[MEncoder-users] flv with vp6 codec too fast after encoding

[Bram]

Hi,

I have encoded several FLV files with VP6 codec in them. They all
transcoded just fine, with the correct fps. I updated mencoder/mplayer
to the latest version from svn as we speak.

Now, however, I've run into an flv file which always runs too fast when
transcoded using mencoder. I've tried the vp6 and ffvp6f video
codecs, and the lavfpref demuxer (others don't work at all), but it just
won't work. Playing back the file using mplayer works fine though.

I've put up the first 5MB of the file on my site here:

http://bram.name/~brama/test_mencoder_too_fast.flv

Sample basic mencoder command:

/mencoder "$IN" -o "$OUT" -vc ffvp6f -demuxer lavfpref -oac mp3lame -ovc xvid -xvidencopts bitrate=600

or

/mencoder "$IN" -o "$OUT" -vc vp6 -demuxer lavfpref -oac mp3lame -ovc 
xvid -xvidencopts bitrate=600 -vf flip

I'm thinking the detected fps of 29.97 is bogus. If I add '-fps 15' to
the mencoder cmdline, the speed is more like that at which mplayer plays
back the file. However, mplayer also reports a detected fps of 29.97
during playback. Specifying -fps <anyvalue> on the mplayer command line
doesn't change anything though.

One thing that strikes me as peculiar is midentify's output. It lists
ID_AUDIO_* information twice. The first time, it detects 2 audio
channels. The second time the entries appear, the number of channels
suddenly is 1. May this have something to do with it? I've tried with
-oac copy, but that didn't change anything. midentify output:


ID_VIDEO_ID=0
ID_AUDIO_ID=1
ID_FILENAME=test_mencoder_too_fast.flv
ID_DEMUXER=lavfpref
ID_VIDEO_FORMAT=VP6F
ID_VIDEO_BITRATE=0
ID_VIDEO_WIDTH=720
ID_VIDEO_HEIGHT=480
ID_VIDEO_FPS=29.970
ID_VIDEO_ASPECT=0.0000
ID_AUDIO_FORMAT=85
ID_AUDIO_BITRATE=64000
ID_AUDIO_RATE=44100
ID_AUDIO_NCH=1
ID_LENGTH=468.03
ID_SEEKABLE=1
ID_VIDEO_CODEC=ffvp6f
ID_AUDIO_BITRATE=64000
ID_AUDIO_RATE=44100
ID_AUDIO_NCH=2
ID_AUDIO_CODEC=mp3



Best regards,
Bram