11 Replies Latest reply: Apr 24, 2007 6:56 AM by Matti Haveri
Stymied again Level 1 Level 1 (0 points)
I am using iMovie to import a series of old videotapes and my question relates to producing the best possible output of these captured tapes from iDVD. So far it seems to me that the original tapes look better than their digital offspring written to DVD. Under Project info there are two encoding options, Best Performance and Best Quality. The help pages state or imply that Best Quality means just that. However that setting also produces smaller files, say 2.6Gb for an 83 minute recording as opposed to 4.6Gb when set to Best Performance. This doesn't seem to make sense as smaller files are presumably more compressed and therefore of lower quality. Can someone explain? What settings should I use?

Thanks.

Mac Pro   Mac OS X (10.4.9)  
  • Klaus1 Level 8 Level 8 (45,955 points)
    Confusing isn't it!

    Best Performance is for projects of less than 60 minutes in length, Best Quality for longer projects. I think we all would like Apple to rephrase that!

    You can read more here:

    http://docs.info.apple.com/article.html?artnum=93629
  • Matti Haveri Level 6 Level 6 (8,840 points)
    Best Performance is for <60 min (single layer DVD) or <120 min (dual layer DVD).

    Best Quality is for <120 min (single layer DVD) or <240 min (dual layer DVD).

    Best Performance may be of slightly better quality than Best Quality in some high-action scenes or other difficult to encode scenes.

    Best Performance seems to use about 7.3 Mb/s (video + audio) for 0-60 minutes. Best Quality seems to use about 5.8 Mb/s for 0-75 minutes and only after this 75 minute point the bitrate starts to steadily decrease so it is about 3.1 Mb/s for 120 minute content.
  • Stymied again Level 1 Level 1 (0 points)
    So if Best Quality uses a lower bitrate perhaps it should be called Less Quality. In principle should a DVD from videotape have the same quality (good, bad or indifferent) as the original? That's what I'm after.
  • Klaus1 Level 8 Level 8 (45,955 points)
    Yes it will.
  • SDMacuser Level 6 Level 6 (13,585 points)
    Just to add to the already excellent advice posted above, please keep in mind that any fast motion (as in high speed sports shots, quickly panning the camera, or even low light situations) will cause iDVD6 to pixelate some scenes. The less movement and the better lit the shot is, the better the results on the final iDVD.

    The help pages state or imply that Best Quality means just that.

    It does mean just that ....for 2 hours of QuickTime playback. If you want THE very best quality then use Best Performance but don't exceed 57 mins. of QT playback.

    Good luck on this.

  • Matti Haveri Level 6 Level 6 (8,840 points)
    So if Best Quality uses a lower bitrate perhaps it should be called Less Quality


    Bitrate isn't everything. A good encoder may well produce better quality with a lower bitrate than another encoder with a higher bitrate. And often good quality takes more time to encode, too.

    I have done some tests and at least with that particular test material I got slightly better quality in a very few high-action scenes with Best Performance.

    But since most of my DVDs are >60 minutes, I always use the Best Quality setting.

    should a DVD from videotape have the same quality (good, bad or indifferent) as the original?


    MPEG encoding compresses data so the quality will always suffer. But usually you don't notice it. It also depends on the input material: difficult to encode scenes include high action, noisy low-light scenes, water, smoke etc.

    With Best Performance or with <75(-90) minutes' Best Quality the iDVD output quality has been OK for me.

    But I'd wish iDVD used compressed audio because uncompressed PCM audio steals way too much bandwidth from video in long (90-120 min) DVDs!
  • Christian Henson Level 1 Level 1 (120 points)
    I'm not happy with how the stuff looks when outputted via iDVD at all and will be surprised that I'm not doing something wrong. The text I have written in on iMovie looks like it's written with a nasty bit of chalk and all the movies are rastorized and at certain points jerky.

    I'm intrigued by compressing the audio, will this help, and which is it to be Best Quality or Performance?

    Thanks for your time.
  • Beverly Maneatis Level 5 Level 5 (7,150 points)
    In principle should a DVD from videotape have the same quality (good, bad or indifferent) as the original?

    If your original tape is VHS, the resultant digital form of it whether DV tape or DVD will be much better since the quality of VHS is not good, and gets worse over time. If your original footage is digital, the quality of the DVD should be the same.
  • Matti Haveri Level 6 Level 6 (8,840 points)
    text


    Text doesn't very well mix with video. Here are some pages describing how to make good-looking titles to your video:

    http://www.kenstone.net/fcphomepage/perfect_titlesphil.html

    http://www.rqs.ca/RollingCredits/faq.php

    compressing the audio, will this help, and which is it to be Best Quality or Performance?


    Neither. iDVD uses only uncompressed PCM audio. But it really matters only with long >75 min projects. Toast uses AC3 audio.

    movies are rastorized and at certain points jerky


    Hmm. Maybe something in the workflow degrades quality? Is the quality OK in iMovie before going to iDVD? I.e. is the quality OK if you output to DV tape and play that to a TV? Or does the quality suffer in the digitizing?
  • Christian Henson Level 1 Level 1 (120 points)
    No the quality is fine when processed in iMovie and I export direct to iDVD (i.e. with all chapter markers etc) and the quality degrades to what I would describe as unsatisfactory.
  • Matti Haveri Level 6 Level 6 (8,840 points)
    Did you set iDVD to use PAL?

    And did you double-check that you used the correct seeting while digitizing (sorry for nagging)? For example I always make sure that I switch the VHS to output s-video via an s-video cable because with the VHS set to composite setting will produce raster artifacts to the digitized video.

    And encoded only a modest length DVD (55-75 min)?

    iDVD isn't the best possible MPEG encoder but I think its quality is decent. Toast's MPEG encoder is somewhat better, so you might also try it, especially if you need Toast for something else, too (like re-authoring MPEG). Several other MPEG encoders are listed here:

    http://www.sjoki.uta.fi/~shmhav/SVCDon_aMacintosh.html#Encode