HB ATV3 Preset Gives me 4GB files and 17GB Files?!?!?! HUH?

Discussion in 'Apple TV and Home Theater' started by mcpreaches, Sep 11, 2012.

  1. mcpreaches macrumors newbie

    Sep 8, 2012
    Ok so I was wondering if somebody can explain this to me. I was backing up my copy of Breaking Bad (BR) season 1 and One episode was 2.5 gigs then another was like 6.5 and When I backed up the Godfather it came out to 17GB.
    All I am doing is picking the ATV3 Preset and that is all, no changes. Can anybody explain why there is such varying sizes?
  2. blevins321 macrumors 68030

    Dec 24, 2010
    Winnipeg, MB
    I'm having the same quandary. Hunger Games was approx 15 I think. Not as severe a problem when I choose the high profile instead. Basically I just want a 1080p version of the 720p ATV2 preset.
  3. benh911f macrumors 6502

    Mar 11, 2009
    Not sure about the big discrepancy in size between Breaking Bad episodes, but of course The Godfather is going to be about 3x the size of BB. Those episodes are, what, 45 minutes? Whereas The Godfather is 3 hours.
  4. mcpreaches thread starter macrumors newbie

    Sep 8, 2012
    I know that the Godfather is going to be bigger but for example I have one 2 hour movie that is like 5GB and then Scarface that is shorter running like 15GB. I just don't understand how the same lengnth movie can be almost twice the size... ie 5gb to 15gb.
  5. Menneisyys2 macrumors 603

    Jun 7, 2011
    It might contain a lot of action scenes? Therefore the bigger size.

    BTW, 3 hours for a 1080p video using (comparatively) high quality is pretty much the norm.
  6. Cinephi1e macrumors regular

    Jul 19, 2012
    Northwest Ohio
    That sounds about right for The Godfather at 1080p. The original video is somewhat grainy and that accounts for the large size (and the length). If you are ripping at 1080p you have to expect such sizes for some movies.
  7. martinm0 macrumors 6502a

    Feb 27, 2010
    Has anyone noticed movies being larger than expected since the last update of HB? I have no real data to support this (and probably have some to refute it), but anyone else feeling the same way?

    I set up my own preset a while ago starting with the ATV2, bumped it up to 1080p, set a strict aspect ratio, and added a 3rd soundtrack (2ch, DD5.1 and DTS passthru). I leave everything else as is (CQ is 20). What I'm noticing is that some movies are coming in well over 10GBs. Sure, some are longer than others, but my gut is telling me something has changed...

    My evidence: Well, I don't really have any. Unfortunately, I did reconvert a movie that I know I encoded before the update, and sure enough it came out at the same size. I know, I know. That pretty much answers my question. But I have Moneyball (135 mins) that's over 15GB, while Man on a Ledge (105 mins) is just over 6GB. Not really apples to apples (I'm sure Moneyball has more grain that adds to the size, plus its 30 mins longer), but its well over twice the size.

    Anyway, I'm sure I'm crazy, but interested if anyone else has the same gut feeling...
  8. mic j macrumors 68030

    Mar 15, 2012
    No, I don't think file size has changed. The mind tries to find patterns in "noise". The fact that you got the same size on the same movie, transcoded twice, is your proof.
  9. HobeSoundDarryl, Sep 12, 2012
    Last edited: Sep 12, 2012

    HobeSoundDarryl macrumors 604


    Feb 8, 2004
    Hobe Sound, FL (20 miles north of Palm Beach)
    Guys, several of you are over-simplifying this. A movie at- say- 100 minutes vs. another movie at 100 minutes is not going to end up the same file size. Classic example...

    Imagine you own a 1080p camcorder- even the one in iPhone 4s-. Now, lock it in place and aim it at a single color backdrop (say, a white poster). Edge to edge, top to bottom it's shooting the exact same thing: one big 1920 x 1080 image of uniform white for 100 minutes.

    Then, go get in the passenger seat of your car and have someone drive you down the highway for 100 minutes. Hold the iPhone in your hand this time (so that it is not as stable) and aim it out the window so that it is shooting an ever-changing scene going by as you ride along. In this clip, just about every pixel is changing for every frame that is shot.

    Both the first and second video is shot for exactly 100 minutes with the same camera, at the same resolution, etc. Will the file sizes likely be identical or will one be bigger than the other? A little bigger or a lot bigger?

    Metaphorically become the camera. You've got 100 minutes * 60 seconds in a minute times 30fps, or 180,000 sheets of blank paper. Your job is to document what your lens (your eyes) see in front of you as good as possible by drawing it. The task is to be able to play back what you see for someone else so that they get a pretty good sense of what you saw when you "recorded" your film. You'll need super speed for this so put on your Flash costume.

    If all your eyes can see is the white backdrop, page 1 is left blank. No changes for page 2. No changes for page 3. No changes for page 4. Etc. By the end of your "shoot", you don't even need 179,999 of those sheets. You can just have your audience watch frame 1 repeating 180,000 times and they will see exactly what you saw when you recorded your film. That's some amazing compression.

    Now, back on that highway again. Page 1 has a wide range of varied detail so there's a lot to draw on that page. Page 2 will involve redrawing pretty much everything again because the car moved a tiny bit down the road, maybe it is rising or falling just a bit on the uneven surface or maybe your head is bobbing just a bit. Page 3 requires redrawing every single "pixel" anew too. And so on. You end up with 180,000 unique drawings- each fairly significantly differing from the previous ones.

    Unlike with the plain background "video", you can't toss out any frames for compressing this "video". Instead, you'll have to retain upwards of all 180K frames to flip through for showing your audience what you saw.

    Video 1 was thus compressed down to a single page and recreated the "film" you shot exactly as you saw it. Video 2 couldn't be compressed down anything like that because replication of the content of what you saw involved an ever-changing image as your car rolled down the highway. Both play for 100 minutes and both are gridded on your drawing pad with 1920 x 1080 unique "pixels". However, the pad (file) sizes would be massively different.

    Bring it back to movies. Some movies have more imagery to capture. Others have less. Line up 100, 100-minute movies and you'll probably get a different file size for every single one... even with the same HB profile and same resolution. Some will vary significantly based upon the level of detail that must be documented in the file.

    The variances simply mean that it is what it took to capture the detail of the whole film at whatever quality level you were seeking. If you compress your plain white background film, it will probably end up amazingly small (file size). Why? Because it takes so little visual documentation to be able to play back a single color for 100 minutes. Of course, a detail-less movie is going to be a very boring movie to watch. Thus, we like detail-rich movies. Some of them are going to require visual documenting at greater levels than others. It's what it takes to play it back as we are supposed to see it.

    Short answer: if you like the quality of film, buy some bigger hard drives to hold those bigger files. If you are more stuck on file sizes, crank up the compression (and thus squeeze out the visual detail) to achieve the small files you desire. The latter won't look as rich as the former but it will yield smaller files.
  10. dynaflash macrumors 68020

    Mar 27, 2003
    Well said. As well it also is the reason HB's encoding time will vary. Complex details take longer for HB to analyze. A black screen is quite fast. This is one reason HB will typically start out encoding at a much higher fps at the very beginning and end. This is typically where the intro for the movie ( studio splash screen etc) and end credits are. Typically dark scenes with are very un complicated.
  11. imMango macrumors member

    Jun 10, 2011
    Grains a bitch when encoding. Both Breaking Bad and The Godfather are pretty bad offenders.

    I'd recommend, if you are wanting relatively similar sizes for TV episodes, is to encode with avg bitrate. I also have been doing avg bitrate encoding for movies as of late as I usually have a good idea of the file size I'm trying to hit for any particular movie (depending on the type of movie, aspect ratio and grainyness)

    Otherwise, you'll need to tinker with RF settings (increase it) and/or noise reduction to lower the file sizes.

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