Best waf converter

If you want to retain 5.1-channel when processing conversion, just choose a output format, which is using AAC or AC3 codec to encode audio, from the drop-down list of “Format”> “Common Video”, like MP4, 3GP, MOV, MKV, M4V, and here I select MP4 for example.
Simultaneously download and convert YouTube videos to MP4 for iPod and iPhone
As a YouTube enthusiast, I have installed different Firefox plug-ins to download my favorite YouTube videos, while as the accumulation of more and more plug-ins, my Firefox often collapses and refuses to go in a correct way. To keep my Firefox clean and working well, I have to find a green tool to take place of the plug-ins; meanwhile, it is expected to finish downloading and converting to MP4 simultaneously, so that I can put them to my iPhone and iPod for playback without trouble.
I did a Google search, found a program called YouTube Converter, which has a good rank in Google, but at first, I did not trust it at all, and just tried its trial version, after several attempts, I found it is really easy-to-use and powerful, which can process downloading and converting at the same time without any video and audio out of sync issues. Moreover, its built-in codecs avoid disturbing my computer system, which is what I need most. Thus finally
I purchased it, now I share it here, and hope you can get what you want from it as well, and also express my gratitude to it.
After that, press “Settings” and you will get a “Profile” window, in this window you are allowed to set “5.1 Channels” as the output channel, also, you see, the audio codec used here is AAC.
Case two: change 5.1-channel to two-channel stereo.
Suppose you want to convert 5.1-channel of the source files to two-channel stereo as the object track, and then just follow the way upside. Unlike 5.1-channel, almost all formats listed are available to complete stereo conversion, audio codec are not strictly requested as well. As soon as you get into the “Profile” interface, just select “Stereo” as the output channel. Afterwards, Pavtube video converter will finish the rest work for you.
Of course, if the number of output channel is less than the original one, such as the above mentioned source is 5.1, should be encoded into a two-channel, at this time, Pavtube will mix the sound of 5.1-channel in a certain proportion, and generate the ordinary stereo only with channels L and R.
Case three: change two-channel stereo to 5.1-channel.
On the contrary to case two, if the number of output channel is greater than the source channel, like changing two-channel stereo to 5.1-channel, in this condition, Pavtube video converter will only fill in the channels L and R, and others will be merely stuffed with silence. So to some extent, we can say this kind of conversion is meaningless.