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  1. Member
    Join Date
    Sep 2009
    Location
    Singapore
    Search Comp PM
    Hi,
    I'm volunteering for a non-profit organisation that's looking to put an ad on TV.

    As they don't have the funds to make the ad, we are planning to get the ad made through an online competition.
    I'm trying to figure out the optimum way to conserve bandwidth, but still end up with a good quality, professional looking end product. (we would like to broadcast on HDTV if possible, but that may be too ambitious for our infrastructure).

    The competition will be two staged - first people will send in "source material", which we will put on our website.
    After that, people can download the source material, mash it up, add their own, and upload a 30 second commercial for the competition.

    Getting them to upload and download in DV format is not practical because that works out at ~100MB per submission.

    But also if the first stage is uploaded in DVD or lower quality - there will be ugly artifacts when it's re-encoded for the second round.

    I was thinking that using a more compressed format at a high resolution and bit rate might be the answer. Maybe something like MP4 at 10 Mbps?

    I know a lot of you here would have done experiments with video quality in converting, so I was wondering if you had suggestions for this, and particularly what would be a safe bitrate for initial postings that could be mashed up without introduction of artifacts that would be disruptive for viewing on TV.

    Cheers for any help.
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  2. Interlaced encoding efficiency is lower than for progressive, but if this is for broadcast, you will probably want to keep everything interlaced at all stages (submissions, website hosting for the downloads, and re-submissions for final product).

    You may want to set up guidelines/rules for source content submissions to keep consistency (it would be harder to do a project with mixed sources, HDV, DV, TFF interlaced, BFF interlaced, progressive , PAL, NTSC spec, etc....)

    While h.264 offers the best compression ratio, interlaced encoding efficiency of the freeware x264 encoder is not optimized, and is more difficult to edit than, say MPEG2 - especially if it's HD. Having said that I would still use h.264 if you were to set a cap of 10Mbps. Using anything else at that bitrate for HD resolution would not be feasible

    It's difficult to use a set bitrate cap, because it depends on content complexity (e.g. content with high motion and detail will require more bitrate than still shots or low complexity content). Clips that require more will look bad, and clips that don't will look too good in comparison. There will be a quality stepping which will look bad when the clips are put together. One way to get around this might be to use CRF or constant quality encoding.
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  3. If users are going to edit in their program and export to MPEG-2 at a low or medium quality level or bitrate, you're not going to end up with a very nice result anyway. You may want to customize a package containing x264 for users, so it uses the settings you want (e.g. CRF, presets). Then ask users to export to lossless and use the packaged x264 to encode it.

    Alternatively, just ask them to upload at maximum quality in any of a few specified formats and a specific resolution.

    If you're doing it for any Singaporean nonprofit, I'd be glad to offer any assistance that I can (possibly webspace).

    P.S. x264 is a H.264 encoder, and H.264 is one of the video formats that can be stored in MP4 files.
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  4. Ideally you would keep the original formats. And if hosting bandwidth is an issue, you can explore free file hosting sites, such as megaupload.com , mediafire.com , many others... There maybe some better free hosts in your region
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