Xvid Mencoder - output File too small (lower bitrate)

[grim1234]

I'm having some problems getting ffmpegx to produce an xvid avi from a dvd with a specific filesize. I've tried both the xvid mencoder and xvid ffmpeg options for the video. Some info on the video:

format - vob, ac3 audio.
length - 116min
resolution - 720x576, aspect 2.35:1
framerate - 25fps

Mencoder settings :

video:
640x272, crop 70,70,0,0
116min keep in 1400 mb, 25fps.
bitrate calculator gives = 1468 kbit/s
Qmin = 2
Qmax = 31
options = high quality, two-pass, trellis, bicubic scaling

audio :
192 kbit/s VBR, 4800, stereo.

This produces a file of size 1.12 gb, length 116min, video bitrate=1.1Mbps, audio=178kbit/s

This is 0.25gb too small! Why isn't it using the bitrate set by the bitrate calculator?

I understand the bitrate is a bit higher than needed for 'best', but I want to be able to set the bitrate and not have it change each time.

I've put the output of the i window below :

Encoding started on Tue Aug 21 10:58:32 BST 2007
FIXME:Hardenabling SSE and SSE2 without detection
MEncoder dev-CVS-060307-04:23-4.0.1 (C) 2000-2006 MPlayer Team
Mac OSX static build for ffmpegX
CPU: Intel  (Family: 6, Stepping: 6)
CPUflags: Type: 6 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2
success: format: 0  data: 0x0 - 0x5e879000
MPEG-PS file format detected.
VIDEO:  MPEG2  720x576  (aspect 3)  25.000 fps  7500.0 kbps (937.5 kbyte/s)
[V] filefmt:2  fourcc:0x10000002  size:720x576  fps:25.00  ftime:=0.0400
==========================================================================
Opening audio decoder: [liba52] AC3 decoding with liba52
Using SSE optimized IMDCT transform
AC3: 5.1 (3f+2r+lfe)  48000 Hz  384.0 kbit/s
Using MMX optimized resampler
AUDIO: 48000 Hz, 2 ch, s16le, 384.0 kbit/25.00% (ratio: 48000->192000)
Selected audio codec: [a52] afm: liba52 (AC3-liba52)
==========================================================================
xvid: using library version 1.2.-127 (build xvid-1.2.0-dev)
Opening video filter: [expand osd=1]
The selected video_out device is incompatible with this codec.
Try adding the scale filter, e.g. -vf spp,scale instead of -vf spp.
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [scale w=640 h=272]
Crop: 720 x 436, 0 ; 70
==========================================================================
Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
VDec: vo config request - 720 x 576 (preferred colorspace: Mpeg PES)
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
VDecoder init failed :(
Opening video decoder: [libmpeg2] MPEG 1/2 Video decoder libmpeg2-v0.4.0b
Selected video codec: [mpeg12] vfm: libmpeg2 (MPEG-1 or 2 (libmpeg2))
==========================================================================
MP3 audio selected
VDec: vo config request - 720 x 576 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
SwScaler: BILINEAR scaler, from Planar YV12 to Planar YV12 using MMX2
videocodec: XviD (640x272 fourcc=44495658 [XVID])
xvid: bitrate setting is ignored during first pass
xvid: par=0/0 (vga11), displayed=640x272, sampled=640x272
xvid: 2Pass Rate Control -- 1st pass
1 duplicate frame(s)!
Writing header...
ODML: vprp aspect is 16384:6963.
Writing header...
ODML: vprp aspect is 16384:6963.
Writing header...
1 duplicate frame(s)!
ODML: vprp aspect is 16384:6963.
Skipping frame!
Skipping frame!
Flushing video frames
Writing index...
Writing header...
ODML: vprp aspect is 16384:6963.
Video stream: 1312.542 kbit/s  (164067 B/s)  size: 1142627265 bytes  6964.360 secs  174111 frames
Audio stream:  177.979 kbit/s  (22247 B/s)  size: 154930080 bytes  6963.960 secs
MEncoder dev-CVS-060307-04:23-4.0.1 (C) 2000-2006 MPlayer Team
FIXME:Hardenabling SSE and SSE2 without detection
Mac OSX static build for ffmpegX
CPU: Intel  (Family: 6, Stepping: 6)
CPUflags: Type: 6 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2
success: format: 0  data: 0x0 - 0x5e879000
MPEG-PS file format detected.
Using SSE optimized IMDCT transform
VIDEO:  MPEG2  720x576  (aspect 3)  25.000 fps  7500.0 kbps (937.5 kbyte/s)
[V] filefmt:2  fourcc:0x10000002  size:720x576  fps:25.00  ftime:=0.0400
==========================================================================
Opening audio decoder: [liba52] AC3 decoding with liba52
AC3: 5.1 (3f+2r+lfe)  48000 Hz  384.0 kbit/s
AUDIO: 48000 Hz, 2 ch, s16le, 384.0 kbit/25.00% (ratio: 48000->192000)
Selected audio codec: [a52] afm: liba52 (AC3-liba52)
Using MMX optimized resampler
==============
xvid: using library version 1.2.-127 (build xvid-1.2.0-dev)
The selected video_out device is incompatible with this codec.
Try adding the scale filter, e.g. -vf spp,scale instead of -vf spp.
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [scale w=640 h=272]
Crop: 720 x 436, 0 ; 70
==========================================================================
Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
VDec: vo config request - 720 x 576 (preferred colorspace: Mpeg PES)
Could not find matching colorspace - retrying with -vf scale...
MP3 audio selected
VDecoder init failed :(
Opening video decoder: [libmpeg2] MPEG 1/2 Video decoder libmpeg2-v0.4.0b
Selected video codec: [mpeg12] vfm: libmpeg2 (MPEG-1 or 2 (libmpeg2))
==========================================================================
VDec: vo config request - 720 x 576 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
SwScaler: BILINEAR scaler, from Planar YV12 to Planar YV12 using MMX2
videocodec: XviD (640x272 fourcc=44495658 [XVID])
xvid: par=0/0 (vga11), displayed=640x272, sampled=640x272
xvid: 2Pass Rate Control -- 2nd pass -- bitrate=1468kbit/s
1 duplicate frame(s)!
Writing header...
ODML: vprp aspect is 16384:6963.
Writing header...
ODML: vprp aspect is 16384:6963.
Writing header...
ODML: vprp aspect is 16384:6963.
1 duplicate frame(s)!
Skipping frame!
Skipping frame!
Flushing video frames
Writing index...
Writing header...
ODML: vprp aspect is 16384:6963.
Video stream: 1186.340 kbit/s  (148292 B/s)  size: 1032762513 bytes  6964.360 secs  174111 frames
Audio stream:  177.979 kbit/s  (22247 B/s)  size: 154930080 bytes  6963.960 secs
Encoding completed on Tue Aug 21 13:17:08 BST 2007

[grim1234]

too complicated for you guys?

nevermind, i've had to resort to using gordian knot via parallels, took a little longer but at least the output was the same as the settings...

[exekutive]

Did you use the bitrate calculator AFTER setting your audio options?

[grim1234]

yes, bitrate calc after setting all options (video, audio, crop, options). The bitrate calculator gives the correct value anyway, it's just that the encoder doesn't encode at that bitrate. ie - set 1400 for xvid and get 1100 in the output video.

[Case]

For more control on the output file size, use the "DivX mencoder" preset, which allows for 3-pass encoding for bitrate control to match the desired file size.

[grim1234]

Yes, but I would like to use xvid as my video codec.

Why can't a 2-pass xvid encode at least use close to the selected bitrate?