-
5.1 Audio on Encore CS4 – Help Please!
Hi
I am trying to include a 5.1ch audio track on a Blu-ray disc authored using Encore CS4 but having tried various file formats and encoding methods etc, I only seem to be able to get Dolby 2.0 (Stereo) when playing the disc.
I realise Encore will not encode 5.1ch itself and that I need to provide a pre-encoded 5.1ch file, I thought I had done this (several times!) but am still getting the same result.
I’ll explain what files I am using and what I have tried so far and am hoping someone can tell me where I am going wrong or what process I should be using.
My original files are HD Transport Stream (.ts) files and I have demuxed these to .m2v video files and .ac3 audio files. I think eventually I used ProjectX to split them but I’m not 100% sure as I tried various programs!
I have tried importing the .ac3 files directly into Encore but I end up with stereo sound on my blu-ray disc.
From what I can tell, the .ac3 files are 5.1ch 48khz audio.
In Encore, it seems a little strange but with an audio file selected in the Project window, I don’t seem to be able to select ‘Dont Transcode’ from the Properties window and the list of transcoding options seem to relate more to the video than audio. This may be normal but it seemed a bit odd to me.
I then tried changing the .ac3 files to WAV using HeadAC3he which also shows the AC3 file as being 5.1ch. Exported/converted WAV files show in Windows as being 6ch WAV but after writing the Blu-ray in Encore, I still end up with 2ch stereo.
I have also tried selecting PCM in the Project Settings and although it did change the audio track to PCM, it was still only 2ch stereo.
The final thing I have tried is to use a Surcode DTS encoder but that just gave me static!
If anyone can point me to where I am going wrong, that would be great as this is driving me mad! Everything else on my blu-ray disc works as I want it so its just this 5.1ch sound left to sort.
Regards.
David -
15 Replies
-
You cannot let Encore re-encode the audio file for any reason. You must leave it as the ac3 file from your demux process. You are probably getting the correct audio stream when you demux, but you should double check, because sometimes dvd’s will contain both 2ch and 5.1 channel streams, and you must select the correct one.
Double check your timeline in encore to make sure you don’t have multiple clips lined up, and make sure the video starts at the very beginning of the timeline (don’t try and add a little space at the beginning), otherwise encore will need to re-encode the audio, and it will be 2ch.
If you don’t give encore a reason to transcode it, it won’t, and your clip will remain 5.1ch.
Jon Geddes
Motion Graphics Designer
http://www.precomposed.com -
Hi Jon
Thanks for you reply.
My original transport stream was split into 5 parts due to its size so after the demux I actually have 5 .m2v video files and 5 .ac3 audio files which I have placed one after another on the main timeline.
Could this be the problem? If it is, is there a recommended tool for combining the files into a single video file and a single ac3 audio file?
I don’t think there is a 2ch stream in the file, I believe it only had a surround audio stream. It was originally an HD stream sent to cinemas from a live concert.
It sounds like Encore is re-encoding the audio for some reason but I am not sure how to stop this.
David
-
[David Andrews] “I actually have 5 .m2v video files and 5 .ac3 audio files which I have placed one after another on the main timeline. “
That’s your problem, right there.
AC3 files have null data blocks at the end of their file structure. When they are added together in a timeline, they will gradually introduce a loss of sync with video.
In order to address this problem, Encore decompresses multiple AC3 files in a timeline to raw audio, and then recompresses these clips into a single AC3 file, which eliminates the problem with a loss of synchronization if otherwise unaddressed.
The problem is of course that Encore’s AC3 encoder is Dolby Digital 2.0 only, and this is why your clips are being re-transcoded.
The solution is either to combine the 5.1 AC3 files elsewhere to a single 5.1 AC3 file (sorry, I don’t have any specific suggestions, but there may be freeware tools that can do this – start at videohelp.com), or use separate timelines for each video/audio pair.
-
Thanks Joe.
I’ve done some searching for AC3 joiners so I have a few things to try. Hopefully I won’t encounter video/audio sync issues afterwards. Its not perfect at the moment (original wasn’t perfect to begin with) but its acceptable considering the source material.
As long as there isn’t a delay in moving from one timeline to another, that may also work so I’ll also give that a try.
Regards.
David -
If you didn’t want to join them, you could create a separate timeline for each clip, then use a Playlist (not a chapter playlist) to have them all play in sequence.
Jon Geddes
Motion Graphics Designer
http://www.precomposed.com -
Hi Jon / Joe
Thank you both so much for your help.
I have joined the 5 AC3 files into a single file, re-imported it into Encore and now have a 5.1ch Dolby Digital track for my blu-ray, which is fantastic.
Regards.
David -
Very cool.
Would you mind sharing which tool you combined the AC3 files with (for future reference)?
-
Hi Joe
Yeah, sorry, I should have included some detail in my last post.
In the end I didn’t use a tool, I found a number of pages detailing how to use the basic DOS copy command with the /b switch so I tried that and it worked!
Basically, if you have, for example, three .ac3 files called part1.ac3, part2.ac3 and part3.ac3.
Open a command prompt, change to the directory where the ac3 files are located and type:
copy /b part1.ac3+part2.ac3+part3.ace completefile.ac3
This will create a new file called completefile.ac3 which is the other three joined together.
I believe this also works with the .m2v video files as well but I haven’t needed to join those.
Regards
David -
David, Jon, Joe,
Thank you for this post. It is enormously helpful.
David I am curious about how you used DOS to combine the AC3 files. Did you do this in Windows XP running a DOS terminal window? I’m surprised you were able transcode/combine the AC3 files with a simple DOS command. Was it really as simple as that, or am I missing a detail here?
Thanks,
Stuart
-
Hi Stuart
It feels like a long time ago when I posted the messages above!
I was using Vista at the time but the command is a DOS command, so basically you go into XP, Vista or Winodws 7 as normal, then open a command prompt, move to the directory you have your AC3 files stored in and type the command.
For example (from my post on Apr 24, 2009 at 10:21:57):
copy /b part1.ac3+part2.ac3+part3.ac3 completefile.ac3
See my post above for a full description of the command and filenames etc.
There isn’t any transcoding or anything much going on. the /b parameter on the copy command is for binary copy. This means it isn’t doing anything with the content of the files, just simply appending one to another.
The operation is almost instant.
Regards,
David
Reply to this Discussion! Login or Sign Up