AC3 - change 6ch to 2ch

[K401]

Is there a guide on how to change 6ch to 2ch because I find with 6ch the background audio is louder than the speech somebody told me if you haven't got surround sound you need 2ch audio to avoid this.
I've found Downmix and AC3 machine but I need a guide because I've got no idea how to use it.
I'd be grateful if someone could help me out.
Thanks alot.
K401

[DSPguru]

there's an active link on AC3Machine to the relevant guide.

[K401]

Thankyou DSPguru, for your help, but I've got a probelm in AC3 machine.
When I get to Input of AC3 file I go to the film in the browser but it doesn't reconise the AC3 file. Any idea's.
Thanks alot
K401

[DJ Bobo]

Why bother using AC3 when there is MP3 & MP2?
With MP3 you won't get over 160kbps if you encode in VBR mode and get nevertheless "perfect" quality (use r3mix or alt-preset)
With MP2 stay over 192kbps (Stereo, *NOT* Joint Stereo) and all will be fine!

[iago]

@K401

Are you using AC3Machine 0.41? However, 6ch AC3 to 2ch AC3 conversion (with AC3Machine) will most probably result in a much more silent file than the original AC3 audio ;). Either keeping the original AC3 audio or converting to MP3 (for 2CD encodes) seems more reasonable than 6ch AC3 -> 2ch AC3 conversion imho.

regards,
iago

[DSPguru]

my advice would be :
either you do 5.1ac3 -> 5.1ac3 with lower bitrate
either you go for 5.1ac3 -> 2.0 ogg vorbis.

[MaTTeR]

Originally posted by DJ Bobo
With MP2 stay over 192kbps (Stereo, *NOT* Joint Stereo) and all will be fine!

Just curious as to why you prefer Stereo over the likes of Joint or Dual when trancoding to MP2?

Edit- Just noticed the comment about 192kbps also. Are there problems below this bitrate or do you make this statement in regards to quality? Again, just curious:)

[K401]

iago thankyou for your help. I converted the AC3 to MP2 and Spruce wouldn't except it. Can you give me any idea's where I'm going wrong.
Thanks alot
K401

[K401]

I think I've made a mistake I converted to MP2 and I read you posting again and it's MP3. Will Spruce except MP3?

Thanks alot
K401

[DSPguru]

Originally posted by MaTTeR
Just curious as to why you prefer Stereo over the likes of Joint or Dual when trancoding to MP2?http://forum.doom9.org/showthread.php?s=&threadid=22344

[MaTTeR]

Hrm..I had never seen that thread before, very interesting. I've always found that dual channel mode seems to have better surround FX to my ears. I only tried it awhile back because most of the big (x)VCD boards that exist also suggested using it and I must say it sounds very impressive depending on the movie. Anyways sorry to take this thread off topic. Thx Dg.

[DSPguru]

np, Matt.
btw, Stereo mode is still more advised than Dual channel.
Joint Stereo is mostly advised for mono streams ;).

reminder : above is only relevant for mp2.

[MaTTeR]

Well that was actually my problem too, I was thinking in terms of MP3. So now it's more testing I need to perform this weekend:)

[dvd_maniac]

I want to change a 5.1 to 2 channel ac3, is this possible? I have softencode 5.1 and ac3machine ver any help would be awesome.

[dvd_maniac]

I have found the same problem in ac3machine not accepting ac3 files, what I did was type the path/name of the ac3 in the input line. Then do everything else as normal and it worked for me. 5.1 converted to 2ch ac3 ready for input into spruce, dvdit or whatever.
Hope this helps you out.