HDA1 audio questions

Discussion in 'Playback Devices' started by Travis, Sep 4, 2006.

  1. Travis

    Travis Second Unit

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    Setup: HDA1 connected to Pioneer 84VSXti via HDMI. Tosh set to auto in the audio menu. When playing a movie the Pioneer displays LPCM96 PLIIx cinema.

    Last night I watched CoR. DD was selected in the DVD menu. After watching the movie I wasn't that impressed with the sound. I went back and watched a few scenes over again and switched from the DD track to the DTS track. The DTS track blew it away. The sound was much fuller and way more crisp. At -10 the DD track was still a little on the quiet side. When switching to the DTS track -10 was almost unbearable. The bass was a ton better as well. I went back into the Tosh and changed the audio to PCM with the same result.

    I thought DD+ was as good as it gets. If so why does the DTS track on Riddick sound so much better. Am I not getting DD+ passed but just DD? Maybe I have something setup wrong on the Pioneer?
     
  2. Ken_F

    Ken_F Stunt Coordinator

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    Travis,

    Dolby TrueHD is as good as it gets. TrueHD is lossless audio.

    Dolby Digital Plus is just a revised version of Dolby Digital that 1) improves sound quality at lower bit rates, and 2) allows for higher bitrates -- up to 3Mbps -- to improve sound quality. According to Dolby, there is virtually no audible difference between Dolby Digital Plus @ 640Kbps and Dolby Digital @ 640Kbps.

    There are some HD-DVD titles with 1.5Mbps Dolby Digital Plus, but most seem to have 640Kbps. At 640Kbps, Dolby Digital Plus will sound better than the 448Kbps Dolby Digital found on the typical DVD, but not necessarily better than a 1.5Mbps DTS bitstream.
     
  3. Roger Dressler

    Roger Dressler Stunt Coordinator

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    From your description, it seems there is a difference in the playback loudness of the two tracks, probably due to Dolby's use of dialnorn. In this case, you have to adjust your volume control up by 4 dB (probably, but it varies based on dialnorm setting) when switching back to the Dolby track after DTS. That large a difference in playback volume will affect on the sonic details.
     
  4. Travis

    Travis Second Unit

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    That must be why when I turn up the volume on my Pioneer it says dialnorm+4 on the display for a second on HDDVD material. Which is strange as it doesn't say it when playing CoR. It sounds like more of a difference than just volume. I can turn the DTS track down by 5 db's and the sound is still more crisp. When Riddick is running from the Merc's and they are shooting the nets at him, when the nets hit the ground you can hear a noticable improvement in the sq. The bass is also stronger even at the lower volumes.

    If any one else has CoR and wants to try switching back and forth, that would be great. I'd like to know if anyone else has the same impressions.
     
  5. Ken_F

    Ken_F Stunt Coordinator

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    Well, current HD-DVD titles use DD+ at a minimum of 640Kbps. On DVD, the most you get from Dolby Digital is 448Kbps, so the sound on HD-DVD titles will be an improvement on that.

    However, a 1.5Mbps DTS track could still sound better than a 640Kbps DD+ track. There are no HD-DVD titles that have both 1.5Mbps DD+ and 1.5MBps DTS tracks, so we can't directly compare.
     
  6. Travis

    Travis Second Unit

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    I guess I was just confused as the Dolby Digital site touts 3mbps for DD+. I know that I am getting a proper feed, when I select bitstream my 84 displays PL and when I select auto or PCM it displays PCM. Usually when I listen to an HDDVD the display shows dianorm+4 when changing the volume but when playing CoR it doesn't. Hmmm.
     
  7. Roger Dressler

    Roger Dressler Stunt Coordinator

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    Your AVR can display the dialnorm offset from DD bitstreams on DVD because it sees that dialnorm data in the bitatream. When playing HD DVDs, the decoding is happening in the player, so your AVR only sees PCM, and cannot know anything about the dialnorm value. I cannot see how your AVR can otherwise display a valid dialnorm offset value.
     
  8. Travis

    Travis Second Unit

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    I must have remembered seeing it when I had the feed set to bitstream. It doesn't show on PCM.

    It's obviously tough to know if the DD+ track sounds better than the DD without swapping back and forth so I really don't have any reference. Based on information it would make sense that it SHOULD sound better. Is it enough that the average person can tell, who knows. Right now I can tell for certain that the DTS track on CoR sounds much better. We'll see on future tracks I guess.
     

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