What actually controls widescreen switching?

Discussion in 'Playback Devices' started by Steve J Taylor, Aug 31, 2003.

  1. Steve J Taylor

    Steve J Taylor Auditioning

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    I have a Panasonic DMR-E50 DVD recorder and a Toshiba 36ZP18Q widescreen TV, connected using S-Video.

    If I play a commercial DVD, the TV automatically switches to 16:9 mode.

    If I play a recording of widescreen material (from digital satellite) the TV does not automatically switch to 16:9. If I switch the TV manually, the display is fine.

    So, what actually makes the TV switch modes automatically when I play a movie DVD?


    Things I have tried:

    The TV is set to "automatic format", and the DVD recorder to "TV type = 16:9". Since a commercial DVD switches OK, I think all the settings must be OK.

    I have re-authored the recordings using TMPGEnc DVD Author and IfoEdit. I have set the aspect ratio in the .ifo files to 16:9 (the Panny sets the .ifo files to 4:3).

    I have checked the mpeg data headers with AspectChanger. This shows that the data is in 16:9 format.

    I have made a backup copy of a DVD that I own, using DVD Shrink, and checked the .ifo files and mpeg data. They were correct.


    I cannot get any recording or backup to auto-switch my TV. If I switch manually they display correctly.
    I have tried the recordings on a different DVD player and TV, with the same result.
    If I play the recordings on my PC, PowerDVD switches to 16:9 automatically.

    I guess I am missing something, but what??

    Cheers
     
  2. DavidES

    DavidES Stunt Coordinator

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    I'm not familiar with dvd burning and I may be incorrect in my thinking, but don't you have to use anamorphic in the burning to have player autoswitch?

    The "Enhanced for widescreen tvs" labeling on commercial DVDs are anamorphic and the player switches on the fly.

    I think that non-anamorphic dvds of a widescreen aspect ratio would show up as a 4:3 LB version on widescreen tvs and I think you had to zoom in to fix.

    I could be wrong but it's just a thought.

    This all that I could find right now about anamorphic here.
     
  3. Steve J Taylor

    Steve J Taylor Auditioning

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    AFAIK, the panny records 16:9 material as anamorphic. It plays back 16:9 fullscreen- no bars (or small bars, but the same as watching it live off-air), as long as 16:9 is selected manually on the TV.

    The movie DVD that I backed-up shows 16:9 in the mpeg data, and 16:9 letterboxed automatic in the .ifo files. The original shows the same. One switches, the other doesn't!

    Cheers
     
  4. Michael Reuben

    Michael Reuben Studio Mogul

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    I'm moving this to Audio/Video Sources. It's a bit beyond a "basic" question. [​IMG]

    M.
     
  5. DavidES

    DavidES Stunt Coordinator

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    Since I really don't know what's going on, you might want to head over to AVS DVD hardware section and hail Stacy Spears, staff member of Secrets, down if you haven't yet. I believe he'll be able to help you out in more detail with the data flags since he does most of the dvd benchmarking there.

    Also since you are recording video and not film like the telecine process does, the 3-2 pulldown flag needs to be off, the flag dealing with framerate be set correctly for 30 fps NTSC or 25 fps PAL since you're from UK (oops just now noticed that), the "progressive frame" flag off if source is interlaced video, and the flag dealing with interlace mode be set like below:

    I|interlacemode 0|1|2
    This sets the sequences picture structure and block encoding type for MPEG2 streams. Setting 0 encodes frame- byframe with support for interlaced video turned off. This is the most efficient option for encoding material that is not interlaced (e.g. movies in PAL 25 frame/sec or NTSC 24 frames/sec in 3:2 pulldown format). However, it produces rotten results for interlaced video material. For such material use I 1 which encodes framebyframe with interlaceadapted motion compensation and block encoding. Alternatively, for highly textured interlaced material with lots of motion you may with to try I 2 which switches to fieldbyfield encoding. This is generally less efficient than framebyframe encoding but will produce more accurate results.
    Note that setting I 1 for noninterlaced material will not do any harm but the encoder will waste a lot of time on calculations that aren't needed.

    That was copied from here which might be of some help to you although it's for another encoder brand.

    I also found this site when google-ing your dvd authoring software for a tutorial but it's a paid-subscription site so...
     
  6. DavidES

    DavidES Stunt Coordinator

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    I'm tending to believe that the tv mode autodetect is looking at the lines in the vertical blanking interval to determine transmitted modes.

    I found that on my player, Lines 21-23 contain a pulse sequence that changes when changing modes. Each mode has a distinct sequence that doesn't change over time. It has a higher amplitude than the closed captioning data that appears to start on line 23

    NTSC VBI data is explained somewhat here but it doesn't say anything about what I found. Scroll down it if interested. PAL VBI data is usually the same except for line locations.
     
  7. Warner

    Warner Agent

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  8. Brian L

    Brian L Cinematographer

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