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  1. Member
    Join Date
    Apr 2005
    Location
    Dover NH
    Search Comp PM
    Hi all,

    I'm using WinX DVD Ripper to create MP4 files from DVDs.

    In the 'Resolution' settings, the selection 'Keep Origin' appears to render a file that's 640 x 480.
    I determined this by playing the movie directly from the DVD, then ripping an MP4 with the 'Keep Origin' setting, then
    ripping an MP4 with the 640 x 480 setting.

    All files appear to be the same window size and quality on my screen.

    Now, when I select a higher resolution (960 x 640) the resulting MP4 is larger on the screen and the quality looks identical to
    the lower resolution. But I'm not sure if my eyes are playing tricks.

    I also noticed the file size hasn't changed either - in this case 300mb.

    All other video options are the same: Codec: Mpeg4, Frame Rate/Aspect Ratio: Keep Origin, Bit Rate: 1500.

    So my question is this - Does selecting a higher resolution change the final quality at all, or should it stay the same?

    My overall goal is to have these MP4's appear as large as possible on my computer without having to
    click on them to fill the screen.

    Thanks.
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  2. aBigMeanie aedipuss's Avatar
    Join Date
    Oct 2005
    Location
    666th portal
    Search Comp PM
    how big is your monitor? go for the same size. most are 1920x1080. filesize = bitrate x time. they all are going to be the same filesize if you keep the bitrate at 1500.
    --
    "a lot of people are better dead" - prisoner KSC2-303
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  3. It is usually recommanded to keep the native resolution, which is anamorphic 720x480 (or 720x576), displayed with an aspect ratio of 4:3 (which results in a default viewing size of 640x480 for 720x480 DVD) or 16:9 (which results in a default viewing size of 848x480 for 720x480 DVD), meaning that the picture is automatically elongated or shrinked, as if the pixels were rectangular instead of square (just like on the source DVD – standard DVD video is always anamorphic). I have never used that conversion software, but if it says that 640x480 is “origin” resolution for a DVD, it may not be very reliable. And if you're comfortable with 4:3 footage converted as 960x640, which corresponds to an aspect ratio of 3:2, maybe your eyes aren't very reliable either ! Unless it's automatically converted as anamorphic – what does MediaInfo say about those converted files ?

    As has been said above, if you keep the same average bitrate, the file size will end up approximately the same. But if you keep the same bitrate with a higher resolution, the quality will be inferior (less bits per pixel). You may not notice it easily if the difference in resolution is not too big, and if you don't know what to look for, but it's a fact. If you want to upscale (increase the resolution) you have to increase the bitrate. But upscaling DVD resolution to 1920x1080 seems like a waste of storage space, considering that it's going to require at least 4x the bitrate of a native resolution conversion to get a decent result, and it won't improve the quality of the source ; meaning, a video converted to anamorphic 720x480 MP4 with an average bitrate of 1500kbps will look as good when upscaled to full screen by the software or hardware player as the same video converted to 1920x1080 MP4 with an average bitrate of 6000kbps.

    Using a one-pass CRF based encoding (Constant Rate Factor) would be more efficient in any case : you select a certain level of quality, and the encoder allocates bitrate accordingly ; the drawback is that you don't know the size of the transcoded file beforehand, and if you convert several source videos with the same duration (episodes of the same show for instance), the resulting MP4 files will have a varying size, but unless there are specific storage restrictions this shouldn't be a problem, and it allows for a better use of bitrate (for instance, in the same season of the same TV series, there can be an episode which is mostly quiet, with a lot of well-lit talk scenes, and the next one with full-blown action in a dark and rainy setting – if those two episodes are converted with the same average bitrate, and end up being the same size, the quality of the latter will suffer in comparison with the former, whereas if converted with the same CRF setting, the size of the latter may be significantly larger but the quality will be consistent).
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