[MEncoder-users] Trouble with enabling B-frames for DVD-compliant MPEG-2

[Francois Visagie]

Dear List,

I am using MEncoder 1.0rc1-3.4.2 on Windows for making DVD-compliant
encodes. The trouble I'm having is that it crashes when I enable B-frames
with vmax_b_frames<>0. By process of elimination, the only way to prevent it
from crashing is to remove from -lavcopts both vrc_buf_size=1835 and
vrc_maxrate=9800, which are necessary for DVD compliance.

The command line I'm using - with a nice high bitrate due to the shortness
of the movie - is:

mencoder %1 -aspect 4/3 -mc 0 -noskip -vf hqdn3d=2:1:2,harddup -ovc lavc
-oac lavc -lavcopts
aspect=4/3:ildct:ilme:keyint=15:vbitrate=7345:vb_strategy=1:vcodec=mpeg2vide
o:vmax_b_frames=1:vpass=1:vrc_buf_size=1835:vrc_maxrate=9800:vstrict=0:acode
c=ac3:abitrate=128:psnr -of mpeg -mpegopts format=dvd:tsaf -o %OUTPUT%

The bitrate has no influence on this behaviour - either I have to disable
B-frames, which hurts quality, or I have to remove the above two -lavcopts
which breaks DVD compliance.

When MEncoder crashes in this way, it doesn't do it very informatively. The
display shows:
---
MEncoder 1.0rc1-3.4.2 (C) 2000-2006 MPlayer Team
CPU: Intel(R) Pentium(R) M processor 2.00GHz (Family: 6, Model: 13,
Stepping: 8)

CPUflags: Type: 6 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 0 SSE2: 0
Compiled with runtime CPU detection.
c:\windows\fonts\arial.ttf doesn't look like a bitmap font description,
ignoring
.
Cannot load bitmap font: c:\windows\fonts\arial.ttf
success: format: 0  data: 0x0 - 0xf205000
AVI file format detected.
AVI_NI: No video stream found.
libavformat file format detected.
VIDEO:  [dvsd]  720x576  0bpp  25.000 fps  28800.0 kbps (3515.6 kbyte/s)
[V] filefmt:35  fourcc:0x64737664  size:720x576  fps:25.00  ftime:=0.0400
==========================================================================
Opening audio decoder: [pcm] Uncompressed PCM audio decoder
AUDIO: 48000 Hz, 2 ch, s16le, 1536.0 kbit/100.00% (ratio: 192000->192000)
Selected audio codec: [pcm] afm: pcm (Uncompressed PCM)
==========================================================================
PACKET SIZE: 2048 bytes, deltascr: 43885
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [harddup]
Opening video filter: [hqdn3d=2:1:2]
==========================================================================
Opening video decoder: [dshow] DirectShow video codecs
Decoder supports the following YUV formats: YUY2 UYVY
Decoder is capable of YUV output (flags 0x9)
VDec: vo config request - 720 x 576 (preferred colorspace: Packed YUY2)
[PP] Using codec's postprocessing, max q = 4.
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
VDec: using Packed YUY2 as output csp (no 0)
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
SwScaler: reducing / aligning filtersize 1 -> 4
SwScaler: reducing / aligning filtersize 1 -> 4
SwScaler: reducing / aligning filtersize 1 -> 1
SwScaler: reducing / aligning filtersize 9 -> 8

SwScaler: BICUBIC scaler, from yuyv422 to yuv420p using MMX2
SwScaler: using 4-tap MMX scaler for horizontal luminance scaling
SwScaler: using 4-tap MMX scaler for horizontal chrominance scaling
SwScaler: using 1-tap MMX "scaler" for vertical scaling (YV12 like)
SwScaler: 720x576 -> 720x576
videocodec: libavcodec (720x576 fourcc=3267706d [mpg2])
VideoDecoder::SetExtAttr: registry failure
Selected video codec: [qdv] vfm: dshow (Sony Digital Video (DV))
==========================================================================
Limiting audio preload to 0.4s.
Increasing audio density to 4.
Writing header...1f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]
INITV: 0.200, 0.160, fps: 25.000
Pos:   0.1s      3f ( 0%)  0.00fps Trem:   0min   0mb  A-V:0.000 [0:0]
---

At which point the Microsoft "mencoder.exe has encountered a problem and
needs to close.  We are sorry for the inconvenience." error dialogue is
displayed.

I've searched this list's archives but found no posts that link the use of
these options with B-frames as a cause of crashing.

Does anybody have a fix or work-around to suggest for this, please?
Alternatively I'd be happy to post a full bug report with detailed stack
dump from that Microsoft dialogue, just let me know.

Thanks kindly,
Francois





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