[MEncoder-users] Does MEncoder has issues with AAC audio encoding?

[Grozdan Nikolov]

On Monday 16 July 2007 01:05, Werner Van Belle wrote:
> Hello,
>
> I have been following this treath from afar, but it seems to me that the
> oringal poster his soundcard might be the problem. Many soundcards
> (including soundblaster stuff) also amplify the signal digitally. So, if
> you have a sine wave in, and the sound cards mixer device is set to 100%
> then it will amplify the sine wave above the 32767 value, and thus end up
> with a clipped wave.

I'm not really expert on this one but how do you explain the distortions only 
occurring in surrounding sounds like background music. As I already said in 
my original post, voices and other sounds which come from the center and are 
directed towards the listener are perfectly clear, only surrounding music 
that goes with the movie is distorted and surrounding music is often softer 
than other sounds. There are also other people who have encountered this 
problem and only with AAC audio. MP3 and AC3 are just fine.
I have a SoundBlaster Live! 5.1 and never had any issues with it.

>
> This will of course only happen when the bytes going into the soundcard
> have an amplitude that is sufficiently high. Distortion will not occur if
> only an amplitude of 16384 is sent in the soundcard. Therefor, I suspect
> that the difference between the two decoders/encoders lies not in their
> quality but rather in the output amplitude they achieve.
>
> Practically: if the origanl poster could turn down his PCM and master
> volume to 75% then I suspect no distrotion will occur in any case.

My PCM always stays at 80% as pumping it up to 100% often also distorts music 
I'm listening to (cracking noises, especially with dance music where low bass 
frequencies are very common)

>
> With kind regards,
>
> Werner,-