[MEncoder-users] Terrible results with x264

[Grozdan]

On Thu, Dec 23, 2010 at 3:30 PM, Joseph Miller <josephcmiller2 at gmail.com> wrote:
> On Thu, Dec 23, 2010 at 9:18 AM, Grozdan <neutrino8 at gmail.com> 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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>>>> MEncoder-users at mplayerhq.hu
>>>> https://lists.mplayerhq.hu/mailman/listinfo/mencoder-users
>>>
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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?
>>
>
> Maybe if the devs would have mentioned that in the man page under the
> crf option or the qp option, I would have known.  I've always received
> very good results using qp 10-20.  Now that I know, I will use crf in
> the future.

First, x264 does NOT have a man page. Don't rely on man pages written
for mplayer to be always up to date for the external bits
Second, it is mentioned on many places like forums, mailing lists,
wiki's, irc, etc, etc. Each time someone brings that topic up, the
same conslusion follows. CRF should be used while QP should be avoided
unless you really have a good reason to use QP, which is most likely
for testing/debugging something.
Third, if you are switching to something knew and don't know in
advance what it offers, always do some digging. Don't just blindly
jump o it and use options without really understanding how they work
or what impact they may have

>
> -Joseph
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