BluRay Creations are Small

Discussion in 'Issues and Bugs' started by Irondad, Dec 24, 2016.

  1. Irondad

    Irondad New Member

    You had someone talk about Ben-Hur bluray creation being too small. I have had the same problem with, Ben-Hur 10.8GB, Suicide Squad 13GB, as well as Pete's Dragon 7.45GB. Discs play fine. I have the latest installed 8081, 1110. I'm using two Nvidia 970's in SLI setup for GPU acceleration. Any suggestions?

    Amd 4350
    Win 7, 64 Bit Pro
    32GB Memory
     
  2. Ch3vr0n

    Ch3vr0n Translator NL & Mod

    Yes, CloneBD logfile please.

    Sent from my Nexus 6P with Tapatalk.
     
  3. DrinkLyeAndDie

    DrinkLyeAndDie Retired Moderator

    A developer will be able to better explain the reasoning for smaller output. Too technical for me. :) The usage of the hardware acceleration - CUDA, in my experience - and how the encoder is designed is what i suspect is behind what you are noticing. This does not mean the quality is poor. There are simply differences between software and hardware accelerated encoding. :)

    PS: While I suspect there is no bug here and what I said is why you are seeing the smaller than expected output I would still attach logfiles as Ch3vr0n requested.
     
  4. Ch3vr0n

    Ch3vr0n Translator NL & Mod

    I do think that reto or Pete said there's a bug in clbd that for Nvidia it doesn't account for bitrate under certain conditions. And there's a similar one for AMD too I think.

    Sent from my Nexus 6P with Tapatalk.
     
  5. skippy

    skippy Well-Known Member

    Hello,

    I confirm for Ben Hur because was my post, since i update the amd drivers but still the same. We have to wait a fix, be confident.
     
  6. Irondad

    Irondad New Member

    Here is the log file you requested. This time I just created an iso file. It is even smaller than the disc version.

    Sent As requested.
     

    Attached Files:

  7. Pete

    Pete Forum Admin Staff Member

    That was actually about AMD only.
    nVidia mostly does a good job there, but sometimes results are smaller for nVidia, too. No real cause found, yet.
    Most likely cause, because it depends only on the raw decoded picture input: the input is not detailed enough to merit larger bitrates.
     
  8. Sabertooth

    Sabertooth Well-Known Member

    I have this happen all the time with the nVidia encoder. Adjusting the size manually won't help typically and I fall back to BD Rebuilder to get the size I want. Here's the latest one:

    Passengers (2016) Partial Copy to Folder, Target size (Custom BD-R): 24.5 GB (2464 mbps), Resultant size: 18.2 GB, log attached. The original materials size is less than 30 GB due to removing the French HD Audio and Spanish language tracks and subtitles.
     

    Attached Files:

  9. DrinkLyeAndDie

    DrinkLyeAndDie Retired Moderator

    I've experienced this myself and it has to do with the NVIDIA hardware acceleration. An example was Bad Moms which resulted in output that was a mere 9.94 GB when using software encoding resulted in output that was 22.4 GB. Visually I really didn't see a difference which baffled me but it just felt like a waste of a BD-25 blank if a person was making a backup. This is obviously completely dependent on the source material as to the final output size rather than it being something that is always happening. I haven't seen it at all with software encoding but that, obviously, increases the time needed to create output. AFAIK with NVIDIA hardware acceleration a desired average bitrate is used which can result in undersized content. VBR is used rather than CBR. If CBR was used the output size would be more accurate to what you wanted but would be really be better? That doesn't mean your 18.2 GB output is poor quality, however.

    Check out this post by Reto which gives some explanation: https://forum.redfox.bz/threads/ben-hur-bd-movie-25gb-10-gb-why.71456/#post-456240 . That's mostly an AMD thread but I temporarily sidetracked it with a question related to NVIDIA undersized output.
     
    Last edited: Mar 19, 2017
    nebostrangla likes this.
  10. Pete

    Pete Forum Admin Staff Member

    ...well you could just as well simply turn off hw acceleration instead of using another software.

    This is exactly the point. We made a couple of tests in that direction.
    And they seem to confirm what Reto said.

    Elby could add filler data (and I suspect, that's what sw mode does automatically), just so people are happy with the larger "size", even though the quality is the same. Makes no sense, but what does these days...?
    As mentioned, CBR would do the trick, but unfortunately is no option, at least for Blu-ray output, because CBR is not covered by the BD specs.
     
    nebostrangla likes this.
  11. Adbear

    Adbear Well-Known Member

    Are you sure that CBR isn't allowed? I have many Blu-ray authoring packages and they all allow for h264 CBR
     
  12. Pete

    Pete Forum Admin Staff Member

    To be honest, I wouldn't place a bet - but regarding all constraints laid out in the specs regarding elementary stream buffer requirements (min/max/overflow/vbv buffer size), they do all point towards a classic VBR scenario and they make no sense with CBR.
    But I admit, there is no explicit mention of "CBR" or "VBR".
    There is one thing that did clearly speak against the use of CBR: experiments with CBR revealed that some standalone players (I remember Panasonic, I think a Samsung as well) refused to play those results at all (PowerDVD and all those non-licensed media players had no problems, though, but that's no surprise).
    So that's one reason why CBR is not being pursued as a valid alternative (the other being that it is generally not a very good choice when it comes to video from a disc - a lot of the time it's a waste of space and the rest of the time it's a waste of quality, it's lose-lose).
    The only reason it was even considered, was to make those happy, who are complaining about small file sizes (even though, rationally speaking, there is no benefit).
     
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  13. Ch3vr0n

    Ch3vr0n Translator NL & Mod

    Well before CloneBD I used bd-rebuilder. Many of its outputs were made with automatic quality that used CBR. Both my Panasonic bd85&110, as well as my mom's bd50 played them just fine.

    Sent from my Nexus 6P with Tapatalk.
     
  14. Pete

    Pete Forum Admin Staff Member

    Well, then maybe the trouble was coincidence and had a different reason.
     
  15. Pete

    Pete Forum Admin Staff Member

    Then again...
    can you point me to a source that says that the "automatic quality" setting in BDRB means "CBR"?
    I'm having a hard time imagining, that a video conversion tool would deliberately do CBR encodings by default.
    And I don't think BDRB does CBR.

    As far as I can tell - BDRB allows either CRF or ABR. CRF is "constant rate", which is the exact opposite of CBR and ABR means "average bitrate", which is exactly what CloneBD does - aims at a preselected average bitrate, which is typically not constant.
    Anyway, both is not CBR.
    And the "automatic" setting, as I understand it, merely preselects one of both (probably) and the basic quality preference.
     
  16. Adbear

    Adbear Well-Known Member

    I've encoded my own Blu-rays for work using Edius, and Edius will only allow you to encode into strict Blu-ray formats and it allows CBR.

    Scenarist even has it's own encoder to make complaint files for Blu-ray authoring and it supports CBR
     
    Last edited: Mar 20, 2017
  17. Pete

    Pete Forum Admin Staff Member

    Doesn't matter - CBR is no solution.
     
  18. Ch3vr0n

    Ch3vr0n Translator NL & Mod

    I didn't say automatic quality meant CBR. I simply stated that for some encodes it did. Automatic for bdrb means that it goes through some algorithm and does some analyzing to determine the best result. This can be 1 pass, 2 pass, vbr ...

    And for the record, I have no issues with some outputs only being 18GB or something. To me it's the visual quality that matters. Not the final GB's

    Sent from my Nexus 6P with Tapatalk.
     
  19. Sabertooth

    Sabertooth Well-Known Member

    I've reported for a long time (for example see here) that the software encoder doesn't play nice with my i7-6950. besides using less than 20 cores I often get less than 65% CPU utilization according to CBD (even as low as 30%). This causes the encodes to take a loooong time. No thanks.

    Okay, so while I understand the argument that the encoder can't squeeze water from a stone, if the source is padded or for whatever reason that it's not able to hit the size target, that's all irrelevant to me. The software hides almost all that technical stuff from me so my only concern is that the software does not hit the target that it allows to be set. If it can't meet that target then maybe the option to set that target shouldn't be available? However, as you say, the software encoder CAN hit the target pretty closely which says that there's a problem somewhere, IMO.
     
  20. Pete

    Pete Forum Admin Staff Member

    The software can't know in advance, that the source lacks enough detail to hit that target.
    Anyway, personally I think this is a non-issue - really not worth discussing.