2.0 to 5.1+ Dolby Prologic II Upmix Guide
Sometimes you want to upmix Dolby 2.0 or PCM to more channels. Sometimes you may have an mp3 file or audio CD with content you want to add to an edit you are working on, but you don't want to work in stereo.
This guide will help you do that.
The best part is dialog will be in the center speaker and reduced or removed from your other channels, rear channels will have ambience and your subwoofer should kick a little.
ffdshow (http://sourceforge.net/projects/ffdshow-tryout/files/) is a DirectShow filter that supports pretty much any audio/video format you can imagine. It's constantly being updated, so grab the latest version.
This guide was tested with Beta 7 revision 3154. Other versions may or may not work as well.
GraphStudio (http://blog.monogram.sk/janos/tools/monogram-graphstudio/ is a fork of GraphEdit. While there is nothing wrong with the original, as far as I know it hasn't been updated in almost a decade.
0) Rip your audio source to your computer. I hope you know how.
Install ffdshow and unpack GraphStudio.
Your source audio file can be just about anything as long as you can play it in a directshow player.
You should not need to set up ffdshow as the audio decoder for your source file, we won't be using that component.
1) Start GraphStudio, select file/render media file. Find your source audio and open it.
2) You will now see a graph that shows how the decoding components are chained together. Delete "Default Directshow Device" box by selecting it and hitting the "Delete" key. If "ffdshow Audio Decoder" is present, delete that as well.
3) Select Graph/Insert Filter.
Select "ffdshow Audio Processor", and click insert.
Select "File Writer", and click insert.
You will be prompted for a location to save your file. Find a directory with enough space and make sure your file ends in .ac3.
Click the 'X' at the top of the window to close the filter selection screen.
4) Double click "ffdshow audio processor".
(Except for the options below, all other filters in the left column should be unchecked.)
If your source is a flavor of Dolby to start with, click "Decoder Options" on the left and uncheck "Apply dynamic range compression if available" on the right.
In the left column select "Dolby Decoder". On the right:
Check "Apply Dolby Pro Logic II decoding to all stereo sources". The default 'Rear channel delay' is 20ms. You can adjust it if you want.
On the left click "Volume". On the right:
Click the check box for "Volume".
Move the "Master volume" slider to 50%.
You might need the volume even lower. Since the center channel will be louder than your left/right channels currently are, you must soften the volume or you will overdrive the sound and it will clip.
If the source was not originally DVD (CD, mp3, etc.) try 25% first.
If your source is not DVD, click "Resample" on the left. On the right:
"Resample to" select 48000 Hz.
"Mode" select "libavcodec highest quality".
Check "Resample always".
On the left, click "LFE Crossover". One the right:
120Hz is a good lowpass frequency. You may want to experiment.
If you want more subwoofer activity, you can adjust your gain, otherwise set it to 0db.
If you want you can remove the crossed-over audio from the rest of your channels, but it's not necessary.
On the left click "Mixer". On the right:
Set the "Output speaker configuration" as desired.
"3/0/2 - 5 Channels" and checking "LFE" will give you DD5.1.
"3/2/1 - 6 Channels" with LFE is DD6.1 EX
"3/2/2 - 7 Channels" with LFE is DD7.1 EX
You get the idea. You can go lower, or have no LFE as desired.
Everything else should be unchecked.
The "Custom Matrix" is good if you want to do some custom audio mixes. Say you want only the dialog channel, you can output the center and leave the rest blank. Or say you want all the audio WITHOUT the center channel... you can do that too.
On the left click "Output". On the right uncheck everything except:
"Supported output sample formats", check (S/PDIF encode mode) & select your "Bitrate" as desired.
448 is good for 5.1, 384 is acceptable if you want to save space, 640 is acceptable but extreme.
Check "Allow direct-to-file output".
5) Your source file box should already be connected to a decoder of some sort (it will vary by source). Find the last filter in the chain and using your mouse, drag from the out/output tab of that filter to the 'In' on the 'ffdshow Audio Processor'. An arrow should appear connecting them.
Additional filters may be automatically added. That's fine, just make sure they don't have strange settings that will interfere. If 'ffdshow Audio Decoder" has been added to the chain, go into the options (double click) and clear every checkbox (especially the mixer & Decoder Options). If the audio is pre-processed it may not upmix properly.
Drag a line from the 'Out' of 'ffdshow Audio Processor' to the 'In' of your output file (the box will be whatever you named it).
6) Click the |> (play arrow) at the top. It will grey out. Wait until it reappears.
You should have a file to your specifications just where you wanted it. Give it a listen, you may need to make tweaks and try again.
If there is interest, I may revisit this guide with info on outputting wave audio for encoding with 3rd party encoders (like Soft Encode or DTS). You can also use PowerDVD in a similar manner to access their official DPL2 decoder and DTS Neo:6.
The Doom9 guide can give you additional (if out of date) information. http://forum.doom9.org/showthread.php?t=83384
Are screenshots needed?
5/18/2010 by Doctor M
Please do not repost this on other forums... at least until we've worked the bugs out.