Low Pass Filter Cut-off for LFE

rtbond wrote on 1/6/2013, 5:55 PM

Folks,

The article linked to below suggests that the value of the low pass filter cut-off for the LFE channel (Vegas project Audio tab, surround sound project) may be dictated by the DVD/Blu-ray authoring software. When using Sony DVD-A Pro 6 for disc authoring, does the Vegas Pro need to have a specific low pass filter cut-off or can one of preset be used (e.g., "80 [Hz] Dolby consumer/DVD")

http://www.sonycreativesoftware.com/surround_sound_mixing_in_vegas_and_acid

Comments

musicvid10 wrote on 1/6/2013, 6:00 PM

I recall that it is 120Hz in Vegas. I don't think it is adjustable.
I don't use LFE for my live events videos.

rtbond wrote on 1/6/2013, 7:04 PM

Yes, 120 Hz is the Vegas Pro 12 default. It is adjustable, based on the availability of the various Vegas presets and the details in the article I referenced in the original post.

Regarding not using the LFE for live event projects, what are the playback impacts on a 5.1 surround sound system if the LFE channel is empty? (i.e., is subwoofer performance effected?

Thanks!

--Rob

riredale wrote on 1/6/2013, 10:29 PM

I've never used the .1 channel.

If memory serves me right, it was meant as a "special effects" channel for theaters. Keep in mind that all the other Dolby channels are full-frequency range. Any low frequency information playing on any of the regular channels will be routed by your speaker setup to the woofer (I hate to call it a subwoofer, because that's technically supposed to be a device just for frequencies below a woofer's range; oh well, can't fight conventional wisdom).

There's a story going around that the first DVD release of Jurassic Park was mistakenly encoded so that the T-Rex clomps were routed solely to the .1 channel. For everyone with a conventional surround-sound setup, those sounds never came out, making for a very strange car chase. The disks were supposedly recalled and a fixed version released.

rtbond wrote on 1/7/2013, 11:47 AM

Thanks again. I was not sure how a surround sound playback system would handle AC-3 encoded with the LFE empty. Good to know the home theater decoder still routes low frequency content from the other channels to the subwoofer, regardless of the LFE content (I was under the false impression that the ".1" channel contained all the low frequency content) .

Best Regards