.OGM, .avi files to ipod video

Discussion in 'iPod' started by macOSX-tastic, Nov 8, 2005.

  1. macOSX-tastic macrumors 6502a


    Jan 9, 2005
    At the Airport. UK
    hi guys, havent posted in a while, but see how you can help me out here:

    i have several movies in obscure file formats that were sent to me from a PC (my friend's). basically, i can only play these files in VLC player, which is fine for the computer, but i wouldnt mind putting them on my new video as i like to keep all my movies syncronised, and these just wont.

    the file formats are .OGM, and .avi (even though this should play in quicktime, apparently it's missing an important codec for this type of .avi and im not sure which one it is. im sure that if i could find it, i could do a quicktime to ipod like all my other movies.)

    sorry about the incoherency of my post, if any, as it is 1:45 AM here and i cant sleep.....

    thanks for any input guys, appreciate it.
  2. kugino macrumors 65816


    Jul 10, 2003
    there's an app called MovieToGo, which converts those files (at least .avi) to mp4 for use on your ipod. it's VERY slow, though.
  3. macOSX-tastic thread starter macrumors 6502a


    Jan 9, 2005
    At the Airport. UK
    MOvie to go......how long are we talking here (on average) for a 5 minute 640X480 movie, to use an example?

    thanks very much!
  4. bepster macrumors member

    Oct 21, 2005
    ...I have another question about encoding .avi-movies (for example 700mb vs 1.3gb).

    well, If I covert a movie the same way with the same settings into mpeg4 (for my ipod and than TV) from a 700mb or from 1.3gb, which one will turn out better??

    in my theory, they will look the same and have the same size, can naybody confirm?
    here's my logic (I hope you can understand it, it's a little wierd ;) ):

    Image you have a cake, sliced into 10 pieces (1.3gb avi) and a cake, half the size, sliced into 5 pieces so that all the pieces (700mb) have the same size.

    now you need 4 pieces (mpeg4 for the ipod)...
    so if you take the needed 4 pieces from the big cake or from the small cake, doesn't matter, right?

    same question goes for dvd (4.2gb)...

    would be cool if anybody would have a point on this...
  5. Battousai macrumors member

    Nov 4, 2005
    I think that the files will look the same. They're both being reduced to the same resolution and bitrate.

    Here's an analogy that I think is slightly more clear:

    You have two pieces of rope, a 7m piece, and a 10m piece. If you cut a 3m piece off of both of them, then the 3m pieces will be exactly the same, despite coming from ropes with different original lengths.

    However, I'm not a video expert, and there is a very good possibility that I'm wrong. However, I do know that even if there is a difference, by the time you take a 700mb and a 1.3gb file and reduce them to 320x240, or even 640x360, the the difference will be so small that you won't even notice it.
  6. bepster macrumors member

    Oct 21, 2005
    ...but am I really reducing a 700mb avi-file?
    when encoded to mpeg4 with a 1200-bitrate, it turns out to be 1.1gb, a lot bigger than the .avi!

    is that because mpeg4 takes much more space or am I really improving the quality of the original file (avi) which had a lower bitrate, it was only 700mb big?

    I was wondering if that is really possible, to improve the quality of the 700mb-original only by encoding!
    that would mean that the rope- and cake-analogy wouldn't be true...
    'cause you would have 5m of rope and after encoding you suddently end up with 8m!

    the questions:
    1. does avi take less space than mpeg4 and is that why my movies get bigger after encoded with the same bitrate and resolution?
    2. can I improve a low-quality rip (700mb for a movie) with encoding to avi just through pitching up the bitrate and resolution or can a movie never be better than it's original quality??

    what do the experts say?? I am lost in this idea :eek:
  7. Makosuke macrumors 603

    Aug 15, 2001
    The Cool Part of CA, USA
    From the numbers you gave (it was a ~2 hour file, right?) you basically reencoded a 745kb/s AVI file into a 1200kb/s MP4. This is a guaranteed waste of space for zero quality gain (a slight loss, in fact, as reencoding will always reduce the quality somewhat).
    1. If you're talking about AVI files encoded with either DivX or XviD (most now are, but there are dozens of other codecs possible), and an MP4 encoded with h.264, then the MP4 will be a smaller file at the same quality level, or better quality (sharper or larger frame) at the same bitrate/filesize. If you're using the older video codec available in MP4, then they're about the same.

    2. Absolutely not. You can never end up with an image better than what you started with. If you were so inclined, you could make the reencoded file as big as you wanted--you could, for example, go from a 100MB crummy-quality AVI to a 4GB equally crummy-quality DVD--but that's a waste.

    What you want to do since you're starting with AVIs and aiming for something that knows how to play h.264 is to reencode at about 2/3 the bitrate of the original file; you will, as always, lose some quality doing this, but it won't be much. Alternately, if the original files are at 640X480, if you're reencoding for an iPod at 320X240 (or something a bit larger) you can probably go down to half the original and not have a huge additional loss in quality.

    One more thing: If the AVIs you're having trouble with give an "unrecognized file type" error when you try to open them in QuickTime Player, I'd bet money that they're actually mislabeled OGM files--those seem to be oddly common these days, I assume because idiot Windows users change the .avi extension to .ogm so it'll automatically open in their default player or something.
  8. bepster macrumors member

    Oct 21, 2005
    wow, thank you, you are really helping me out here!!

    so increasing the bitrate during encoding an .avi-file (dvix) has no point then! The best is to stick to the original bitrate because the quality can't be improved, right?

    The thing I care the most about, is TV-playback!
    everybody keeps telling me that for tv, mpeg4 is the way to!

    is this not true than and just a waste of space??
  9. Makosuke macrumors 603

    Aug 15, 2001
    The Cool Part of CA, USA
    Basically, yes. Since any time you reencode a video from one format into another, you're loosing some quality, technically by going with a higher bitrate you would preserve more of the quality you started with, but it's going to be a lot of extra space for a very small quality gain. Since you're going lower quality from the get-go, you might as well save a little extra, since it won't make much difference in quality anyway.

    Um, no? You said you're trying to play your videos on an iPod, and if that's the case you don't even have much choice of formats--either MP4 or Mov, and the only two video options are MP4 video and h.264, either of which works with either container format.

    Perhaps what's confusing you is that when people are telling you to export to "mp4", they mean an MP4 file, not "MPEG-4 Video Compression"; it's a little confusing on account of the names. .mp4 *files* are in the same category as .mov, .avi, and .ogm--they're all container formats. Each can have one of several different audio and video codecs contained within them. In the case of .mov and .mp4 files (.mp4 is closely based on .mov), you can even include other data formats, like text tracks or still images.

    MPEG-4 video, however, is a different beast--that's a video codec that was the original default for .mp4 files, although it's also used in .movs and I've even seen it in .avi files. The MPEG-4 codec is roughly equivalent of DivX and XviD, the AVI standards, in compression quality.

    h.264 is a newer video codec that can also be used in .mp4 files, and is the big deal with Quicktime 7. It provides significantly better compression than MPEG-4 or any of the older formats used in AVIs, so it's a very good choice for putting video on your iPod.

    When people are telling you to go mp4, they mean an .mp4 file with h.264 video. You could just as well use a .mov, but .mp4 (or rather .m4v) is the default for the iPod, so you might as well stick with it.

    So one more time: Export an .mp4 file using h.264 video at somewhat lower bitrate than the AVI you're starting with and a frame no larger than 320X240 (actually, technically, it'll play anything up to 480X480, or any numbers that multiplly out to 230,400 or less), and you're good to go.

    Here's an Ars Technica article on how to do it using the shareware FFMPEG:

  10. bepster macrumors member

    Oct 21, 2005
    wow, so much information!!

    really cool, that you are providing all this, thanks man...

    but the questions never end... ;)

    on the apple-website, they say taht the ipod can play h.264 up to 320x240 and MPEG-4 up to 480x480...

    you say, I can encode a file up to 230,400 in h.264 and my pod will play it?

    so the apple-website is wrong?
  11. Makosuke macrumors 603

    Aug 15, 2001
    The Cool Part of CA, USA
    I don't have one, so I don't know. Assuming you do, why don't you just try it? It only takes a few minutes to compress a few-second clip, so why not just make a few with different settings and experiment to find out.

    The things I'd read implied that 480X480 applied to h.264 video as well, but perhaps I read it wrong. In any case, though, I'm pretty sure that the restriction is number of pixels, not the dimensions.

    Also, remember that (if memory serves) when compressing video you want to keep each dimension as a multiple of 16. (At least, I THINK you do--most older codecs were more efficient that way, and I'm fairly certain basic MPEG4 is--is that true with h.264?)

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