Questions on LFE channel and DVD low frecuency information

Discussion in 'Archived Threads 2001-2004' started by Jonathan T, Dec 26, 2002.

  1. Jonathan T

    Jonathan T Second Unit

    Joined:
    Nov 6, 2002
    Messages:
    360
    Likes Received:
    0
    Trophy Points:
    0
    The LFE channel is a seperate channel of low frequency information, not a channel containing all low frequency information from all the other channels, right? When playing a DVD with just 2 channels, is the LFE channel mixed into these channels, or is it left out? I'm asking this cause I was just watching Star Wars on my mom's TV, she's using the TV speakers. I caught the end of the movie with the fight between Yoda and the other dude (whatever his name is) When they whipped out their light sabers, the TV started to ratte and sound was very distorted as the speakers were trying to reporduce a low frequency sound. Wouldn't this information be in the LFE channel?
     
  2. Damin J Toell

    Damin J Toell Producer

    Joined:
    Mar 7, 2001
    Messages:
    3,762
    Likes Received:
    6
    Trophy Points:
    0
    Location:
    Brooklyn, NY
    Real Name:
    Damin J. Toell
     
  3. Rick Blaine

    Rick Blaine Stunt Coordinator

    Joined:
    Nov 12, 2002
    Messages:
    53
    Likes Received:
    0
    Trophy Points:
    0
    Also note that many times if there is no 2.0 version of the mix on the DVD, studios will downmix the original 5.1 tracks for DVD. In that process some of the LFE audio is routed to the Left and Right channels so it will not be totally lost when played in Stereo or Pro-Logic modes.


    RB
     
  4. Inspector Hammer!

    Inspector Hammer! Executive Producer

    Joined:
    Mar 15, 1999
    Messages:
    11,061
    Likes Received:
    1
    Trophy Points:
    0
    Location:
    Houston, Texas
    Real Name:
    John Williamson
    Their is low end in the other 5 channels in a DD 5.1 track, and if you've got good enough speakers to handle it you can set your speakers to "large". If your running smaller and less efficiant speakers, set them all to "small" this will redirect all their low end to your sub.

    Of course this is on a DD 5.1 set up, and as stated, when your running 2.0 stereo the LFE channel is cut off because 2 channel stereo doesn't contain it's own separate LFE channel. If you have sub connected, the only bass you'll hear coming from it in 2.0 is bass from your two main channels, and that's only if you choose to have the sub active during 2.0 material. In a 2.0 configuration without a sub like in your case, all your hearing is the bass mixed into the two stereo channels.

    The reason your mom's speakers bottomed out was because you simply have too much bass going to them, the bass extended below the point than the speakers were rated to handle, try reducing the bass output. It will be less thrilling without that intense low end, but if you continue to keep your bass that high you risk damaging the speakers inside the tv.
     
  5. Brian L

    Brian L Cinematographer

    Joined:
    Jul 8, 1998
    Messages:
    2,943
    Likes Received:
    26
    Trophy Points:
    1,610
     
  6. Inspector Hammer!

    Inspector Hammer! Executive Producer

    Joined:
    Mar 15, 1999
    Messages:
    11,061
    Likes Received:
    1
    Trophy Points:
    0
    Location:
    Houston, Texas
    Real Name:
    John Williamson
    Brian,
    you may already know all this, but setting up a system the way you described can potentially rob it of one thing and certaintly robs it of another...
    First, setting the mains to "large" and the center to "small" can throw off they're timbre matching resulting in sound not matching when panning across the front soundstage. I'm using large front speakers as well and I have this problem even though I have all of my speakers set to "small", I correcetd this by playing the test tone on AVIA called "pink noise match of center speaker" in the certification and Evaluation area of the disc. Listening carefully to the test tone for changes in both the tone and pitch as it moved back and forth, I then played with my treble and bass controls until my front speaker sounded very similar to my center, this of course was after I calibrated so volume differences were not an issue. The bass control is at neutral, I played hell trying to find just the right combination between bass and treble let me tell ya! [​IMG]
    The second thing Brian, even though the system sounds great, and i'm sure it does, your freind is not feeling all of the REAL floor quaking, house threatening low end that 5.1 tracks have to offer without using a sub because he's not utilizing the .1 LFE channel where all of it lies.
    However in the end it all comes down to if it sounds great to him, everything I said is just FYI, but again you probably knew all of this already. [​IMG]
     
  7. Jonathan T

    Jonathan T Second Unit

    Joined:
    Nov 6, 2002
    Messages:
    360
    Likes Received:
    0
    Trophy Points:
    0
    Aright guys, thanks.
     
  8. Nick_Scott

    Nick_Scott Second Unit

    Joined:
    Sep 9, 2001
    Messages:
    322
    Likes Received:
    0
    Trophy Points:
    0
    Were you playing the 2.0 or the 5.1 track?
    You will find a huge difference in bass in a stereo system.

    Nick
     
  9. Adam Barratt

    Adam Barratt Cinematographer

    Joined:
    Oct 16, 1998
    Messages:
    2,343
    Likes Received:
    1
    Trophy Points:
    0
    Real Name:
    Adam
    It's important to differentiate between the LFE channel and a 'subwoofer' channel (something I think a few here are failing to do). The LFE channel isn't a subwoofer channel, so it should never contain material that isn't also present in other channels. Losing it doesn't mean you will lose any bass content.

    All of the main channels in a DTS or Dolby Digital soundtrack are full range, and capable of carrying the same bass content as the LFE channel (down to ~3Hz, unfiltered). The LFE channel simply increases bass headroom by playing this material at a higher relative volume, but it doesn't go any lower than any other channel.

    The LFE channel is normally regarded as disposable, as illustrated by the downmixing practice of discarding LFE content. Losing the LFE channel should have no effect on the bass content of a soundtrack, just the volume it is heard at. No bass material will be 'chopped off'.

    Adam
     
  10. Joel Fontenot

    Joel Fontenot Supporting Actor

    Joined:
    Aug 9, 1999
    Messages:
    950
    Likes Received:
    207
    Trophy Points:
    610
    Location:
    Baton Rouge, LA
    Real Name:
    Joel Fontenot
     
  11. Nick_Scott

    Nick_Scott Second Unit

    Joined:
    Sep 9, 2001
    Messages:
    322
    Likes Received:
    0
    Trophy Points:
    0
    Joel-
    I though you meant SW #1 which did have both tracks.
    In the case of SW:TPM, the 5.1 track had nearly all the bass in the LFE channel, so it sounded weak when downmixed. However, the 2.0 track had lots of bass.

    In the case of SW:AOTC, they might of applied the same process of putting most of the bass in the LFE, but you usually only see that on DVDs that also include a 2.0 track.

    Nick
     

Share This Page