusion. In the meantime, I re-encoded the file. I have to burn it and try it. Will post the result later.

Btw is there a free software to measure RMS for dial norm?

this isn't intended for dialnorm, however i've found that ReplayGain scans come out remarkably close to just the right level for a -27dB dialnorm (and you can set mix level to 89dB as well, though i'm not sure this makes a difference). so you could use a little free proggy called WaveGain to pre-process your wav file, then feed that to surcode. although i don't know if it handles 6ch wavs. if it doesn't try use Foobar2000 to do it - it's also got a replaygain scanner. one thing you might consider doing is turn off DRC on your standalone player. turn it back on if you need it (like you're getting dinner and can't hear the TV over the cooking noises in the quiet bits), but a decent sized stereo is MUCH more impressive with DRC turned off and the volume turned high. try turn it up so that dialogue in the movie is the level of a person talking normally in the room. then everything else should sound right.

Audacity will accept a 5.1 wave file as an input file but I believe when you go to save it after editing you can only get a stereo wave file as the output.

@mic I encoded the file using lower dial norm under music and effects but the result is still the same. Any more ideas? @bobcat Thanks for your suggestion but after the work it took me to do it 6 channel, I will certainly not go back to 2 channel.

Thinking.... ...Thinking....... ......Guessing...... :confused: I have been and will keep thinking about this... Brainstorming with the keyboard, if you had the prob with a wav file(s) on your PC I'd probably jump at either poorly implemented dynamic compression, or wrong compression settings. My portable has menu controls for the level or use of compression, but I hadn't remembered that till just now as I've never set it. The other thing that occurs, but is more a random thought that might inspire an idea, I had a prob once with a PC -- turned out the speakers (which were remans) were wired with different polarity. Meant the right and left were out of phase and canceled each other out at some freq... Not that your speakers are bad, but could there be something going on with phase/phase delay? I'll keep thinking... :(

Thanks for your help and thinking mic. The wav file is fine. The problem is after it is encoded. What do you mean with "dynamic compression"? If you are refering to DRC while encoding the ac3 file, I used no DRC. As regards the speakers, I checked them and they are ok. Still original DVDs don't have this problem. It's just with the file I encoded. I strongly believe that I am doing something wrong with the settings of encoding. I am not well versed in the field so I don't know what else I can try. I read losts of posts and websites but still can't figure out the correct settings I should use. Btw this is my first 6 channel ac3. I previously encoded 2 channel ac3 and did not have this problem.

mic, I have an idea now, thanks to Tebasuna. I was reading a post where Tebasuna stated that wav and ac3 files have different channel order. I didn't know this so now I'm wondering if this is the case. Is there a software to verify this and that can swap channels for the ac3 file? Tebasuna, If you are reading this, your help would be much appreciated.