it has always been my credo that only facts and their explanations make sense
so while I fully admit a total and sincere commitment to 'demonstrate' that Batman (frontend preset to Mencoder and Libavc) would be hard work for providing "the end solution for real smooth frame rate conversion at 20fps" , still I totally disagree this would mean that VDub and XviD could not achieve at least the same "smooth frame rate conversion at 20fps " or even possibly improve ! as demonstrated here ...
testing both solutions at extreme is quite simple ; we know that the Meizu M6 is hard pressed not stuttering when reaching 500kbits or so. The challenge here will then be to use the Batman Q5 'high quality' 470kbits preset and see how it performs when compared to XviD at 470kbits ; in both case making use of a 20fps frame rate.
then we can see
1) Since Batman is supposed to provide for a (more) smoother frame rate it first should not stutter at all
2) *if* achieving smoother frame rate, it should not be at the expense of the image quality ; the later at least should equal or improve on XviD
having said this I choosed wise to pick up a very difficult file to encode ; the kind that combines lots of tiny details, no chroma noise, lots of motion , etc.. ; a very good candidate is the Elephants Dream open source project since it is available as a 1080p source . It is no small potatoes to try to get this into the tiny 2.4" screen of the meizu ; the later is 4/3 ratio so it was a good option to crop the source to 1440*1080 ; it is now HD but in 4/3 too and still 20 times more pixels in the picture resolution ; sure details will become very tiny and difficult to keep clean once scaled and encoded to 320*240 ! luckily the M6 screen helps for this with its 163 dpi
the movie source is here :
Elephants Dream » Download & Watch
take the so called 1920 HD version , curiously provided as MP42 codec ; now since peaks are as high as 50Mbits sometimes , it is the best option here as for image quality and detailed resolution ; a 815MB file though
Batman Q5 at 470kbps and 20fps is here :
MEGAUPLOAD - The leading online storage and file delivery service
VDbud and XviD at 470kbps and 20fps is here :
MEGAUPLOAD - The leading online storage and file delivery service
Soundtrack is mp3 128kbps stereo for both , and each is 45Mb in size ; for the Batman encode I choosed the latest (to date) 2008 available version , dated 5 february 2008 (three days ago)
Since there could be arguments on scaling I decided to scale first -the same- for both ; that is I made a Bicubic 320*240 and 20fps uncompressed source ; as for the codec choice I focused on Q5 and Q4 in Batman since they use of Libavc
so what happened ? once transfered in my M6, I found that :
1) the Batman file would stutter on some occasions . first at time 00:00:28 , then at time 00::05:16 (sometimes earlier at 05:11 instead ) , sometimes there will happen further stutter(s) soon after at time 05:17/18 , sometimes not ; later it will definitely stutter around time 00:05:41, and then again it may also be 05:39 and further 'replica' at 05;48 for instance. all these stutters indeed happen at high action scenes; just too normal so
2) the overall image quality was okay while obviously less detailed/sharp than the XviD encode
as for the VDub/XviD 470kbits file , it *never* stuttered at any moment ; the image is visibly superior too , with more details everywhere, thus even more challenging and difficult for the bit rate control !
As for the 'frame rate smoothness' I found both would provide same feeling for overall smoothness . It is quite a feat in both case given the 470k video bit rate is so close to the very maximum that brave little M6 can cope with ! now while the Vdub/Xvid encode got rid of stuttering here , I definitely would not recommend using such bit rate anyway. The screen size of the M6 is quite small and at 163dpi it does 'forgive' many artefacts ; so (again imho) keeping the bit rate 100kbits lower would not make such a visible difference . In Batman, for instance, I tried the Q4 preset (350kbits) and found it indeed visibly a bit inferior but reasonably not so different from Q5 anyway , while then gone are stutters with Q4
sure XviD is a difficult beast to take on a leash but it still can outperform any other solution !
Indeed I felt challenged to try and push XviD always a bit upper ( more than 500k average that is) but soon it then too started to stutter ; here is the typical XviD bit rate distribution then , which indicates it is on a tight-fast leash anyway
; now this is for sure a difficult movie for the RC , with a 10% change in the RC parameters making a 15 to 20% change in size
the tricky thing here (at 515k average) was that while it would stutter 'only' on two occasions ... it was on two 'average' sized frames not overshoot ....heck !! but since it was at times roughly similar to Batman Q5 stutters , this would still keep some logic here
rate control is quite good but Q5 will not achieve 470k average which should explain for the stutters ; ( see above a typical 515k VDub/Xvid bit rate gfx for similar appreciation ) ;
as mentioned Batman in its Q4 350kbps preset was okay with no stuttering but at the expense of some inferior image ; overall here is the typical Batman bit rate distribution for (any) Libavc (here Q4) ;
what is the more questioning here remains the 'lack' of I Frames where there should preferably be ; instead the Libavc codec manages many scene changes with P frames (of roughly similar size to I frame anyway) . I had noticed this with much more evidence in the so called "Batman Demo" movie ( the short LOTR movie) where obviously there lacks many I frames at full scene changes ; just play this movie either on the M6 or more conveniently on your PC and wach the bit rate distribution graph ; I frames are marked as red and in many occasions there should be one at a scene change . It is no obligation per se but then the drawback is that it will take a few consecutive P frames to achieve a 'neat' complete scene change . Luckily on the M6 this stays largely not much noticeable but if you choose a PC player in full screen mode you will see this ( mostly background details which are not set clean at once as with a sole I frame)
the bit rate graph indicates a slow(er) rate control which is not a bad thing per se with the M6 , but it definitely will/can come to fail on more difficult movies than this LOTR 'demo' , which is composed of rather static laaaarge figures filling the screen , little action, rather few details, etc..well easy to encode that is.
difficult to find more simple , no ? still there exists large VBR peaks which luckily get to be played here , quite possibly due to slow rise and decay , combined with few action, scene changes, etc.. ; anyway the bit rate control remains very questionable here ! I understand it is a "demo" ...
here is the link for the original Batman Demo movie :
RapidShare: 1-Click Webhosting
don't get me wrong , I find Batman a valuable and useful tool , especially since it uses of Mencoder and mainly Libavc ; with a bit more experimentation the later may quite possibly challenge or even improve on XviD here -- that is only as for use with the M6 ; who knows ! so yes Batman deserves kudos anyway for providing *M6* easy encodes ( otherwise the debate XviD vs Libavc is closed in favor of XviD)
since I "l
ost all dignity" making such analysis and comments , or that "
I dont' know what I am talking about" , or other kinda nice things from (..) , I simply let facts speak for themselves ; now and in the future ; no flame , facts , that's all
as facts ...take a look at what the HDX4 site dares provide as a 320*240 encode for PSP ; they for sure did not care much about all these encode matters ! the iPod file version is as bad either with peaks reaching 6Mbits ; it is quite probably a Q based fast encode and it is then interesting to see where really difficults scenes are
( such 'hidden' one is... the rolling credits at end , where no zone setting was used ( as for file size) in both Vdub/Xvid and Batman ; graphs speak for themselves )
http://80.190.241.27/hdx4/elephants_dream/ed_psp.mp4
http://80.190.241.27/hdx4/elephants_dream/ed_ipod.mp4
bit rate gfx of the PSP encode :
http://img178.imageshack.us/img178/1...hantpspgc6.jpg
the very sad point is that by sunday I will have nomore M6 ! I (stupidly) decided to sell it a few days ago and since I gave my word I will deliver it tomorrow or sunday ; I already miss it a lot ; and it's again all the Baman's fault
) without this episode I would have let it go without this hard work at tackling the best out of this little beauty ; I already look for another one in sell/buy forums !! but I am worried about the screen 'issue'...
http://www.meizume.com/43777-post5.html
http://img519.imageshack.us/img519/4...2300004pj6.jpg
well other '
dunno what I am talking about' gossip , I guess
so here it is , and enjoy Meizu
White M6 8gb from JTC Electronics
; while I doubt it anyway
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