Olivier Rolland wrote:

Hi,

I want to encode a 5.1 DVD in a stereo avi with audio normalised. What is the best ways to get that:

-channels 2 -af volnorm or -channels 2 -af channels=2,volnorm or -channels 2 -af volnorm=2,channels ?

Can I omit "-channels 2" ? What is the precedence between -channels and -af ?

I could say that -channels has higher precedence, but that might be misleading by way of lack of information, so: "-channels" requests that the audio decoder provide that many channels of output. Note that "request" is the operative word. Some decoders won't downmix and (as far as I know), none of them upmix. "-af channels" is a filter for changing channel layout and possibly emitting a different number of channels. As a filter, af_channels has no control over the number of channels it receives, though you can configure af_channels to ignore channels you don't want. Specifically for your case, you only need to use "-af volnorm", since "-channels 2" is the default. -Corey