Sound quality of NeroVision Express DD 5.1 upmixing

vbimport

#1

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).


#2

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.