Easiest 1080i to 480p MPEG-2 Conversion

Discussion in 'Digital Video' started by Heb1228, Oct 2, 2009.

  1. Heb1228 macrumors 68020


    Feb 3, 2004
    Virginia Beach, VA
    I'm using an EyeTV to capture HD footage - this channel broadcasts in 1080i and the EyeTV captures the original MPEG-2 stream - so its lossless in quality. I'm saving the original files and all for future use when I can work with HD footage more easily, but for now, I'd like to make a high quality DVD from the footage.

    I'm assuming (but willing to be corrected) that 480p is the highest quality that will play on a traditional dvd player. So what is the best way to get the 1080i footage down to 480p?

    If possible, I'd like to avoid having to transcode to ProRes or AIC and then back to mpeg 2. I've tried to figure out how to do this with Mpeg Streamclip, ffmpegx, and compressor, but haven't been able to figure it out so far.

    Anyone got any help they can give me on this?

    I'm thinking if something would downsize to 540p, that would take care of the interlacing problem, simply by taking half the lines out.

    The original footage is 1920 (1440 stretched, I believe), by 1080, interlaced.

    I guess I need to get from that to 720x480 progressive. I have Windows 7 installed via bootcamp so if no Mac tools can do this is there anything on the dark (Windows) side?
  2. MisterMe macrumors G4


    Jul 17, 2002
    Your Mac shipped with this program called iMovie and another one called iDVD?
  3. clancemasterj macrumors regular


    Jan 31, 2007
    Somewhere outside of time.
    mpegstreamclip is something I swear by. You can transcode anything to everything. http://www.squared5.com

    Maybe I should read the entire post....

    Did you try just throwing it into dvd studio pro? Just use the standard def setting and bump the bitrate to 9-14mbs...
  4. Heb1228 thread starter macrumors 68020


    Feb 3, 2004
    Virginia Beach, VA
    I'd be happy to use iMovie if it imported MPEG-2 footage properly. I also mentioned I wanted to avoid transoding to an intermediate format, which iMovie would do IF IT COULD import that footage, which it can't.

    I'd be happy to use iDVD except, as the title of my post says, I'd like the DVD to be in 480p quality - which is not possible in iDVD.

    Next time you want to get smart with someone, you might want to make sure you know what you're talking about. When you have something to add that might actually help, feel free to post again.

    clance, I didn't try DVDSP, but I wasn't aware it would import MPEG-2 footage either, I'll check it out to see if that's possible.
  5. huntercr macrumors 65816

    Jun 6, 2006
    It can't import MPEG2 directly... Toast can, I believe, but it might only be if you're keeping the same resolution.

    I think you're wanting something that just isn't possible. If you had something on Windows that did this for you it just kept the intermediate trnascoding behind the curtain. It's a fact that re-encoding has to occur since you're going from 1080i to 480p.
    The time to reencode into AIC is absolutely minimal compared to what it will take to encode your MPEG2 in 480p ( minutes vs. hours )
    Don't get hung up on the extra step.

    Use MPEGStream to export to Quicktime with AIC codec. You could choose to down size the video at this stage or later in the process ( YMMV ) to SD NTSC 720x480

    Then load it into iMovie or Final Cut if you want to do editing, or just drag the whole thing to iDVD or DVDSP. No, iDVD won't do progressive, but if you leave the signal interlaced, your loss will be minimal. ( especially compared with the loss of going down from 1080i )

    Hope this helps.
  6. LethalWolfe macrumors G3


    Jan 11, 2002
    Los Angeles
    Don't worry about trying to make the footage progressive. Your source material is 1080i @ 29.97fps and your end product is 480i at 29.97fps (DVD's will do 480p but only at 23.98fps). And don't worry about going to a good intermediate codec like ProRes (not HQ).

  7. Heb1228 thread starter macrumors 68020


    Feb 3, 2004
    Virginia Beach, VA
    Ahh this is good info... I didn't realize the frame rate had any effect on this process. I've got a good way for working with the footage in SD already, so I guess I'll just stick with that until I get a blu-ray burner.
  8. fpnc macrumors 68000

    Oct 30, 2002
    San Diego, CA
    You absolutely and positively need to deinterlace that 1080i or you will likely get random scaling and interlacing artifacts when you try to produce your final standard definition output.

    Further, when you talk about interlacing you're really talking about two things, the playback/capture device or mechanism and the existence of a temporal (time) difference between alternate scan lines in the source or output video. What this means is that you can "deinterlace" a video and still play it back on an interlaced device (just as you can view interlaced material on a progressive device).

    What you should really be concerned about is the temporal difference in the alternate scan lines (that's what produces the combing effect or artifacts when you view interlaced material on a progressive device like a computer display). Further, you NEVER want to rescale interlaced material unless the scaling is an exact even multiple of the original source or you deinterlace BEFORE you rescale the content (if you don't do this you may end up with very odd and distracting combing effects and/or artifacts in the final video). Some software may handle this automatically (or have options to do so), but you need to be sure about this or the results could be pretty ugly.

    Probably the best way to get what you want is to decimate the 1080i content to 960x540 (downscale to 1/2) which if done correctly will remove either the odd or even scan lines and produce content that has no interlacing artifacts. From that point you can scale down to anything that you want and the results should be about as good as you can get. You also want to keep the output at 29.97fps as it is actually pretty hard to get good results when you go from 29.97fps to 23.97fps or 24fps (because to get those lower frame rates you will either have to drop frames -- which may produce jerky motion -- or blend frames which will affect the sharpness of the final result).

    The other option (rather than the decimation) is to use a quality deinterlacer and then scale that intermediate to the standard definition resolution.

    You may be able to find a workflow or utility to do the decimation or deinterlacing and scaling in one session/step if you are worried about making too many intermediate versions of the original.

    In any case, you definitely want to do something to remove the interlacing artifacts before you convert the video to standard definition resolutions.

    It's also possible that the original content was shot at 24fps and telecined to produce the 29.97fps broadcast. If this is the case (and it's actually likely if the source material was from film) then ideally what you'd want to do is an inverse telecine to convert the broadcast back to its original progressive, 24fps format. Unfortunately, it's practically impossible to do a quality inverse telecine if there are any cadence breaks in the original telecine process (and there usually are). If you don't understand the latter then don't sweat it, what this just means is that even if the broadcast source was telecined you'll probably do no better with an inverse telecine than with the process I first described above (i.e. decimate and rescale or deinterlace and rescale).

    I also agree that you shouldn't worry too much about doing an intermediate conversion to some nearly lossless format and then working from that to produce your final DVD.

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