Mencoder : bug ?

[Sergejack]

G:\Installation\mencoder\mplayer2005.06.09.Athlon-XP>"mencoder.exe" "G:\X264\CPR
03.avs" -ovc x264 -o NUL: -passlogfile "mencoder-2pass.log" -x264encopts pass=1:
bitrate=162:keyint=999:min_keyint=250:frameref=15:bframes=16:b_adapt:b_pyramid:4
x4mv:i8x8mv:ratetol=2,0:qcomp=1,0:cplx_blur=0:qblur=0:scenecut=100:me=3
MEncoder dev-CVS-050609-00:54-3.4.4 (C) 2000-2005 MPlayer Team
CPU: Advanced Micro Devices Athlon MP/XP Thoroughbred (Family: 6, Stepping: 1)
Detected cache-line size is 64 bytes
CPUflags: Type: 6 MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 0 SSE2: 0
Compiled for x86 CPU with extensions: MMX MMX2 3DNow 3DNowEx SSE

85 audio & 199 video codecs
File not found: 'frameno.avi'
Failed to open frameno.avi
Option x264encopts: Unknown suboption min_keyint

Exiting... (error parsing cmdline)


:'(
x264.exe and now mencoder.exe...
what's wrong with me wanted to encode in h264 mp4 ? :'(

[Doom9]

it's keyint_min, not min_keyint.

I take it you have this commandline from megui? I'm afraid you've just discovered a bug. But.. the default of 25 works just fine.. your minimum and maximum GOP size is likely to result in less than ideal results.

[Sergejack]

it's keyint_min, not min_keyint.

I take it you have this commandline from megui?

indeed.

your minimum and maximum GOP size is likely to result in less than ideal results.

Shouldn't maximum gop size be high for very high (low bitrate) compression ?

As for the min gop size, I was affraid there could be too much IDR otherwise.

(Isn't Actually min and max gop size ideal settings related to the references frame number ?)

EDIT :
i8x8mv : 8x8mv

[berrinam]

Shouldn't maximum gop size be high for very high (low bitrate) compression ?

Yes, BUT this will only really have an effect if you have very long (ie longer than 10-second) scenes. It won't help compression anywhere else, because the codec will just insert I-frames, or even P-frames with each macroblock intra-predicted.

The downside of making it so high is the bad seeking times.


(Isn't Actually min and max gop size ideal settings related to the references frame number ?)
In what way?

[Sergejack]

Yes, BUT this will only really have an effect if you have very long (ie longer than 10-second) scenes. It won't help compression anywhere else, because the codec will just insert I-frames, or even P-frames with each macroblock intra-predicted.

The downside of making it so high is the bad seeking times.


In what way?

More intra frame in a gop make a wider gop have sens.
High compression justify less seekability.

[berrinam]

More intra frame in a gop make a wider gop have sens

I don't understand you, but I will take a punt. Are you saying that with a longer GOP you can use frames further away as references? That is right, but it only helps if the reference frame is similar, ie from the same scene.

Also, putting more intra frames into a gop largely counters any advantage you get by lengthening the GOP, because the intra frames are generally by far the largest.

One final thing -- longer GOPs need more computer resources (especially RAM, because the frames need to be stored in case they are referenced later in the GOP)

[akupenguin]

One final thing -- longer GOPs need more computer resources (especially RAM, because the frames need to be stored in case they are referenced later in the GOP)
No. The amount of memory used depends only on the 'frameref' option, which the standard doesn't allow to be larger than 16. A really smart encoder (not x264) could choose which 16 frames to keep, but that still doesn't affect decoding costs.