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  1. Member
    Join Date: Jul 2008
    Location: United Kingdom
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    i am trying to understand if DvD has a better video quality than blu ray or not???

    both dvd and bluray being considered @ max resolution

    from my understanding DvD's max resolution is 720 x 576 @ 25fps and max video bitrate of 9.8Mbs
    which results in (9.8*1024*1024) / (720*576*25) bits/pixel =0.9911.......

    and for blu ray.....MAx resolution 1920 x 1080 @ 24 fps and max video bitrate of 40Mbs
    which results in (40*1024*1024) / (1920*1080*24) bits/pixel = 0.8427.....

    can any one confirm if the numbers are correct?

    and does this mean that blu ray can have a larger picture but of lesser quality than the dvd.....???
    some one please help me understand.....thank you
    spread and enjoy love peace and harmony....CRB
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  2. Member
    Join Date: Jul 2008
    Location: United Kingdom
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    In a sense i am talking about the density at max resolution on dvd and bluray
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  3. Always Watching guns1inger's Avatar
    Join Date: Apr 2004
    Location: Miskatonic U
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    You can edit your post, rather than bumping it.

    Are you only comparing mpeg-2 encoding ? What your numbers aren't telling you is that while the per pixel numbers might be slightly smaller, this is over a far higher resolution with greater detail, and therefore overall, still provides a far superior picture.

    And this is without looking at H.264 encoding, which is far better than mpeg-2.

    Personally, I believe trying to quantify quality into fractional numbers is a waste of time. There are simply too many other variable at play for a single number to show anything. I have seen material encoded at high bitrates that is still very poor quality, and material encoded at a third lower that looks far better.
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  4. Member
    Join Date: Jul 2008
    Location: United Kingdom
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    so lower bits/pixel doesn't have to mean lower quality.........thank you...
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  5. Depends what you mean by quality. For me, resolution equals quality...mostly anyway

    BD packs more information into a larger "canvas". Watch the BD version of Patton. During his Close Up at the beginning of the film you can clearly see the Mesh used to glue on George C Scott fake eyebrows. While this example conveys the downside of higher resolutions, image what it does for the rest of the film.
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  6. Member
    Join Date: Jul 2008
    Location: United Kingdom
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    what i thought was that...less bits avilable per pixel equalls less information storing capacity per pixel.........so the increase in resolution is definately there...but the capacity to store information per pixel is less .....(as in my calculation above)....but as guns1inger pointed oout....the codec must play a huge role in information storing ...like may be H.264 has a higher rate of information storing capacity per bits than mpeg1/2.....
    spread and enjoy love peace and harmony....CRB
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  7. Banned
    Join Date: Jun 2007
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    The values of "bits per pixel" you have found refer to compressed info.
    The algorithms used by the various MPEG-4 "flavours" are more efficient
    than the ones used by MPEG-1 and MPEG-2.
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  8. Always Watching guns1inger's Avatar
    Join Date: Apr 2004
    Location: Miskatonic U
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    You also have to look at it overall. If you were comparing two files, encoded from the same source, with the same codec, at the same resolution, and one has a lower bit/pixel allowance, you may be able to make a case that one is of lower quality than the other. However if the the difference is small, there may be no visual difference between the two files.

    In the case you have presented, you are comparing two files of vastly different resolutions, but a much smaller difference at the bit/pixel level. Therefore overall, the larger image still holds substantially more information than the smaller one, even if at a granular level it appears to have less.
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  9. Member edDV's Avatar
    Join Date: Mar 2004
    Location: Northern California, USA
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    Originally Posted by crb
    what i thought was that...less bits avilable per pixel equalls less information storing capacity per pixel.........so the increase in resolution is definately there...but the capacity to store information per pixel is less .....(as in my calculation above)....but as guns1inger pointed oout....the codec must play a huge role in information storing ...like may be H.264 has a higher rate of information storing capacity per bits than mpeg1/2.....
    Your calculation comes down to bitrate per pixel. So I ask you (ignoring codecs) does 1280x720p @ 50fps mean higher quality in your model? What about 720x576p @ 24fps at max BluRay bitrate? Would that be best of all?

    There are many trade offs even for uncompressed video. Resolution, frame rate, 10 vs. 8 bit depth, 4:4:4 vs. 4:2:2 vs. 4:2:0 color space plus audio standards all contribute to quality and each is variable within a fixed bit rate. Different types of video (e.g. scenery vs. sports vs. talking heads) optimize differently. Codecs also have trade offs depending on source material and use in the transmission channel. MPeg2 has less loss through recode. H.264 recode should be avoided.

    The standards that have evolved for DVD, BluRay, ATSC/DVB,etc. are balances of all these variables. All variables can be maxed if you can handle the bit rate. 1920x1080p, 24fps, 10bit, 4:4:4 with 8 channel PCM audio takes approximately 4Gb/s bitrate. 1920x1080p, 24fps, 10bit, 4:2:2 fills 1.5Gb/s (1.485Gb/s SMPTE-292). To get that down to 25-35Mb/s BluRay, additional compromise is required as you can imagine.
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