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  1. Hi guys,

    It's been long time that i din't have much chance to work on video editing. Once in a while, now I have a problem would like to have some suggestions from you.

    I have a source video, specs as follows:
    1280x720, 16:9, 23.976 fps, bit rate 13.6 Mbps

    I would need to have the output as follows:

    WMV9 CBR 2-Pass 2MBps transfer rate w/ 64kbps, 44kHz stereo output
    720X405 output for 16:9 Aspect Ratio


    Are these outputs could be done in Premiere CS4?


    I tried to work on
    720x405, 16:9 but Premiere said that the pixel ratio is invalid. I guess because it was not an even number. So how should I solve these problems? Is there any suggestions about project setting and output settings i need to change?

    Thank you in advance for all your helps here.
    Last edited by umforrest; 5th Jul 2010 at 20:25.
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  2. Originally Posted by umforrest View Post
    I tried to work on 720x405, 16:9 but Premiere said that the pixel ratio is invalid. I guess because it was not an even number. So how should I solve these problems?
    Do what it says and use an even number. YV12 codecs will not allow odd frame sizes.
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  4. That means there's no other way to get 720x405 16:9 from Premiere (CS4)? Is there any software can do this?
    Last edited by umforrest; 5th Jul 2010 at 20:25.
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  5. You cannot get 720x405 with any program when using a codec that encodes in YV12. Use 720x404, or even better, 720x400 (mod 16) instead. You won't be able to see the small AR error.
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  6. Originally Posted by jagabo View Post
    You cannot get 720x405 with any program when using a codec that encodes in YV12. Use 720x404, or even better, 720x400 (mod 16) instead. You won't be able to see the small AR error.
    Thank you very much for your help here, jakobo. I understand that YV12 is a codec, correct? If we change the codec, that means we will be able to get 720x405? 16:9? And could you explain a bit more about Mod 16?

    My source video is 1280x720, 16:9. So I think it's possible to make it as 720x405, 16:9, same aspect ratio. Is there anything wrong with my assumption? I tried with Premiere but didn't work as mentioned in my original post. Today i tried with Vegas but whenever i put 720x405, it will automatically change to 720x408.
    Last edited by umforrest; 5th Jul 2010 at 20:29.
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    Not sure why you're so determined to get 405. Do you think you will notice the 0.25% error in the aspect ratio if you encode to 704?
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  8. Member edDV's Avatar
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    Originally Posted by umforrest View Post
    Originally Posted by jagabo View Post
    You cannot get 720x405 with any program when using a codec that encodes in YV12. Use 720x404, or even better, 720x400 (mod 16) instead. You won't be able to see the small AR error.
    Thank you very much for your help here, jakobo. Unfortunately, I don't quite understand what you mentioned about YV12. , is it a codec? If we change the codec, that means we will be able to get 720x405? 16:9? I also don't have much idea about mod16 as well as "small AR error. Could you kindly help clarify a little bit more?

    My original that was that my source video is 1280x720, 16:9. So I think it's possible to make it as 720x405, 16:9, same aspect ratio. Is there anything wrong with my assumption? I tried with Premiere but didn't work as mentioned in my original post. Today i tried with Vegas but whenever i put 720x405, it will automatically change to 720x408.
    You could only do it for uncompressed 4:2:2 video which I assume you don't want. Figure ~160 GB/hr.

    MPeg compression schemes (Mpeg2, divx, xvid, h.264) appropriate for DVD, DVDR or BD divide the picture into 16x16 pixel blocks using YV12 pixel components.
    http://en.wikipedia.org/wiki/YUV

    720/16 = 45
    400/16 = 25

    So think of it as a 45 block x 25 block frame. To fit your 16:9 image into that size, you need to compromise aspect ratio slightly or accept a small amount of vertical cropping. Or, if you go to 45x26 blocks (720x416), you would accept some mild letterbox.

    BTW, if you want this video to be MPeg2 compliant for DVD, you would use non-square pixels at 720x576 (45x36 blocks) and use a pixel aspect ratio (PAR) of 1.4568. Premiere presets usually assume you want a spec DVD.

    See "What is DVD?" https://www.videohelp.com/dvd
    Last edited by edDV; 2nd Jul 2010 at 14:42.
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  9. Originally Posted by umforrest View Post
    Unfortunately, I don't quite understand what you mentioned about YV12. , is it a codec?
    YV12 refers to a specific arrangement of YUV 4:2:0 chroma subsampling. In short, YV12 stores color information at half (both dimensions) the resolution of the grayscale image. A 720x480 frame in YV12 consists of a 720x480 grayscale channel (Y), and two 360x240 chroma (color) channels (U and V).

    http://fourcc.org/yuv.php#YV12

    A 405 line tall frame would require 202.5 line chroma channels -- you can't have half pixels. Any program or codec that works in YV12 cannot use odd frame sizes.

    Originally Posted by umforrest View Post
    If we change the codec, that means we will be able to get 720x405?
    Maybe. Most high compression codecs use YV12. There are a few that use YUV 4:2:2 subsampling which would allow for odd frame heights but still require even frame widths. For example HuffYUV. It also depends on whether Premiere is working in YV12 or not.

    Originally Posted by umforrest View Post
    I also don't have much idea about mod16
    Mod16 refers to a frame size that is an integer multiple of 16 (16, 32, 48, 64,... 400, 416...). The first thing MPEG family codecs do is break the frame up into 16x16 pixel blocks. Those blocks are further broken down into 8x8 pixel blocks for processing. So they work best when the frame size is an inter multiple of 8 or 16. Some don't even allow less than mod16 or mod8. Those that do are less efficient when they do because they are forced to use special handling at the edges.


    Originally Posted by umforrest View Post
    as well as "small AR error".
    AR = Aspect Ratio. Using a 720x404 frame instead of 720x405 would give you a frame that was not quite 16:9. It is off by about one quarter of one percent. You cannot see that small an error.
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  10. Thank you Jagobe, edDV and KBee for all your clarifications and valuable suggestions. I very much appreciate it and it really inspires me. I now would like to learn more about video production in depth and would also like to share any knowledge I may have whenever I have an opportunity.

    Thank you again, guys.
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