[MEncoder-users] Terrible results with x264

[belcampo]

Grozdan wrote:
> On Thu, Dec 23, 2010 at 6:55 PM, belcampo <belcampo at zonnet.nl> wrote:
>> Grozdan wrote:
>>> On Thu, Dec 23, 2010 at 2:13 PM, belcampo <belcampo at zonnet.nl> wrote:
>>>> Joseph Miller wrote:
>>>>> On Wed, Dec 22, 2010 at 4:19 PM, Jason Cumiskey
>>>>> <jason.cumiskey at gmail.com> wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I have just started using x264 to encode my dvds.  I am going for
>>>>>> quality, not speed.  I am basing my -x264encopts off of the
>>>>>> recommendations from
>>>>>> http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-x264.html
>>>>>>
>>>>>> Here are the commands I issue (I am using 2 pass encode):
>>>>>> mencoder -dvd-device /dev/dvd1 dvd://1 -alang eng -aid 128 -oac mp3lame
>>>>>> -lameopts cbr:br=128:vol=7 -vf
>>>>>> pullup,softskip,crop=704:480:10:0,hqdn3d=2:1:2,harddup -ovc x264
>>>>>> -x264encopts
>>>>>>
>>>>>>
>>>>>> pass=1:bitrate=1400:subq=1:partitions=all:8x8dct:me=umh:frameref=1:bframes=3:b_pyramid=normal:weight_b:threads=auto
>>>>>> -o movie.h264
>>>>>>
>>>>>> # Pass 2
>>>>>> mencoder -dvd-device /dev/dvd1 dvd://1 -alang eng -aid 128 -oac mp3lame
>>>>>> -lameopts cbr:br=128:vol=7 -vf
>>>>>> pullup,softskip,crop=704:480:10:0,hqdn3d=2:1:2,harddup -ovc x264
>>>>>> -x264encopts
>>>>>>
>>>>>>
>>>>>> pass=2:bitrate=1400:subq=6:partitions=all:8x8dct:me=umh:frameref=6:bframes=3:b_pyramid=normal:weight_b:threads=auto
>>>>>> -o movie.h264
>>>>>>
>>>>>>
>>>>>> On pass 2, I change subq to 6 and frameref to 6 (as recommended in the
>>>>>> docs link above to speed up 1st pass and have higher quality for 2nd
>>>>>> pass).Can anyone see anything obviously wrong in my command chain?  The
>>>>>> resulting video is heavily pixelated and mplayer shows a bitrate of
>>>>>> 0kbps.
>>>>>>
>>>> FYI. multi-pass does NOT add any quality, it's only usefull when you have
>>>> a
>>>> hard-limit of size to obey. If you need to put the result on a
>>>> cd/usb-stick/DVD or something like that, then you can get max-quality
>>>> given
>>>> a fixed size.
>>>> If that is not the case use a qp=16-26 for very good to very acceptable
>>>> quality. You can leave out the bitrate when you choose Quality instead of
>>>> Size.
>>>>> My experience has been that the bitrate option either doesn't work
>>>>> very well, or I don't know how to use it.  Use qp=20 or so and you'll
>>>>> get good quality.  I have just started using the presets as well and
>>>>> preset=placebo gives very nice results.  Something like
>>>>> qp=20:preset=placebo:pass=1 then switching to pass=3 for 2nd encoding
>>>>> gives nice results and decent filesize.  I'm assuming that
>>>>> preset=[veryslow|slower|slow] would probably also give good results.
>>>>>
>>>>> -Joseph
>>>>> _______________________________________________
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>>>>
>>> Why are you both recommending qp? How many times do experienced
>>> encoders and the devs themselves need to mention that qp should NOT be
>>> used since it's "very dumb" compared to crf, which is the preferred
>>> option?
>> I would like to learn how dumb I am. My observations:
>> qp gives the most 'constant' quality, less quality variations than crf
>> qp encodes 'significantly' faster than crf.
> 
> Well, not to attack you or anything, but you're not very bright if you
> couldn't get the sentence above where the "very dumb" appears...
> Please re-read it again and think about whether it's about you or
> whether it's about the mode itself... Wait, I'll answer it for you.
> 
> IT'S ABOUT THE MODE ITSELF..... the qp mode is very dumb which means
> it can't do "intelligent" decisions on how much bitrate to allocate or
> not thus wasting where you could have come around with (much) lesser
> bitrate and couldn't see the difference if you compared the crf with
> the qp encode! The "very dumb" has absolutely nothing to do with you
> but apparently it was too hard to see.
> 
> And in the world of encoding, it's not only about "the most constant
> quality". There's an equally important factor or you wouldn't be
> encoding, unless if you want to shift formats for some reason. It's
> also about size. Why would you allocate, say, 1000kbps if you could
> have come around with 800 only on that specific frame and absolutely
> couldn't see the difference between the two?
> 
> about the being faster, I just asked Jason (x264 main dev). The only
> case where qp is faster than crf is if lookahead doesn't matter or
> isn't necessary. So why would you disable lookahead which improves
> quality just to gain a little bit of speed?
> 
> And finally, I'll repeat what Jason often mentions.... [quote] qp is
> only there for testing purposes. crf is the preferred mode for
> encoding if you go for constant quality. [/quote]
> 
>  Every knowledgeable self-respected encoder uses and recommends crf.
> If you think you're smarter than the devs or code itself, you're free
> to use whatever you believe (how unlikely it may be) provides better
> quality or speed.
Thanks a lot for the explanation. I do encode about 12 hours of 
source-material a day, have done a lot of testing/comparing and have 
found my 'ideal' mix of parameters. For me the order of importance is:
A. Quality
B. Speed
C. Size (indeed my preference results in a little less effective size)
> 
>>> Gee, people, stop giving bad advice or just keep quiet if you don't know
>>> :)
>>>
>>> About multipass, I do not have any issues with it nor get pixelated
>>> results
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