Q. Handbrake and Inconsistent File Size

Discussion in 'Apple TV and Home Theater' started by HelixOmnimedia, Mar 23, 2014.

  1. HelixOmnimedia macrumors 6502a


    Jul 26, 2006
    Traveling The World

    So I've used Handbrake to make most of BluRays digital, however there are two movies I can't get my head around about file size.

    Back To The Future - Part 1 and Mary Poppins - when using the exact same Pre-Set I've used for others (including BTTF Part 2 & 3) come out HUGE. I'm talking 22GB per movie. When the others are coming in at 6GB.

    Any idea what could be causing it? I just find it really really strange. I would like these two BluRays in digital format but not at the current file size.
  2. cardsdoc macrumors 6502

    Jun 9, 2007
    Shaker Hts, OH
    That's pretty normal although not sure I have any movies quite that large. It's due to variation in complexity of the source. The largest factor for x264 seems to be film grain. Mine seem to range from ~4gb to ~15gb.
  3. brand macrumors 601


    Oct 3, 2006
    Without providing the settings that you are using it is very hard to help you.

    BluRay are already digital as well as DVDs and CDs.
  4. Billit macrumors member

    Jan 6, 2013
    As it so happens, I just did the Blu-ray BTTF 25th anniversary trilogy this weekend.

    Using the Windows version of HB version, 64bit, with the default High Profile preset, down-mixed DTS to a AAC and a AC3 audio track, no subtitles, Part 1 came out to roughly ~10.5GB, Part 2 at ~6GB and Part 3 came in at ~6.5GB.

    Even though I cannot currently use DTS with the ATV3 that I have, I also did a set that included the DTS (pass through) track. That came out to Part 1 at ~14GB, Part 2 ~9GB and Part 3 at ~10GB. Adding the DTS track seems to add ~3-3.5GB to the file size.

    I have no idea why you would be getting ~22GB for Part 1 when I got ~14GB and that includes the DTS track.
  5. StinDaWg, Mar 23, 2014
    Last edited: Mar 23, 2014

    StinDaWg macrumors 6502

    Apr 5, 2012
    Seems about right. 1080p encodes from reputable p2p groups are around 18-23GB. The first film is very grainy compared to the last two.

    Fun fact: the DCP source that was leaked online and never commercially released blows away the Blu-ray in terms of quality.

    It's a long thread, but there are some comparisons toward the end.

    Edit: here you go

  6. westrock2000 macrumors 6502a

    Oct 18, 2013
    That's one of the downsides to using Constant Quality as opposed to Avg Bitrate on the Video Tab. Avg Bitrate is very consistant when it comes to file sizes, but the downside is you have to either have a blanket number that is more then normally used so as to cover unexpected high movement scenes, or somehow know ahead of time what you need.

    I ended up using Avg Bitrate and just came to accept that movies would be a certain size. I found Constant Quality to be wildly different when it came to animations. I had 1080P movies that varied from 3 or 4GB up to 20+. And smaller files, did suffer in picture quality.
  7. dynaflash macrumors 68020

    Mar 27, 2003
    Grain is the biggest cause of large file sizes when using Constant Quality. That said it will give you the same visual quality across a range of sources, bit rate be damned. Back to the Future 1 is from 1985 iirc and is quite grainy so the encoder tries to duplicate all of that grain detail to remain true to the source. A worse source is Saving Private Ryan which is newer but has a lot of artificial film grain.

    Average Bitrate sticks to a user specified bitrate but visual quality be damned. The big problem with using ABR is that there is no way you can have a set bitrate for every source and maintain an even visual quality throughout your library. you simply are not as smart as the encoder is. That said if you are okay with varying visual quality throughout your library you will end up with predictable file sizes (bitrate x length) so if you don't mind the varying quality of your encodes it may be the way for you to go.

    Also, its worth noting that using a random average bitrate may cause you to use too much bitrate in sources that do not require it. For instance clean animation etc where there is virtually no grain. Still scenes etc where there is little detailed movement. Constant Quality will drop the bitrate significantly on those scenes as there is no reason to use a higher bitrate to maintain quality. Conversely if you have chosen an average bitrate it will be maintained even though not needed causing larger than needed file sizes.

    Lastly if you have a source like BTTF or SPR that bloats file sizes abnormally due to heavy grain via Constant Quality, there is also the option of using the Denoise filter which filters out some of the grain before it hits the encoder, in which case the encoder doesn't try to duplicate the originals graininess and thereby uses less bit rate. Makes a pretty big difference on those sources.

    Just my .02

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