Mixing down from 5.1 to 2.0

[drsox]

Some DVDs only have AC3 5.1 audio but with 2 speakers for playback some of the audio is lost and makes the DVD unwatchable. How do I remix the audio from 5.1 to 2.0 ?

I'm playing back with a Netgear EVA8000 from ISOs stored on a NAS.

[tebasuna51]

Netgear EVA8000 seems don't support AC3 at all (5.1 or 2.0):

Digital Media File Formats
...
- Video Formats: MPEG1, MPEG2, MPEG4, AVI, WMV, Xvid
- Audio Formats: MP3, WAV, WMA, AAC, FLAC

Then I don't know how you can play DVD ISO's.
Maybe you need rip your DVD's to avi (Xvid-mp3), search in 'Video encoding' forum.

[drsox]

The EVA8000s I have play AC3 just fine as part the ISO files I create. If I open any ISO I have, DVDshrink lists the Audio as AC3 2-ch English. The one with the poor sound lists as AC3 5.1-ch English.

AC3 is on the supported formats list : http://kb.netgear.com/app/answers/detail/a_id/94/session/L2F2LzEvc2lkL2J4M2VXKlRq.

[sneaker_ger]

I don't know that particular device, but it would be the first one that's not able to down mix to 2 channels on the fly I've ever heard of. I'd look into the manual or into the setup. I bet there's some point which lets you set the speaker number and from there on all files should play fine.

[drsox]

Thanks. I found it on an Audio set up screen. Stereo output as a selectable option - automatic downmixing from whatever multi source.

[tebasuna51]

If new firmware support AC3 must have also a downmix function to output stereo, but if you want make your proper downmix you can use:

eac3to multichannel.ac3 stereo.ac3 -192 -downmix -normalize

EDIT: Sorry, thanks nurbs, must be:
eac3to multichannel.ac3 stereo.ac3 -192 -down2 -normalize

[nurbs]

Shouldn't that be eac3to multichannel.ac3 stereo.ac3 -192 -down2 -normalize

[Blue_MiSfit]

Indeed.

If you're going to all the hassle of transcoding, why not use a more efficient format like AAC?

Unless of course you're trying for DVD compliance. You should still be able to mux AAC + MPEG-2 into an MP4 or MKV. Erm.. you can mux MPEG-2 in MP4, right???

~MiSfit