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Thread: 24p DVD... Question

  1. #1
    Administrator Lunchbox's Avatar
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    Default 24p DVD... Question

    I have to admit I never pay much attention in the process of creating 24p footage on DVD. Recently I start shooting 24p with DSLR. Now it's time to output to DVD.

    Correct me if I'm wrong. For my understanding, we can work with 24p footage on DVD by either method.

    (1) Encode to MPEG-2 with 2-3 pulldown (hard telecine) added. The resulting footage is 29.97.

    (2) Encode to 23.976fps MPEG-2. Author the DVD. During playback, depends on the capability of DVD player, some can insert the 2:3 pulldown on the fly. For those progressive DVD players connect to HDTV, it will play back the pure 24p.

    Is it true?

    Or (3) is all 24p DVD encoded like in (1), then the DVD player remove pulldowns on the fly during playback?

    Thanks

  2. #2
    ...formerly known as 'drapeama' Marc-Alexandre Drapeau's Avatar
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    Taky, from what I understand of 24p DVDs, DVD will always output as 60p when progressive output is selected, well on my Sony Bluray though. On charlie's LG BD player, it still reads 60p on the TV as the input. So the players read 23.976fps and add the pulldown flag to it for compliancy, no matter what's the players output, connection or whatever. Only HD content can be output as 24p. I wouldn't bother much about that, if one client comes back with a non playable DVD, suggest him to upgrade his device because it'll be 10years old +. 23.976fps is part of the NTSC standard, and part of the DVD specs too...
    That being said, since I bought my HV40, I never rendered 24p+pulldown and I never had any problems on many DVD players. I would simply render as 23.976 fps and it should be fine.
    I DO IT BECAUSE I CAN. I CAN BECAUSE I WANT TO. I WANT TO BECAUSE YOU SAID I COULDN'T.

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    Administrator Lunchbox's Avatar
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    Marc, I think there're a few things wrong from your statement. Hope you don't mind.

    DVD NTSC is always 60i. 60p and 24p is are not part of the standard NTSC DVD spec.

    After doing a bunch of research, I think what 24p DVD is, the encoder insert the 2:3 pulldown flag (not the frame) to the 24p stream (23.976) to signal the DVD player it is 29.976fps stream. It isn't the hard telecine process (as in 24p in HV20) those pulldowns are physically inserted into the stream. During playback, regular DVD player will insert the pulldown frames from the signaling of the flag. For those new progressive DVD, it will output the pure 24p stream to progressive TV display.

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    Senior Member EvilBastardProductions's Avatar
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    Not sure how it would go with NTSC, but I shoot/edit/export everything in 24p with Premier Pro, dump that in Encore (PAL) and Encore takes care of it all. Done a bunch of client DVDs this way, no hassles.
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    Administrator Lunchbox's Avatar
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    Did you check in Encore project pane that your video showing "Don't Transcode" or "Untranscoded" ?

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    Senior Member EvilBastardProductions's Avatar
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    From memory, all untranscoded until building the actual dvd iso. Pretty much just used the default settings as tbh, im lazy lol. I'm guessing it just duplicated a frame every second to make it up to 25i. Whatever it did, I tested it on the computer against a DV24p render and looked exactly the same.
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    Administrator Lunchbox's Avatar
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    It's best to avoid "untrancoded" status avoid another generation loss of quality. If you export from timeline in premiere to Adobe Media Encoder picking MPEG-2 DVD presets, after loading to Encore, it should say "Don't transcode". Otherwise, Encode will transcode for a second time which is not necessary.

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    Senior Member EvilBastardProductions's Avatar
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    Huh never even thought of that. Glad you picked up on it bro, cheers.
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    ...formerly known as 'drapeama' Marc-Alexandre Drapeau's Avatar
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    Quote Originally Posted by Lunchbox View Post
    Marc, I think there're a few things wrong from your statement. Hope you don't mind.
    DVD NTSC is always 60i. 60p and 24p is are not part of the standard NTSC DVD spec.
    After doing a bunch of research, I think what 24p DVD is, the encoder insert the 2:3 pulldown flag (not the frame) to the 24p stream (23.976) to signal the DVD player it is 29.976fps stream. It isn't the hard telecine process (as in 24p in HV20) those pulldowns are physically inserted into the stream. During playback, regular DVD player will insert the pulldown frames from the signaling of the flag. For those new progressive DVD, it will output the pure 24p stream to progressive TV display.
    1) Of course not, re-reading myself again and I think I didn't wrote it clearly last time: because you're right!. Some interesting reading on VideoHelp.com/DVD and here too.
    2) DVD specs is 29.976fps but it is possible to play 23.976fps DVDs, as the DVD player reads the video and automatically adds the pulldown for the "missing" frames in order to read the 29.976fps "compliant" NTSC format.
    3) I don't think it's the encoder that adds those flags because it would works the same for HD content, right? And HD players would also reads the 23.976fps as 29.976fps too. I think. I personally think it's the player that "decodes" the video streams and adds the pulldown flags "on-the-fly". That's what I think from my own experiences, but I might be wrong.
    Here's some infos I've read on wikipedia:
    Quote Originally Posted by wikipedia - 24p
    Displaying 24p material With NTSC equipment, it is impossible to display a 24p signal directly as the monitors only support the 60i framerate. Hence, pulldown must be added to the 24p material to be displayed. Most editing systems will either add 3:2 pulldown or 2:2:2:4 pulldown. In the 2:2:2:4 pulldown scheme, used as a choice primarily by Apple's Final Cut Pro, every fourth frame is repeated. This scheme is easier for slower hardware to implement as it requires less processing.
    In HD production, the HD-SDI interface supports the 24p framerate in addition to the 60i and 50i framerates. Many HD monitors are able to receive a 24p signal (not a 60i signal with pulldown added) and can display the 24p material directly.
    For end-user viewing of HD material, many digital formats are offering 24p support. Computer formats such as Windows Media, Quicktime, and Real video can play 24p video directly on a computer monitor.
    Quote Originally Posted by Lunchbox View Post
    It's best to avoid "untrancoded" status avoid another generation loss of quality.
    By that you simply have to calculate your "peaks" in your video (maximum bitrate) and calculate the audio (2ch 192kbps / 6ch 448kbps) and substract both values from 10080kbps (maximum muxed bitrate allowed). Your best bet is to allow yourself 448+192 for 2 audio tracks (640kbps) and some room just to be sure: 10080 - 640 = 9440. So let's render your video with a maximum bitrate of 9400kbps (according the length of the video at that bitrate fits on a DVD5 or DVD9).
    I DO IT BECAUSE I CAN. I CAN BECAUSE I WANT TO. I WANT TO BECAUSE YOU SAID I COULDN'T.

  10. #10
    Administrator Lunchbox's Avatar
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    DVD spec is NTSC 29.97 fps. That's why a good encoder will add pulldown flags (not frames) to the 23.976 frames to tell the player to insert the pulldown frames during playback.

    However, for Bluray, 23.976fps is part of the specifications. There is no need to insert flags.

    When I encode videos for DVD and Bluray, I encode each video to 3 to 4 different bitrate. Then I mix and match the output files to fill the 4.7GB DVD, or DVD-9 or 25GB for BluRay.

    For example, for wedding ceremony chapter, it's least watch and less motion. I will pick a lower bit rate encoded files to save the disc size for a more important and frequent watched video such as the highlights video. You can read more in my blog

    http://lacoloronline.com/blog/?10176...luRay-Workflow

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