2-pass xvid/mencoder problem

[buraku]

am trying to create a 2 pass XviD AVI from an mkv. i can do it with a single pass no problem. but when i try a 2 pass i get this message before the first pass starts.

Cannot open output file '/dev/null'.

here is the exact command line i am using.

"c:\program files\mplayer\mencoder.exe" "c:\temp\movie.mkv" -oac mp3lame -lameopts cbr:br=128 -ovc XviD xvidencopts pass=1 -o /dev/null

can anyone help me out? thanks in advance. i'm a noob to mencoder. would use vdub except the mkv is vfr and a/v won't sync.

[celtic_druid]

Windows doesn't have a /dev/null. Guess you could install some kind of linux distro. Could also try -o NUL

You might also want to consider VBR audio instead of CBR. Doesn't give you filesize predictablity, but it does give better quality.

[Scorpion King]

"c:\program files\mplayer\mencoder.exe" "c:\temp\movie.mkv" -oac mp3lame -lameopts cbr:br=128 -ovc XviD xvidencopts pass=1 -o /dev/null

My Linux isn't very good but /dev/null is a virtual file that can be written to, then the information is discarted. I don't understand why that line would be in there, but I can say it won't fly in Windows. That encoder looks very hard to learn, too hard for me...

can anyone help me out? thanks in advance. i'm a noob to mencoder. would use vdub except the mkv is vfr and a/v won't sync.

VD is the best program I know of to correct sync errors. Is the out of sync constant or does it get worse as the file plays. VD is also very good to test for sync problems in. If it plays good in VD then it is in sync, by my experiences that is.

Good luck.

[Ai Haibara]

Except VDub doesn't support MKV, and VDubMod's MKV support is outdated. Best bet is to demux the MKV streams with MKVExtractGUI (remember to install MKVtoolnix) and work with the resulting streams.

[buraku]

@celtic_druid:
thank you and i love you
@scorpion king:
if you can mux a vfr avc stream with ogg aud in vdub and not have any a/v sync issues, please let me know how. mencoder was the only thing i've found that can do it.
@ai haibara:
no need to separate streams before hand with mencoder.

[Scorpion King]

Ok buraku, I see the vfr (variable framerate) now. no wonder it won't sync.

Good luck.

[buraku]

ok, now i'm having another problem. is anyone else having problems using mencoder with dvp642? the vid i encode will play for a few seconds on the dvp then skip forward and the sound will go out of sync. but the avi i created plays fine on the comp.

[celtic_druid]

You could add add rofile=dxnhtntsc that way you at least get HT VBV settings. Not sure what else mencoder restricts as compared to VfW which restricts bframes to 1, forces packed bitstream, etc.

Also with stock builds of both mencoder and VfW you can't disable the use of N-VOP's with I understand the 642 doesn't like. What is so hard about simply redisplaying the previous frame though? I modified my XviD build to force no N-VOP's for DXN profiles. Could probably do the same thing for mencoder.

[Soopafresh]

Best bet is to demux the MKV streams with MKVExtractGUI (remember to install MKVtoolnix) and work with the resulting streams.


Thanks ! Just what I was looking for

[buraku]

one more question. i'm assuming the mkv i have is vfr. how do you tell? i heard something about looking at the timecode files. oh and is rofile=dxnhtntsc part of the -xvidencopts chain or the -vf chain?

[celtic_druid]

It is an XviD option. Quite possible that your problem is due to N-VOP's though in which case using a DXN profile won't help unless the mencoder build is modified. Basically by default if two frames are 100% identical then XviD will drop the second one. Guess mencoder could drop it first though.

I might patch my next mencoder builds to not use NVOP's for DXN profiles anyway.

[buraku]

one more question. i'm assuming the mkv i have is vfr. how do you tell? i heard something about looking at the timecode files.

[buraku]

does mencoder support batch encoding? if so, what command line do i use?

[celtic_druid]

Everything that is command line based supports batch processing. That is one of the pluses for command line apps.

[buraku]

thanks celtic. so what commands do i use for batch? i can't find it in the man page.

[celtic_druid]

That was my point. There is nothing specific to the app since command line apps support batch processing by their very nature.

for %%f in (*.avi) DO (mencoder.exe "%%f" ....)
etc.

[buraku]

i'm sorry celtic. but i don't have a lot of experience with command line.

so would this be an example of my command line?

for %%f in ("c:\movies\movie1.mkv,movie2.mkv,movie3.mkv") do ("c:\mencoder.exe" -oac mp3lame -ovc xvid -xvidencopts pass=1 -o nul)

[celtic_druid]

Well if you changed the above *.avi to *.mkv then it would scan the directory and run your mencoder commandline for each of them. You can use -o %%~nf.avi to have it output an avi of the same name. Otherwise if you have only 3 files you could just copy/paste your command and change the input/output.