[MEncoder-users] Re: Re: new doom9 codec comparission (submission)

Doom9 Feedback Hotline feedback123 at doom9.org
Mon Dec 19 14:14:17 CET 2005

>I smell something buggy... Have you been using ffdshow to encode all

Of course not, I'm always using the mencoder build Corey told me to use. I 
created a raw file with mencoder (-of rawvideo), then put that in an AVI 
with mencoder -ovc copy), and that file just cannot be opened via VfW. The 
alternative was taking the mp4box muxed MP4 file, extract the video stream 
to AVI with mp4box, cut that via VfW (VirtualDub) - that's the one mplayer 
cannot handle, VLC has no problem with either.

>and my reply was just to show this to be false, as such comments are
>making lavc look bad to who reads this

This is where you go wrong. You can disagree with my findings, that's your 
prerogative, but claiming they are false is just outrageous.. you do not 
have my visual system so how on earth can you claim that my findings are 
false? Given the exact same content and the same playback mechanism, you 
might rate things differently, and that's perfectly okay and the reason why 
I'm so meticulous in putting all information I think is necessary to 
reproduce a test in the comparison.. so you can see with your own eyes and 
draw your own conclusions. A metrics comparison can be right or wrong 
because somebody screwed up in the technical part (not taking into account 
frame delays introduced by B-frames for instance, duplicating frames to make 
the length of two encoded files match, screw up the statistics by 
calculation errors, etc), but those points are all moot for a subjective 
comparison - in such case, right or wrong is literally a matter of point of 
view. Unlike some other people here I do not claim to have the absolute 
truth, I can only give what I see, it's up to everybody reading the 
comparison to judge for themselves and trying to reproduce the results to 
verify if they would come to the same conclusion. If they do, they could've 
saved themselves a lot of effort, if they didn't, they might both have 
learned something knew, and can be sure that now they make the right choice 
for themselves.

>also note iam also always interrested in bugreports which would show
>examples where my pp code is worse, if noone sends us bugreports we
>cant know about the issues and cant fix them ...

How can you say something is broken? As a fellow programmer, I wouldn't dare 
call somebody broken until I have good reasons to make such a claim. I can 
only point out that if you decode the xvid clip with ffdshow and then with 
the xvid dshow filter (deblocking turned on in both cases), the results of 
the latter look more visually pleasing to me. That's a subjective call, I 
cannot say either one is broken or does it better, just that one looks 
better to me than the other. That's all the info you need to try and 
reproduce.. I'll be interested to hear your findings. And please note, that 
this is about DirectShow filters so you have no choice but to do this on a 
Windows box.. using mplayer just isn't the same.

>no double blind tests?

You have two samples, feel free to do that on your own. I'm reasonably 
confident that you cannot argue that amount of a difference away. And it 
clearly says in the qualification that I cannot tell the difference between 
lavc and xvid in the still scenes. That is, they are different but I cannot 
make the call which one looks better.. they just look different.

Finally, I need to say something: no other participant has ever give me that 
amount of grief. I find it very unprofessional of anybody to try and twist 
things to their favor by trying to force a certain decoder (they probably 
know to be superior and make other codecs look worse?) via bully tactics, 
and by unwarranted attacks on my testing methods. In five years of codec 
testing, this has not happened a single time before (I shudder at the 
thought of looking up discussions that ensued after I tested libavcodec last 
time). All participants, being open source teams or large commercial 
entities, have always been courteous, and never destructive, even when faced 
with unfavorable results, at times even mistakes of my own that would have 
given them plenty of reasons to raise hell. They might respectfully disagree 
with my findings, which is everybody's right, but what I'm experiencing here 
goes way beyond that.

I have invested a considerable amount of additional time to explain many 
issues, gone to considerable trouble of taking extra screenshots and posting 
samples, just to be brushed off with impolite if not borderline arrogant and 
snippish comments. I have not even enforced the two day period that the 
comparison rules give to fix settings in case something goes wrong (which it 
did in case of Snow). I couldn't even phantom what a comparison would look 
like if I adopted the same kind of behavior that I had to experience here, 
at the very least I'd immediately disqualify the participant. But at this 
point I have a hard time imagining ever putting myself through this again in 
the future. There are a lot of other codecs out there, and a lot of people 
that have no problem accepting if somebody does not share their opinion.

Good bye

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