Encoding AVI+AC3 with QuEnc

[MrC]

Hi to all!

After lurking a lot on this fantastic forum, and having solved a lot of problems (or supposed problems ;) ), now I really have a question for everyone expert in QuEnc and/or AviSynth.

I have a AVI file containing an AC3 audio stream with 6 channels (5+1). I want to convert it to DVD.
By now my procedure is the following: encode video only with QuEnc, demux AC3 with VirtualDubMod and author M2V and AC3 with IfoEdit.
This procedure works. But it takes 3 steps and 3 softwares. :rolleyes:

I have tried to use QuEnc capability to encode AC3 streams (so 2 steps and 2 softwares), but if I feed in a 6ch AC3, it converts it to 2 ch AC3....
My first question is: can QuEnc encode 6ch AC3 or it "downgrades" to 2ch AC3? Is really a QuEnc problem or maybe I use a "poor" AVS script (see below)?
Second question: if I give to QuEnc a 384Kpbs 6ch AC3 and I tell QuEnc to generate a 384Kpbs AC3, will QuEnc re-encode it or leave it as-it-is?

AVS script used:
DirectShowSource("D:\Movies\avi_with_ac3_6ch.avi")
ConvertToYV12
LanczosResize(720,576,0,0.5)

QuEnc command line used:
QuEnc.exe -i "D:\Movies\avi_with_ac3_6ch.avs" -o "D:\Movies\avi_with_ac3_6ch.mpg" -b 3500 -maxbitrate 4500 -dc 10 -priority 5 -2 -mpeg2 -hq -vbr -aspectratio 4:3 -mpeg2mux dvd -audiocodec ac3 -audiobitrate 384 -auto -close

Tnx for reply

;)

Bye
________
CMX450C (http://www.cyclechaos.com/wiki/Honda_CMX450C)

[dragongodz]

if I feed in a 6ch AC3, it converts it to 2 ch AC3....
check your directshow ac3 decoder to see if its set to downmix. if it doesnt have an option then it may be downmixing automatically to your number of speakers. QuEnc will encode 5.1 ac3 when its fed 6 audio channels.

will QuEnc re-encode it or leave it as-it-is?
its being decoded through avisynth so will be re-encoded.

my opinion is your 3 step method will give you the best results.

[MrC]

check your directshow ac3 decoder to see if its set to downmix. if it doesnt have an option then it may be downmixing automatically to your number of speakers. QuEnc will encode 5.1 ac3 when its fed 6 audio channels.


Thanks for help, dragongodz.

I have AC3Filter 1.02a and I cannot find out any "downmix" option. There is the possibility to set Output to "3/2+SW 5+1 channels" and I did it, but nothing has changed....
.... can you suggest a more complete AC3 decoder?

;)

Bye
________
herbalaire vaporizer (http://vaporizers.net/herbalaire-vaporizer)

[dragongodz]

no acfilter should be fine.

There is the possibility to set Output to "3/2+SW 5+1 channels" and I did it, but nothing has changed....
did you set that on both the "main" tab and "mixer" tab ?

what you may want to try is loading MediaPlayerClassic, disable its internal ac3 decoding filter, quit MPC(needed for changes to take effect), reload it and load the avi+ac3. then look at what filters its reporting being used.

[MrC]

did you set that on both the "main" tab and "mixer" tab ?


I did it (ehm, now) and it works! Great! Thanks a lot!

Final question: can FFDShow be used as AC3 decoder? If yes, how?

:)

Bye
________
Honda MT250 (http://www.cyclechaos.com/wiki/Honda_MT250)

[dragongodz]

can FFDShow be used as AC3 decoder? If yes, how?
yes. from the windows menu find under ffdshow the "audio decoder configuration". in that select ac3 in "codecs" to be decoded by liba52.

[MrC]

yes. from the windows menu find under ffdshow the "audio decoder configuration". in that select ac3 in "codecs" to be decoded by liba52.

And then select AC3 in "Supported output sample format" from "Input/Output" page. ;)

Maybe this thread is becoming OT, but, which AC3 decoder is better betweeen AC3Filter and FFDShow?
________
C200 (http://www.cyclechaos.com/wiki/Honda_C200)

[dragongodz]

And then select AC3 in "Supported output sample format" from "Input/Output" page.
no you shouldnt need to set that in output. selecting 1 of the others selcts the output format such as raw or lpcm etc.

which AC3 decoder is better betweeen AC3Filter and FFDShow?
thats getting close to asking "whats best" which is not allowed under the forum rules. as for comparison, well i have no real preference. so try listening to each and seeing which you prefer. if you cant tell then maybe see if you can see which is using more of the cpu etc. all things being equel the decision will in the end be up to which you prefer to use. :)