Does 2-Pass Encoding Really Make a Difference (HandBrake)

Discussion in 'Apple TV and Home Theater' started by RRutter, Oct 21, 2008.

  1. macrumors 6502

    Joined:
    Jan 1, 2008
    Location:
    El Paso, TX
    #1
    2-Pass encoding really takes up so much more time in converting in HandBrake. It takes so much time - so I wanted to know; does 2-pass encoding really make much of a difference in the quality of the movie? Thanks.
     
  2. macrumors regular

    Joined:
    Feb 15, 2007
    #2
    The answer is..
    Of course it does!

    But this all depends on the quality you are encoding in the first place. However, I find you can 2 pass a lower bitrate and get equal results to a higher bit rate depending on your settings. However, if you are just ripping at AppleTV preset there is hardly any point..
     
  3. thread starter macrumors 6502

    Joined:
    Jan 1, 2008
    Location:
    El Paso, TX
    #3
    I ripped off some TV shows from Futurama Season 4 (yes, I own it) and was wondering if I should do 2 pass encoding on that.. I'd rather not because of the time it takes..
     
  4. macrumors 68000

    JonHimself

    Joined:
    Nov 3, 2004
    Location:
    Toronto, Ontario
    #4
    I have absolutely nothing to back up my opinion but I have read numerous threads on the issue. Hopefully someone will give you a better answer, but...
    As far as I know it *does* make a difference on either the quality OR the size of the file. The problem is that I don't think the picture quality difference is *that* noticeable and with the declining pricing of hard drives, the space you save might not be worth it.
    Personally I use the two-pass encode out of habit. I don't think I've ever read anything that has solid evidence of the difference in quality be negligible so I will continue to use the two-pass until I am able to be convinced the difference isn't worth it. (I don't mind using the extra time because I just let it run overnight)
     
  5. thread starter macrumors 6502

    Joined:
    Jan 1, 2008
    Location:
    El Paso, TX
    #5
    But for someone that doesn't want to leave it on all night (me) could I just turn off 2-pass encoding?
     
  6. macrumors 68000

    Joined:
    Jan 26, 2006
    Location:
    Whitehouse, OH
    #6
    Sure, no one is holding a gun to your head. I doubt you'll notice the difference. I gave up on two-pass a long time ago and went with CRF, but that is another discussion entirely.

    I will say, if you're encoding Futurama, use the new development snapshot and enable detelecine and the decomb filter. Trust me, it is worth it.
     
  7. thread starter macrumors 6502

    Joined:
    Jan 1, 2008
    Location:
    El Paso, TX
    #7
    Yes I have the latest one. I already enable detelecine, haven't done decomb filter, but will. Thanks! If you use HandBrake right, it is in fact much better than the used to cost money VisualHub, until they went down.
     
  8. macrumors 68000

    JonHimself

    Joined:
    Nov 3, 2004
    Location:
    Toronto, Ontario
    #8
    I've read threads of about CRF with little understanding. Is there a way you can sum up why I should (and even why I shouldn't) use CRF as opposed to picking a bit rate (I use 3000)? I understand the premise of CRF but most of the discussions I've read just have both sides arguing why the other is no good.
     
  9. macrumors 6502

    Joined:
    Sep 5, 2003
    Location:
    Christchurch, New Zealand
    #9
    Should: Because you get to choose the quality of the encode, at 60% with the new snapshot it is pretty much identical to source. It is single pass, and you can use bitrate limiters to prevent bitrate spikes above what your player can handle.

    Shouldn't: Because some noisy/grainy films (art films etc) take a lot of bits to encode and get that same quality as the original, and that will push up the file size quite a bit. Average Bit Rate (ABR) will give you a predictable filesize, however on action packed movies that require a high bitrate quality will suffer if you have arbitrarily chosen a lower bitrate than that movie requires.

    So in summary:

    CRF: Predictable quality, unpredictable filesize
    ABR: Unpredictable quality, predictable filesize

    The reason that 2-pass for ABR is good is that it allows the compressor to figure out in advance of how many bits it needs in order to meet the bitrate targets that you have set. Which means it is less likely to run out during an action scene and present you with overcompressed video.

    Cheers, Ed.
     
  10. macrumors 68000

    Joined:
    Jan 26, 2006
    Location:
    Whitehouse, OH
    #10
    Exactly what eddyg said. :cool:
     
  11. thread starter macrumors 6502

    Joined:
    Jan 1, 2008
    Location:
    El Paso, TX
    #11
    Same here. :D:D:D:D:D:D
     
  12. macrumors 6502

    Joined:
    Sep 5, 2003
    Location:
    Christchurch, New Zealand
    #12
    Note that some modern movies only require about 1500kbps to achieve 60% CRF. That means that if you were using ABR, at say 2500kbps, you are wasting 1000kbps on unnecessary quality.

    So the unpredictable filesize argument for CRF goes both ways, you may end up with (and often do) a file a lot smaller than with ABR at the same quality.

    Cheers, Ed.
     
  13. thread starter macrumors 6502

    Joined:
    Jan 1, 2008
    Location:
    El Paso, TX
    #13
    I do 1500kbps on all Movies/TV Shows.
     
  14. macrumors demi-god

    xraydoc

    Joined:
    Oct 9, 2005
    Location:
    192.168.1.1
    #14
    I tend to use a slightly modified AppleTV setting (modified to play on the iPhone/touch) with single pass at 1500bps and strict anamorphic scaling for most movies. For CG animation, I will turn it down to 1200bps since typically the pictures so clean to begin with. I've been very happy with the results on my two TVs (a 55" LCD 720p rear-projection TV and a 42" 720p plasma). Encodes for a 100 minute DVD tend to float around 1.3-1.4GB. For some of the big action movies (Iron Man, Indiana Jones) I'll do 1700bps and a two-pass encode.

    These encodes however do not play on 5G iPods for what ever reason. Doesn't really matter to me much, so I haven't bothered to figure out why. As long as they work on the AppleTV and the iPhone/iPod touch.

    I haven't tried playing any of these on my 105" Optoma 720p projector, but I suspect they'd look ok for non-HD source material. For this screen, its either HD-DVD, Blu-Ray or the original DVD via an upscaling player.

    I did a couple James Bond flicks at a fairly high bit rate which ended up with files sizes of around 2.5GB. Don't see any picture improvement over my current method except for the smaller file sizes (smaller by a full gigabyte!).

    I did one the other day using the iPod High-Rez preset and a bit rate of 1500bps and strict anamorphic scaling. Came out very nicely I think. I'm unable to see any difference on my computer's 24" display.
     
  15. macrumors newbie

    welzofstel

    Joined:
    Sep 12, 2006
    Location:
    Dallas, TX
    #15
    If you don't want to read all of this, the summary of it all is at the bottom. I get wordy. Sorry.


    I have been testing this 2-Pass thing out myself. I am currently converting my whole DVD collection to AppleTV using the Legacy Preset with 2-Pass on movies I really like, for example, "Blade Runner - Final Cut" and no 2-pass on movies I don't like so much like "AVP - Alien VS Predator". I was watching the latter and the sequel recently and I was actually amazed just how good they looked.

    Now, I am still using Sony 36" HD-CRTs. One in the living room and one in the bedroom each with AppleTV that I stream the content to. No syncing. I do not have flat screens as these TVs are still in great working conditions and neither is more than five or six years old. The second one is only 3 years old. They are big and clunky but, the pictures are just beautiful. I don't know if that makes a difference as I'm sure most everyone here has a flat screen of some type.

    I have tested out a few different encoding settings and I have decided to stick with the AppleTV Legacy with 2-pass but, I have found that newer movies just look good without 2-pass. When I encoded "Aliens" filmed in 1986 and "Akira" filmed in 1988 without 2-pass, I noticed quite a bit of pixelation and artifacts. I ran them through again and there was a noticeable improvement but, I went back and watched the DVDs and the fact is, if it looks bad on the DVD, it's gonna look bad on AppleTV. This was evident when I encoded "Alien: Resurrection" filmed 10 years later. Looked MUCH better than "Aliens".

    SUMMARY:
    I will still use AppleTV Legacy preset with 2-pass for movies I really like but, I can say that, newer movies still look great without 2-pass from my experience and testing. There is absolutely no change in file size but some movies do have a significant improvement in resolution. I don't have much time to tinker with settings as I have a lot of DVDs to go through.

    -F.
     
  16. macrumors 68020

    Joined:
    Mar 27, 2003
    #16
    which is why all relevant hb presets moved to crf (constant quality), which renders the whole 1 pass vs. 2 pass debate obsolete.
     
  17. macrumors newbie

    welzofstel

    Joined:
    Sep 12, 2006
    Location:
    Dallas, TX
  18. macrumors 68020

    Joined:
    Mar 27, 2003
    #18
    Don't be :) . I was just pointing out another ( and frankly better imo ) alternative. The x264 devs all use it afaik and by and large, unless you have a device with extremely narrow bitrate limits ( which would pretty much only be the 5G iPod now) constant quality as defined in hb 0.9.3's presets is a far better rate control method in general. Which has the added bonus of only working in single pass mode. Again, just my .02.
     
  19. macrumors newbie

    welzofstel

    Joined:
    Sep 12, 2006
    Location:
    Dallas, TX
    #19
    Well, that is really helpful to know. I just started using Handbrake a few months ago since I just got my AppleTVs and I am always looking for the best advice on an efficient and "quick" method of encoding.

    It's a bit difficult to sift through all the posts.

    Thank you.

    -Frank
     
  20. macrumors 68020

    Joined:
    Mar 27, 2003
    #20
    Fair doos. I can tell you that several hb dev's use atv's as one of their main playback target platforms. The built in atv presets in hb are pretty much optimized for the atv at the time of that public release. Having said that there is one issue on HB 0.9.3's atv preset which was realized *after* 0.9.3 came out. In the Advanced settings (which is where most of the real magic happens) weightb=1 should be removed from the option string. It causes stuttering and dropped frames on the atv with some sources. It was realized after further testing of the atv after the preset was written for 0.9.3 and released. Other than that the atv preset for 0.9.3 should give you a very nice quality across sources.
     
  21. macrumors G4

    Chundles

    Joined:
    Jul 4, 2005
    #21
    I can't get any of those new CRF presets to work on any of my stuff. The movies copy over to the iPhone but it just says that the movie format is "unsupported."

    When I'm going to be watching it on my computer and my iPod I'll rip it at 2000kbps, H.264, 2 pass and loose anamorphic with the vertical res as close to 480 as it will go but no higher.

    Looks awesome on my computer and great on the iPhone too. Earlier iPods can't play the anamorphic stuff though.

    If it's only going to be on my iPhone I'll rip at 700kbps, 480xwhatever, H.264 and just one pass. Looks perfectly fine on the iPhone and takes up much less room, usually around 700MB.

    Anyone got any ideas about why the new presets aren't working?
     
  22. macrumors 68020

    Joined:
    Mar 27, 2003
    #22
    Presets > Update Built-In Presets
     
  23. macrumors G4

    Chundles

    Joined:
    Jul 4, 2005
    #23
    Done that many times - still no dice.
     
  24. macrumors 68020

    Joined:
    Mar 27, 2003
    #24
    Would have to see an activity log to tell you more ...
     
  25. macrumors G4

    Chundles

    Joined:
    Jul 4, 2005
    #25
    All good mate, I haven't updated in a while so maybe that's the ticket. I'll try it and if it works then all well and good.

    I wasn't aware that the presets are updated constantly.
     

Share This Page