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Hybrid VBR Resolution switches in Panasonic recorders.

Discussion in 'Blu-ray & DVD Players & Recorders' started by bobones, Nov 25, 2003.

  1. bobones

    bobones
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    It seems that the E50 (for one) shifts resolutions midway through recordings (say from 704x576 to 352x576), which causes problems why trying to re-author on a PC.

    I first noticed this when TMPGEnc DVD Author threw up errors while attempting to import RAM VR mode recordings that it said had mixed resolutions.

    Renaming the .vro to .mpg and importing as a file would get round the error message; however, at points where the resolution dropped, DVD Author would display the image in one half of the viewing window while the other half was blacked out. (A limitation of the software's ability to handle the sudden drop in horizontal resolution).

    The only way I know to get around the DVD Author problem is to re-encode to a fixed resolution while exporting the VRO as MPEG-2 using the DVDMovieAlbumSE software supplied with my Panny PC burner. (Is there any widely available software that can do this?).

    Anyway, the interesting thing I noticed was that this downshift in resolution occurred at around 18mins into a 1.5hr SP recording (not near the end) at a point where there was a lot of movement and activity in the scene. (Precisely the point in the current OneTel advert where the Helicopter blows all the leaves from the guy's garden). The resolution then remained at the lower setting for around 2 minutes, and then switched back a few seconds after the ad break finished and contined at the higher resolution until the end of the recording.

    It looks to me like the machine detects that a much higher bitrate than allowed by the current recording mode (SP in this case) would be needed to prevent artifacting, and, as a lesser of two evils, decides to drop the resolution until things stabilize again.

    These switches in resolution may be imperceptable if you're viewing from RAM or HD in the recorder itself, and actually improve PQ by preventing blocky artifacts; however, they're clearly noticeable in WinDVD as the picture stutters slightly and a a new chapter is started.

    The obvious solution (other than to re-encode at a fixed resolution with something like DVD MovieAlbumSE) is to change the recorder's Hybrid VBR Resolution setting to "fixed" from its default "auto" setting. Has anyone done this, and have they noticed an increase in blocky artifacts as a result?

    I don't have a HD recorder, but I'd think these resolution shifts would have ramifications for dubbing from HD to dvd-r on these machines, as surely all recordings must be re-encoded to ensure a fixed resolution througout the dvd-video created on dvd-r?

    Apologies for rambling on a bit, but can anyone shed any more light on this?
     
  2. kenfowler3966

    kenfowler3966
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    It is recommended to change to fixed if you wish to edit and archive via a computer, and also some players can't handle the resolution changes.

    If you have a compatible player and/or play back from the panny you will get better visual results leaving in auto, as blockiness is reduced in busy scenes at the expense of detail, but it should recover later.
     
  3. nwgarratt

    nwgarratt
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    I archive all the time to the computer and never had this mixed resolution.

    I have had DVD Author play up discs that has both 4:3 and widescreen on the same disc though.

    I have my VBR Resolution settings set to automatic. What does the fixed setting do?
     
  4. bobones

    bobones
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    The "fixed" setting for Hybrid VBR Resolution stops the recorder dropping the resolution (say from 704x376 to 352x376) in scenes where the bitrate isn't high enough to cope. In "automatic" you'll find that some of your recordings may change resolution in the middle of a single programme. TMP DVD Author can't handle programmes where this happens and gives an error message and fails to import. Changing the vro to mpg doesn't get around it either. Happens quite often to me so I'm sure you'll come up against it eventually.
     

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