handbrake conversion and framerate change

Discussion in 'Apple TV and Home Theater' started by chenks, Jan 31, 2012.

  1. chenks macrumors 6502a

    chenks

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    #1
    converting a few files using handbrake (tried current stable and current nightly).

    have noticed that when using the appletv2 preset, it seems to always want to change the framerate to 29.97 NTSC.

    the framerate of the content is 25fps, and the appletv can play that framerate, so why does the preset insist on wanting to change it to 29.97?
     
  2. peterjcat macrumors 6502

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    #2
    It's just talking about the maximum framerate; anything higher than 29.97 will be converted down but 25fps will stay at 25fps.
     
  3. chenks thread starter macrumors 6502a

    chenks

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    #3
    are you sure about that?

    any "howto" document i've seen that uses handbrake always seems to suggest changing that setting to "same as source".
     
  4. MonkeySee.... macrumors 68040

    MonkeySee....

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    #4
    Sorry to hijack your thread but i've had an issue with the Apple TV 2 preset with regards to .avi being converted. MKV's seem to be fine but converting an avi seems to destroy the quality?

    Any ideas?
     
  5. chenks thread starter macrumors 6502a

    chenks

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    #5
    probably best to start your own thread and to supply specific info about your files.

    i'd rather keep this thread about the framerate setting.
     
  6. fred.bloggs, Jan 31, 2012
    Last edited: Jan 31, 2012

    fred.bloggs macrumors member

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    #6
  7. chenks thread starter macrumors 6502a

    chenks

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    #7
    so if i changed the setting to "same as source", what difference, if any, would there be if it was left at 29.97 ?

    why do most of the howto resources (usually regarding bluray conversion) suggest changing it to "same as source" ?
     
  8. bucksaddle macrumors 6502

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    #8
    None really, but see roidy's response in this thread as to why the preset now uses peak framerate.

    http://forums.macrumors.com/showthread.php?t=1080374

    Note that the checkbox roidy talks about has changed and doesn't exist anymore in the latest nightlies, but the radio button "Variable Framerate" changes depending if you select "same as source" or any constant framerate.
     
  9. rayward macrumors 68000

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    #9
    I learn something new every day! I have been changing the Apple TV2 and iPhone 4 presets to "Same as source" for BD movies because I didn't want HB to change the original framerate. Now I know I can ignore that step. Thanks.
     
  10. chenks thread starter macrumors 6502a

    chenks

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    #10
    as a rule you never want to change the framerate.

    with the original appletv, the preference was to drop the resolution so that the appletv could play the content at the original framerate. the appletv2 doesn't have that specific issue though.

    this is why i asked the original question.
     
  11. dynaflash macrumors 68020

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    #11
    The original atv (atv 1) cannot play back 29.976 fps video at 720p ... which is why that preset scales back to 540p. you are correct in that the atv 2 can playback 720p30fps so no downscaling from 720p is required.
     
  12. rayward macrumors 68000

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    #12
    I have only ATV1s, and they play encodes from Blu Ray movies just fine, but they are at 23.976fps. For TV Shows at 29.976fps, I change the frame rate to 25fps to maintain 720p playability on my ATVs.

    I haven't tried letting it default to 540p to see which is better. The 720p/25fps encodes look great.
     
  13. dynaflash macrumors 68020

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    #13
    Right for the atv 1 there are two choices with 29.976 fps content (ntsc video). Scale down to 540p and keep the source framerate or drop the framerate to 25 fps and scale to 720p. As to which looks better ? it depends if you notice the almost 5 dropped frames per second from dropping the framerate.

    Its worth noting that the atvs upscale quite well really and even at 540p your still well above standard dvd which is 480p. It should look smoother on 29.976 fps content. But as always only your eyes can tell you which you like best, so go with it.
     
  14. chenks thread starter macrumors 6502a

    chenks

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    #14
    a follow up question to this.
    i'm using one of the nightly builds (although i believe it is the same on the current release version).

    using the appletv2 preset, i notice the anamorphic resolution is lower than desired resolution that the appletv2 can play.

    original resolution of the file is 1920x1040, output resolution is 1280x688 which is what should be fine for the appletv. anamorphic resolution is 1275x688 Loose.

    should i be tweeking the anamorphic settings in the preset?

    [​IMG]
     
  15. rayward macrumors 68000

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    #15

    Yes. You should change the anamorphic setting from "Loose" to "Custom", and then bump the vertical number from 688 (or whatever it happens to be on any other file) to 720. You will get an ATV-friendly 720 lines vertically, but greater resolution horizontally (depending on how wide the source file is) that will play without issue on your ATV.
     
  16. chenks thread starter macrumors 6502a

    chenks

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    #16
    why would i want to change the vertical though?
    1280x688 is the correct resolution it should be.

    ie the original is 1920x1040 (1.85:1 aspect ratio).

    why does the built-in atv2 preset have this anamorphic setting as default?
     
  17. chenks thread starter macrumors 6502a

    chenks

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    #17
    just tested your suggestion and it resulted in a 1338×720 file.
    that's not what it should be, it should be 1280x688.
     
  18. dynaflash macrumors 68020

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    #18
    Anamorphic in hb was originally designed for dvd sources ( also blu ray). your source is quite obviously .... neither ;) since its an mkv torrent.

    So, in this case I would just turn off anamorphic. That way it will just grok the output size.

    Note also that anamorphic and output will by default observe a modulus of 16 (rounds to the nearest 16 pixels) so might not always match the source. You can change this in the Picture Settings.
     
  19. chenks thread starter macrumors 6502a

    chenks

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    #19
    cool that seems to produce the correct output.

    now just to tweak the quality settings.
    default seems to be constant quality 20. this could probably be upped a little. any suggestions?

    or is it better to use average bitrate?
     
  20. dynaflash macrumors 68020

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    #20
    constant quality beats abr every time. just adjust the rf scale to what you want. too much to talk about here. start with the preset value of 20, it should be fine for most every source.
     
  21. chenks thread starter macrumors 6502a

    chenks

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    #21
    yeah, only reason i asked is that the file size seemed a little small with it set to 20.

    i had previously been downloading file already converted for appletv2, and the file sizes and average bitrate were higher than the file i created.

    how big are the increments in the constant quality scale? is 20 to 21 a big jump, or is 20 to 30 a small jump?
     
  22. dynaflash macrumors 68020

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    #22
    Its a logarithmic scale. so 20 - 19 is a decent sized jump bitrate wise ... 19 - 18 is bigger yet proportionately.

    bitrate is not always an indicator of quality.

    https://trac.handbrake.fr/wiki/ConstantQuality
     
  23. rayward macrumors 68000

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    #23
    Which do you think has greater resolution?

    1338 x 720 = 963,360
    or
    1280 x 688 = 880,640


    The settings tweak lets you create a file of greater resolution that will play without issue on an ATV. I do this all the time, and I have 1st gen. ATVs - never a problem.
     
  24. chenks thread starter macrumors 6502a

    chenks

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    #24
    1280x688 is the "correct" resolution. i'll stick with that.
     
  25. peterjcat macrumors 6502

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    #25
    Neither resolution is inherently more "correct" than the other, but if you only play back via ATV2 there's no advantage in the 1338 x 720 resolution as the ATV2 will scale it down to 1280 x 688 to fit within the 720p frame anyway.

    The constant-height Custom Anamorphic setting is used to maximise vertical resolution for playback on devices that support greater than 720p output (e.g. Mac/PC, ATV1, ATV3?, any other media player) while maintaining broad ATV compatibility.

    Rayward's math isn't quite right, though, as the Custom Anamorphic setting doesn't actually add any information to the horizontal axis, it's still 1280 x 720 pixels but the pixels are rectangular rather than square.
     

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