Should mjpeg and DV video look essentially the same on a tv? More vertical banding problems.

Discussion in 'Professional Video Production' started by Doc, Aug 2, 2005.

  1. Doc

    Doc Guest

    Still trying to get to the bottom of this issue of vertical bands appearing
    in any rendered video that started in DV format transferred by Firewire.

    If you capture the same footage by composite or S-video and then by
    Firewire,
    should they look essentially the same on a consumer TV when rendered for
    playback to tape and/or DVD?

    If you haven't seen my previous post, I find that if I render DV codec video
    for output to tape or DVD, the image is full of these vertical lines or
    bands, maybe 1/16" wide on a "13 TV, all across the image. They're most
    obvious across certain darker/grayer portions of the image.

    I'm including a link to some still image captures off DVD files I made for
    the footage. First some examples based on DV video where you can see the
    banding and then based on mjpg video where you can see there isn't any
    banding.

    The images are approx 25 - 35kb, I didn't want to squeeze the jpeg
    compression too much, to minimize degradation of the image any further. It's
    already gone from avi>DVD>bmp, now a further step to jpeg.

    http://home.mpinet.net/~docsavage20/examples_of_video_banding/index.html


    They're not there with video captured via composite/S-Video and they're also
    not evident when playing the Dig8 camcorder directly to a TV via the
    composite in. However, they are visible when playing a DVD made from the
    footage through the composite connector of the tv.

    Using Pinnacle Studio 9 for input/rendering. Also tried Ulead Video Studio,
    with the same results.

    Someone suggested to turn off "Use Pinnacle DV encoder" in the registry,
    which I tried, but it doesn't seem to make a difference.

    I tried to make both a .wmv and Realmedia file to share on the web but I
    can't seem to make a file that's large enough at a high enough quality that
    you can still see what I'm talking about and the file size of even a few
    seconds of the original DV avi is way bigger than the webspace I have
    available.

    Yes, I can just use the mjpg format but I'd like to be able to use DV
    due to the lower file size and presumably higher quality. Plus, I'd just
    like it to work the way it's supposed to.

    If it makes a difference, using WinXP home. The frame captures were made
    with WinDVD.

    This is really maddening, any help will be sincerely appreciated.
     
    Doc, Aug 2, 2005
    #1
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  2. Doc

    Guest Guest

    | Still trying to get to the bottom of this issue of vertical bands appearing
    | in any rendered video that started in DV format transferred by Firewire.
    |
    | If you capture the same footage by composite or S-video and then by
    | Firewire,
    | should they look essentially the same on a consumer TV when rendered for
    | playback to tape and/or DVD?

    Should.


    | If you haven't seen my previous post, I find that if I render DV codec video
    | for output to tape or DVD, the image is full of these vertical lines or
    | bands, maybe 1/16" wide on a "13 TV, all across the image. They're most
    | obvious across certain darker/grayer portions of the image.

    It could be a bias in the horizontal direction that exists due to some
    not-so-perfect calculations done within each 8x8 block. Are the lines
    spaced exactly 8 pixels apart?


    | I'm including a link to some still image captures off DVD files I made for
    | the footage. First some examples based on DV video where you can see the
    | banding and then based on mjpg video where you can see there isn't any
    | banding.
    |
    | The images are approx 25 - 35kb, I didn't want to squeeze the jpeg
    | compression too much, to minimize degradation of the image any further. It's
    | already gone from avi>DVD>bmp, now a further step to jpeg.
    |
    | http://home.mpinet.net/~docsavage20/examples_of_video_banding/index.html

    Any chance you can go directly to PNG format or BMP format with those frames?


    | They're not there with video captured via composite/S-Video and they're also
    | not evident when playing the Dig8 camcorder directly to a TV via the
    | composite in. However, they are visible when playing a DVD made from the
    | footage through the composite connector of the tv.

    Try converting the format to something different than DV internally before
    trying to go to DVD. That might rule out some trickery the software may
    be trying to do.


    | Using Pinnacle Studio 9 for input/rendering. Also tried Ulead Video Studio,
    | with the same results.
    |
    | Someone suggested to turn off "Use Pinnacle DV encoder" in the registry,
    | which I tried, but it doesn't seem to make a difference.

    It could be the DV decoder in the DVD software.


    | I tried to make both a .wmv and Realmedia file to share on the web but I
    | can't seem to make a file that's large enough at a high enough quality that
    | you can still see what I'm talking about and the file size of even a few
    | seconds of the original DV avi is way bigger than the webspace I have
    | available.

    Maybe one frame would be enough. Can you capture to plain DV (not AVI)?


    | Yes, I can just use the mjpg format but I'd like to be able to use DV
    | due to the lower file size and presumably higher quality. Plus, I'd just
    | like it to work the way it's supposed to.
    |
    | If it makes a difference, using WinXP home. The frame captures were made
    | with WinDVD.
    |
    | This is really maddening, any help will be sincerely appreciated.

    You are encoding as DV/AVI, then transcribing to DVD, then playing the DVD
    back and everywhere that DVD has the banding, but only if DV was the first
    step. That sounds like the DVD authoring software is doing a not so great
    job of decoding the DV/AVI file. Try converting the DV/AVI to MPEG as a
    totally separate step (with software unrelated to the DVD tools) then go to
    DVD with it.
     
    Guest, Aug 2, 2005
    #2
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  3. Doc

    marks542004 Guest

    If the banding is not across the entire image it may be an issue with
    the number of colors available to render the image. This may be
    incorrect color depth set or an over large compression.
     
    marks542004, Aug 2, 2005
    #3
  4. Doc

    Ken Maltby Guest


    You might want to check out "DV Rack" at
    http://www.seriousmagic.com/ They have a trial download.
    That way you can check your source at least, and try
    different codec on the actual camera output.

    Luck;
    Ken
     
    Ken Maltby, Aug 2, 2005
    #4
  5. Doc

    Alex Bird Guest

    I had to really play with my proc amp controls to see the effect, but
    it's definately gone in the mjpeg captures.

    I would say it is block noise, a result of the way the imgae is broken
    down for compression purposes. You shouldn't see it in an image with
    that little detail.
    Your DV codec or mpeg compressor are definately at fault. As there is
    no problem with MJPEG, try to use a different DV codec, you'll find the
    panasonic one online somewhere. Also check you have directx9 properly
    installed.

    Personally I'd increase the contrast too ;o)

    Alex
     
    Alex Bird, Aug 3, 2005
    #5
  6. Doc

    Doc Guest

    How would I determine this? My seat of the pants assessment is that they
    look evenly spaced to me, like a repeating process, perhaps something to do
    with how the image is pieced together that didn't get done quite right? If
    it isn't already obvious, this is an arena in which I'm not technically
    versed.
    frames?

    The BMP's are close to a meg each. I didn't want to burden folks trying to
    help who might be on dialup connection (like me) and upon re-examing them, I
    don't think the problem is any more visible than it is on the jpeg's I
    put up.

    You mean take the DV, go into say Virtualdub and save under a different
    compression scheme such as PICmjpg, Indeo, MPEG-4, Microsoft Video etc.?
    Tried it, it's still there. It's in the original DV/Avi file.
    It's there in the original DV file, even before conversion to DVD. You can
    see it really well when rendering for output to tape and then running the
    composite out to the tv, as it comes across more distinctly on a TV screen
    than on a computer screen, but when watching the original, raw DV/avi file
    in Virtualdub, I can make out the lines. However if I capture in mjpeg
    format instead of DV, then they're not there. Play a digital tape to TV
    directly, they're not there. The culprit appears to be the DV capture
    process to the h/d.

    Um, not sure how to do that, or how to take just one frame of it. I thought
    all captures were avi? How would one capture directly as DV?

    I could be wrong, but I don't think one frame would show you more than the
    images I put up already. You really have to see the video in motion to see
    it really clearly. I had to hunt around for these frames to find some that
    you could see it to any degree in a still image. For the most part, all you
    see in one frame is a bunch of grainy pixels, but when the image moves, you
    can see it.

    It's there in the original DV/Avi file, even before the DVD step.
     
    Doc, Aug 3, 2005
    #6
  7. Doc

    Doc Guest

    It's across the entire image, it's just not readily visible in a still
    image. You really have to see it in motion, then it becomes much more
    apparent. I just happened to find that you could get a glimpse of it in part
    of these particular frames due to the tone of the image.

    It just seems to get washed out by low resolution in the streaming files I
    created, so there wasn't much point in posting them.
     
    Doc, Aug 3, 2005
    #7
  8. Doc

    Doc Guest

    I appreciate it. I tweaked the brightness/contrast in these particular
    shots in Paintshop Pro to bring out the artifacts more. The video doesn't
    look like these.

    I have the Panasonic DV codec on my computer, how do I know whether that's
    what I'm using? I have DirectX 9, how do I know if it's properly installed?
    I've seen nothing telling me otherwise.
     
    Doc, Aug 3, 2005
    #8
  9. Doc

    Ken Maltby Guest

    To check out DirectX, go to the "Control Panel" follow the
    clues from there.

    The DSFMgr from www.softella.com is perhaps the easiest
    way to deal with codec and filters.

    Luck;
    Ken
     
    Ken Maltby, Aug 3, 2005
    #9
  10. Doc

    Guest Guest

    |> It could be a bias in the horizontal direction that exists due to some
    |> not-so-perfect calculations done within each 8x8 block. Are the lines
    |> spaced exactly 8 pixels apart?
    |
    | How would I determine this? My seat of the pants assessment is that they
    | look evenly spaced to me, like a repeating process, perhaps something to do
    | with how the image is pieced together that didn't get done quite right? If
    | it isn't already obvious, this is an arena in which I'm not technically
    | versed.

    They look even to me, too. But I'm not going to try much more with
    it due to the reprocessing into JPEG to make the still frames.


    |> Any chance you can go directly to PNG format or BMP format with those
    | frames?
    |
    | The BMP's are close to a meg each. I didn't want to burden folks trying to
    | help who might be on dialup connection (like me) and upon re-examing them, I
    | don't think the problem is any more visible than it is on the jpeg's I
    | put up.

    I would not expect it to be more visible, just easier to analyze.
    The PNG's should be smaller by using a lossless compression.

    If you have Linux you could run my true-color GIF software and
    make GIF files of them.


    |> Try converting the format to something different than DV internally before
    |> trying to go to DVD. That might rule out some trickery the software may
    |> be trying to do.
    |
    | You mean take the DV, go into say Virtualdub and save under a different
    | compression scheme such as PICmjpg, Indeo, MPEG-4, Microsoft Video etc.?
    | Tried it, it's still there. It's in the original DV/Avi file.

    So that suggest the DV encoder is the culprit.


    | It's there in the original DV file, even before conversion to DVD. You can
    | see it really well when rendering for output to tape and then running the
    | composite out to the tv, as it comes across more distinctly on a TV screen
    | than on a computer screen, but when watching the original, raw DV/avi file
    | in Virtualdub, I can make out the lines. However if I capture in mjpeg
    | format instead of DV, then they're not there. Play a digital tape to TV
    | directly, they're not there. The culprit appears to be the DV capture
    | process to the h/d.

    Then some unexpected processing is involved between the digital tape and
    the DV transfer that causes it to go through re-compression or such.
    If that's a DV tape, it shoyldn't need to, but it may simple be doing
    so for unknown design reasons.


    |> | I tried to make both a .wmv and Realmedia file to share on the web but I
    |> | can't seem to make a file that's large enough at a high enough quality
    | that
    |> | you can still see what I'm talking about and the file size of even a few
    |> | seconds of the original DV avi is way bigger than the webspace I have
    |> | available.
    |>
    |> Maybe one frame would be enough. Can you capture to plain DV (not AVI)?
    |
    | Um, not sure how to do that, or how to take just one frame of it. I thought
    | all captures were avi? How would one capture directly as DV?

    DV is itself a complete format as well as a codec format. It even include
    audio. AVI is a generalized format that supports many codecs and DV is one
    of the codecs. AVI includes audio. AVI/DV duplicates the audio, or so I
    am told.

    If you capture software does not have DV as a format choice, then I guess
    you cannot capture as DV. I'll look to see if I can find software that will
    strip just DV from AVI/DV.



    | I could be wrong, but I don't think one frame would show you more than the
    | images I put up already. You really have to see the video in motion to see
    | it really clearly. I had to hunt around for these frames to find some that
    | you could see it to any degree in a still image. For the most part, all you
    | see in one frame is a bunch of grainy pixels, but when the image moves, you
    | can see it.

    What I am wanting is to eliminate as much post-processing. I want to see
    just how the DV's compressed data gets decoded by other DV decoders, for
    example.


    |> You are encoding as DV/AVI, then transcribing to DVD, then playing the DVD
    |> back and everywhere that DVD has the banding, but only if DV was the first
    |> step. That sounds like the DVD authoring software is doing a not so great
    |> job of decoding the DV/AVI file.
    |
    | It's there in the original DV/Avi file, even before the DVD step.

    OK, I misunderstood and thought it was only showing up in DVDs. If it
    is there before the DVD, then let's just leave the DVD out of it and
    see what can be figured from there. I don't use Windows and I need to
    find some tools for AVI on Linux.

    BTW, once a video is stored in DV format, selecting frames is quite
    easy because for NTSC, each frame is exactly 1200000 bytes (144000 for
    PAL). I can slice out exactly one frame without doing any video
    processing by just selecting which frame number I want (zero starting
    reference), multiply by 120000, and copy the next 120000 bytes.
     
    Guest, Aug 3, 2005
    #10
  11. Doc

    Alex Bird Guest

    I'm not an expert, those were just things I would have fiddled with
    first.
    I've just had a thought (don't laugh). MJPEG uses square pixels, the
    others not (i.e. 768x576 vs 720x576 pal). The difference could lie
    somewhere in the resampling...

    Alex
     
    Alex Bird, Aug 3, 2005
    #11
  12. Doc

    AnthonyR Guest

    I don't know if it's my imagination or not but the aspect ratio of the top
    pics looks skinner than the bottom captures to me.
    Look at the door for example its wider in the bottom, maybe the lines are
    some type of artifact because the image is being squeezed
    horizontally somehow, square pixels as oppossed to non square etc.. just a
    thought.
    AnthonyR
     
    AnthonyR, Aug 5, 2005
    #12
  13. I looks like artifacts from the MPEG2-codec. They usually tend to go funny
    on areas which have largely the same colour. I would re-render them with a
    decent MPEG-2 renderer. It might be Ulead and Pinnacle use the same one.
    Try the CCE-one. It has a gazillion parameters, where you can tune per
    frame, or time period a huge amount of parameters for your final output.

    cheers

    -martin-
     
    Martin Heffels, Aug 5, 2005
    #13
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