AC3 Question

[Madz5]

Is there a way to change AC3 5.1-ch to AC3 2-ch?

[edDV]

That usually isn't necessary. AC-3 decoders can play as 5.1 or 2.0/2.1.

[Madz5]

The reason is I created an ISO using avstodvd prog, all files were from the same source. As i opened the ISO on dvdshrink, i noticed that the first file played fine the audio was in synch with the video, but in rest of the files (2-9), the sound was like chipmunks.
Then i noticed that the first files audio was AC3 2-ch English were as the rest of the files were AC3 - 5.1-ch English...i'm assuming thats why the sound is like that?

[Bonie81]

Can be done using GraphEdit and Channel Downmixer by Trombettworks.
But,de-muxing 5.1ch --> GraphEdit and Channel Downmixer ---> 2 ch ---> muxing to video, without any delays is another issue. Alternatively give WinAVI Video Converter a try!

[Madz5]

Im kind of confused, i just looked up the properties of the actual files that i used avstodvd to form the ISO. Details for the audio channels for all files say 2 (stereo). Shouldn't they have stayed at that?

Anyway i'll give WinAVI a try, thanks bonie81.

[poisondeathray]

easiest way to downmix is to use megui (uses behappy) or eac3to (with commandline), but 5.1 audio is unlikely to be your problem

what were the source files, and what was their format ? use mediainfo if you don't know

[Madz5]

They are anime episodes, all dowloaded from the same source. They are in mkv format, what i don't get is why one files audio was fine and the rest weren't.

[poisondeathray]

Were they aac audio ?

Not sure why 2-9 didn't convert properly, you can convert them separately if you want

[johns0]

Most likely the ac3 5.1 were 640kbs and avstodvd re-encoded them to 448kbs 5.1 and screwed them up.

[Bonie81]

As said by johns0...

Most likely the ac3 5.1 were 640kbs and avstodvd re-encoded them to 448kbs 5.1 and screwed them up.

If you post AVStoDVD log here, probably avstodvd author can help.
When anyone uses AVStoDVD or any other DVD Authoring software, It is always recommended to have all files in same format in terms of video and audio specifications. Very few DVD Authoring tools can handle various types of files at once.

You can convert all your video clips to AVI+AC3 (2ch) using WinAVI or any other good converter by maintaining same video (size, bitrate, aspect) and audio (bitrate and channels) specs and then throw into AVStoDVD. Suugested bitrate for V>2000kbps A>320kbps. For AVI+AC3 or mpg+AC3, i guess HCenc will take care of. While in case of AVI+MP3 QuEnc will kick in if you are using AVStoDVD.

[Madz5]

Well heres the log.

I'll check WinAVI out, thanks.

[_MrC_]

The reason is I created an ISO using avstodvd prog, all files were from the same source. As i opened the ISO on dvdshrink, i noticed that the first file played fine the audio was in synch with the video, but in rest of the files (2-9), the sound was like chipmunks.
Then i noticed that the first files audio was AC3 2-ch English were as the rest of the files were AC3 - 5.1-ch English...i'm assuming thats why the sound is like that?

All your input mkv files have AAC audio track with 2 channels.

Make sure you have properly configured your AC3 directshow mixer to output 2.0 channels and not 5.1 channels. If you have installed (only) ffdshow then AVStoDVD will do it for you, but if you have installed other AC3 decoders (like AC3Filter), then you have to do it by yourself.



Bye

[Madz5]

I have only ffdshow installed, i'm not sure if i'm checking the wrong options?

And am i supposed to leave ffdshow program open while creating the ISO file?

[Madz5]

[Attachment 4472 - Click to enlarge]

[Attachment 4473 - Click to enlarge] is this ok? I followed one of the guides to check some of these options

Tried once more, coming up as 5.1-ch, it seems to be inputting it as 5.1-ch? -->

[_MrC_]

Madz5,

the Aften input format is determined by your AC3 directshow decoder setup. Please make sure that ffdshow output mixer is setup as 2/0/0 with LFE off.

To check if ffdshow is being used as AC3 decoder, you can verify with GraphEdit (go to 'File'/'Render Media File').



Bye

[Madz5]

I'm finding the graphedit program a lil confusing, can anyone suggest a good guide?

[Madz5]

I also have avisynth installed, does that affect the ffdshow somehow?

I'm using windows 7, maybe I am supposed to installWin7DSFilterTweaker for the ffdshow settings to take place?

[Madz5]

Just to let you guys and anyone else know if they have the same problem, I converted the vids to divx format and then used avstodvd to create the ISO folder, then used dvdshrink and after burning it with imgburn, the dvd came out perfect. Ffdshow did seem to kick in for the divx format, just didn't for the mkv format and one other thing, the number of channels for mkv format where 6 and for divx format were 2.

Thanks for all the help and advice guys.