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  • john.vk5kg
    Posts: 2
    Joined: Dec 6th, 2010, 09:00
    My iMovie 9 Video
    Hi there - this is my first post! Recently I completed quite a long movie of a recent overseas holiday shot in 16:9 HD on a Panasonic TM-300 camera, edited firstly in iMovie 8 and completed in iMovie 9. I live in a PAL country so my native frame rate is 25fps. I want to show my movie in HD so that rules out a standard DVD (although I have made one successfully "for safety"!) I decided not to get a BluRay recorder/player yet until the prices come down a bit. So I decided to upload my movie to my TiVo (which has an external 1 TByte drive giving me lots of storage space). Using iMovie 9 I "shared" my movie using "Export Movie..." selecting the highest reset resolution namely HD 1080P. This produced a .mov which plays smoothly both on a Mac and on a Windows XP computer. But when I send the movie to my HD TiVo using "TiVo Desktop", the resulting movie while good is not as "smooth" as on the computer. Specifically, on very slow moving scenes all looks well; but on rapid movement of the subject or on pans and zooms the picture "staggers". If I use the TiVo's ability to play in slow motion, I see even movement between frames for 4 frames but the next frame is a repeat of the fourth frame in a sequence that runs "1, 2, 3, 4, 4, 1, 2, 3, 4, 4" etc. Again when the original .mov is examined on either Mac or Windows the movement does not show this "stagger"; instead it looks like "1, 2, 3, 4, 1, 2, 3, 4, etc. [I am using "1, 2, 3, 4," merely as a way to describe what can be seen; it has no technical meaning apart from that - ie it bears no relation to the PAL field sequence]. 1. My first question then is has anyone else seen an effect such as this when transferring a movie from a computer to a PVR such as Tivo? 2. Can you make any suggestions as to appropriate codec settings for storage on TiVo preserving HD quality playback?
    Reply
  • Rounik Admin
    Posts: 8713
    Joined: Dec 16th, 2006, 08:13
    Re: My iMovie 9 Video
    Hi john.vk5g Welcome to the mpv forums! try exporting to 720p. Any improvement on the TiVo? Unfortunately, I've got no direct experience with the TiVo, and it sounds like if it plays back fine on mac/PC then it's a TiVi specific issue. Perhaps it doesn't handle 1080P so well... Hope that helps R
    Reply
  • john.vk5kg
    Posts: 2
    Joined: Dec 6th, 2010, 09:00
    Re: My iMovie 9 Video
    I have been battling this problem for some time and recently solved it (at least for myself) and also solved another problem along the way! The cause of the problem I was having relates to the fact that the video I wanted to upload to TiVo was 25 fps (ie PAL scanning rate) because that is the normal type of TV in Australia where I live. Now what is generally not known about the TiVo is that it can ONLY playback videos that are compressed using the same algorithms as is used for broadcast TV in the country in which it is intended - ie MP2 in US and Australia, and (presumably) MP4 in NZ etc. Since the TiVo has no native ability to re-compress video, that must be done by the computer which is being used to upload the video to the TiVo - indeed re-compressing is major part of the job to be done by the likes of Mac2Tivo etc. But what if (and I'm guessing here) the Software Developer of Mac2Tivo (and again I'm assuming) lives in USA; he or she would naturally test the software with locally available video (ie NTSC or at least 30 fps video) and may not have given much thought as to other types of video. In fact I believe that is just what happened, and as part of its encoding functionality, Mac2TiVo also converts all incoming video to 30 fps by periodically duplicating a frame which when played back on the TiVo results in jerky motion. To prove to myself that this was what was happening, using Mac2TiVo I uploaded some 25 fps video that had burnt-in time-code so I could step through the resulting video frame by frame on the TiVo and sure enough I saw duplicated frames (and also some missing frames curiously). And to make sure of what I was seeing I down-loaded the same video back to my computer and sure-enough it showed as having a frame rate of 30 fps (actually 29.97 fps - but that's another story!) So, let's pull all this together. I believe that there is a "bug" in the Mac2TiVo code (it's the same bug that's in TiVo Desktop that runs on Windows boxes to do the same task) that calculates the duration of the video in frames (at 25 fps) but then once it has duplicated frames etc to produce an upload at 30 fps, uses that total to signal when the upload is complete; this results in the upload quitting prematurely! So what can be done I hear you ask? Well, as far as Mac2TiVo and other software that was developed and tested in the USA without thorough testing, nothing! Unless you know the Software Developer and get him/her to check their code! However, there IS software freely available that will work, that won't quit partway, and will produce smooth motion video. It's called "pyTiVo" and it's available for free download at... http://code.google.com/p/pytivox/ It works for me! I now have smooth-motion video that looks as good on my LCD panel when played from my TiVo as it does when played on my computer screen. I hope this helps others.
    Reply
  • Rounik Admin
    Posts: 8713
    Joined: Dec 16th, 2006, 08:13
    Re: My iMovie 9 Video
    Thanks John for posting your solution. :)
    Reply
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