Mencoder problem [Cannot initialize muxer]

Not sure where exactly to post, so putting it here. I have a problem using mencoder to convert files from other formats to flv.

Heres a snippet from an attempt to run mencoder: [~/video]# mencoder 48208.mp4 -o 48208.flv -of lavf -oac mp3lame -lameopts abr:br=56 -ovc lavc -lavcopts vcodec=flv:vbitrate=800:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 -srate 22050 -vf harddup
MEncoder 1.0rc1-4.1.2 (C) 2000-2006 MPlayer Team
CPU: Intel(R) Xeon(R) CPU           E5310  @ 1.60GHz (Family: 6, Model: 15, Stepping: 7)
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

98 audio & 216 video codecs
success: format: 0  data: 0x0 - 0x170bd4d
ISO: File Type Major Brand: ISO/IEC 14496-1 (MPEG-4 system) v2
Quicktime/MOV file format detected.
Warning! pts=6845000  length=6845586
Warning! pts=20125696  length=20127702
VIDEO:  [avc1]  522x314  24bpp  15.000 fps    0.0 kbps ( 0.0 kbyte/s)
[V] filefmt:7  fourcc:0x31637661  size:522x314  fps:15.00  ftime:=0.0667
Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
AUDIO: 44100 Hz, 2 ch, s16le, 53.6 kbit/3.80% (ratio: 6697->176400)
Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio) decoder)
** MUXER_LAVF *****************************************************************
If you wish to use libavformat muxing, you must ensure that your video stream
does not contain B frames (out of order decoding) and specify:
    -lavfopts i_certify_that_my_video_stream_does_not_use_b_frames
on the command line.
REMEMBER: MEncoder's libavformat muxing is presently broken and will generate
INCORRECT files in the presence of B frames. Moreover, due to bugs MPlayer
will play these INCORRECT files as if nothing were wrong!
Cannot initialize muxer.

Any attempts end at the “Cannot initialize muxer.” line. Any ideas what may be going on? Thanks for any pointers!

I merely use Flash™’s Adobe Media Encoder and that takes care of any problems. If you’re using a different product, I’d recommend using their troubleshooting pages or forum.

On the other hand, we MAY have a member who’s experienced this, too, so please check back.



Might be worth trying to update mencoder, there are newer versions available. You could also try ffmpeg which has similar functionality but generally is more verbose in error reporting.