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Forums Compression Techniques HD to muxed mpeg2 – please help!

  • HD to muxed mpeg2 – please help!

  • David Telling

    February 10, 2006 at 1:23 am

    I am having a very difficult time finding a solution to this situation and time is running out on me.

    I work in FCP 5 and am now creating presentations in HD 720P (1280 x 720)

    Compression using H.264 for computer playback has been very successful, but I am faced with a need to supply a client with either a HD.wmv file or 1280 x 720 muxed. mpg file for playback on a PC within a program called SCALA (which does not like Quicktime!!)
    These presentations are going to be played back full screen on large 63″ plasmas.

    With previous SD presentations within this work flow, I have saved self contained files out of FCP – exported an .m2v (video) and .aiff (audio) file out of Quicktime Pro and then muxed them together into one .mpg file using BitVice Helper – fantastic!
    However now I’ve moved to HD presentations things have changed: Now I’m in Tiger, QT 7 Pro doesn’t apparently have the mpeg 2 export . So, I’ve turned to Compressor and have tried following a similar work flow. I’ve used the HD DVD mpeg 2 default (1280 x 720) as a starting setting, and reduced the bit rate down to 10mb/sec for desktop playback. I’ve also exported the related .aif file at the same time.

    The resulting .m2v file looks great within Quicktime player and the .aif file plays separately without a hitch – but when I now try to mux them in BitVice Helper (after creating the necessary .mp2 audio file) BitVice muxes approx 8 seconds of the presentation but gives data warnings and then a final error saying that there are too many dropped frames and stops processing the files.

    Is this problem simply due to the fact that BitVice Helper is not able to process anything larger than 720×480 and 9Mb/sec?? If so, is there any other program that could Mux these files successfully.

    I’ve used Flip4Mac to try and create .wmv files as an alternative, but they just do not come close to the quality of H.264 or even the mpeg 2 files.

    Thank you for any help you can offer me. I really have tried hard to resolve this but have come to a dead end.

    I appreciate your assistance.

  • Charles Simonson

    February 10, 2006 at 6:22 am

    On BitVice Helper, I would suggest two things. First, convert the AIFF to WAV with QT Pro and see if that helps. If not, then it likely does have something to do the frame size. Could be BitVice Helper looks for a certain GOP structure, and if you’re using 720p60, then it may not support that. I don’t use BitVice Helper too much these days, as there is a newer program that generally handles more formats. This app is MPEG StreamClip. Download it and then try and save a program stream (Convert to MPEG). If the audio and video files have the same name, then MPEG StreamClip will usually recognize both and automatically combine the two when you open up the video stream in the app. If it doesn’t automatically do so, then you will need to just select the audio and video tracks at the same time and bring them in to MPEG StreamClip.

    Most computers can easily handle up to 18Mbps these days for MPEG-2, but if 10Mbps looks good then I would stick to it. Per your problems with Flip4Mac, I find that pretty surprising. I have some issues with it, in that it is slow and the color conversion that it uses isn’t perfect (more a by-product of having to use QT though), but the overall quality of the encode is generally considered quite good. Apple’s H.264 and MPEG-2 encoders are quite good these days (although neither are the best), but I don’t think either is that much better or worse than the F4M encoder in terms of core quality at each’s best settings.

  • David Telling

    February 10, 2006 at 7:24 am

    Thank you so much for getting back to me, and so quickly. I did indeed try MPEG StreamClip and it seemed to work flawlessly on my test clips, so it seems you’ve given me a potential solution to my problem.

    I’m not sure why I’ve had a problem with Flip4Mac. Perhaps it’s just the type of material I am working with (the content is quite dark, with a lot of moving, composited images and transitions) but it seems to produce a good deal of “blockiness” and discoloration (towards green) – no matter what settings I use. I have had conversations with the Flip4Mac moderator and he has seen some of the same problems. I’m sure it will be much better on other materials.

    Again, I truly appreciate your help. I will finally be able to sleep tonight!

  • Craig Seeman

    February 10, 2006 at 6:00 pm

    Hi David,

    Post your complete work flow if you can. I’ve used Flip4Mac with DVCProHD and I know others who’ve used HDCAM source to produce 720p WMVHD files without issue. A few have reported blockiness on dissolves with HDV source. I can’t help but think it’s how WMV export handles heavily compressed HDV.

    Charles have you tested Flip4Mac with HDV source?

    My own recommendation would be to get out of HDV on import/capture. Upconvert to DVCProHD on import to get away from the heavily compressed HDV GOP structure. I suspect dissolves (as well as keys) will survive much better.

    David, I’d like to see an HDV clip wrapped in mov (export from FCP as Quicktime Movie Self contained). If you email me I’ll give you FTP info. Streamclip (I use it also) may get you through this deadline but I’d like to examine the HDV issue closely.

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