This is my first post here so hello to everyone on this fine forum, please bare with me on this long post. I’ve been upmixing stereo audio to Dolby Pro-Logic 2 in a Dolby Digital 5.1 AC3 audio file, then Multiplexing it with the movie video, and authoring a DVD with it. I’ve been doing this using a guide called “Guide Stereo to 5.1 upmix using DPLII (2nd ED.)” that is posted at the Doom’s forum. It is a long process involving the use of the WinDVD InterVideo DMO in GraphEdit, to make a 6 channel Wave file with Pro-Logic 2 encoded into it. Then you have to convert the 6-channel wave file to a Dolby Digital 5.1 AC3 file using BeSweet. This works fine but is to time consuming. I was excited to hear that with NeroVision Express version 3.1.0.0 Nero has made it possible to upmix the stereo audio of a movie to Dolby Digital 5.1. So I wanted to test how well they implemented this feature. First I made a 5.1 soundtrack using the method above using a Jackson Brown song “Running on Empty” from the VH1 Live Video Awards. I had captured this from the TV broadcast and noticed it had a good Prologic 2 soundtrack. Using the same video file I then made a 5.1 video using NeroVision Express and there Dolby Digital 5.1 feature. I then De-Multiplexed both 5.1 videos with TMPGEnc and opened both 5.1 audio files in Audacity after converting them to 5.1 Wave files with BeSweet. I deleted all but the rear surround channels in both. I then listened to each of them separately noting how well the stereo channel separation was in the rear surround channels, and the overall sound quality. I was hoping that because Dolby Labs was involved in the Nero software the sound of their 5.1 upmixing would be up to Pro-Logic 2 standards. This did not prove to be the case. While it sounded better than Pro-Logic 1, and did have some stereo separation in the rear surrounds which Pro-Logic 1 does not, the separation was not as good as Pro-Logic 2. I also noted a flanging tunnel effect of the sound in the rear surrounds. The Nero 5.1 upmix did do a good job of taking the vocals out of the rear channels like it should though. Below is a screen grab of the waveforms, and frequency spectrum, of the rear surround channels of both the Nero 5.1 soundtrack, and the ones produced by Dolby Pro-Logic 2. You can see that in the frequency spectrum’s the Nero 5.1 does not have near the high frequency information that the ones produced by Dolby Pro-Logic 2 do, it is more like what you would expect from Pro-Logic 1 with it’s 10,000kHz frequency limit in the rear channels. In conclusion, I was hoping for a fast way to upmix to Dolby Digital 5.1 but I will probably only use Nerovision for movies, and use the InterVideo DMO method for music videos, and important material. I also noticed that under the “More<<” button in Recode the “Default Video Options” button is missing, so I don’t think you can use the Dolby Digital 5.1 upmixing feature in Recode to make Nero Digital MPEG4 files with 5.1 soundtracks (you still can if your source has 5.1 sound).

For one thing, you won't improve audio quality of two-channel material by upmixing to 5.1, regardless of the software used. You may make it sound "more interesting", though.