[MEncoder-users] Encoding h264 mov 50 fps to flv - loosing of frames and seconds

[Raffaele Gambelli]

Hi all,

I'm quite a newbie of video editing and I would like to receive your 
opinion about my problem.
My app internally makes use of mencoder to convert video of any formats 
to flv videos.

My problem is that output video is less than original of 23 seconds, so 
the original is 3.53 and flv is 3.30

Here there are input video characteristics, and then my command line 
statement:

Format : MPEG-4
Format profile : QuickTime
Codec ID : qt
File size : 91.0 MiB
Duration :*3mn 53s *
Overall bit rate : 3 269 Kbps
Writing library : Apple QuickTime

*Video*
ID                               : 2
Format                           : *AVC*
Format/Info                      : Advanced Video Codec
Format profile                   : Main at L2.1
Format settings, CABAC           : No
Format settings, ReFrames        : 2 frames
Codec ID                         : avc1
Codec ID/Info                    : Advanced Video Coding
Duration                         : 3mn 53s
Bit rate mode                    : Variable
Bit rate                         : 1 853 Kbps
Width                            : 512 pixels
Height                           : 288 pixels
Display aspect ratio             : 16:9
Frame rate mode                  : Constant
Frame rate                       : *50.000 fps*
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits

*Audio*
ID                               : 1
Format                           : PCM
Format settings, Endianness      : Little
Format settings, Sign            : Signed
Codec ID                         : sowt
Duration                         : 3mn 53s
Bit rate mode                    : Constant
Bit rate                         : 1 411.2 Kbps
Channel(s)                       : 2 channels
Sampling rate                    : 44.1 KHz
Bit depth                        : 16 bits
Stream size                      : 39.3 MiB (43%)
Language                         : English

*/usr/bin/mencoder* /test/test02_h264.mov -o 
/tmp/no_meta_lXYcUz_test02_h264.mov.flv -of lavf -vf 
scale=0:0,expand=0:0 -oac mp3lame -lameopts abr:br=56 -srate 22050 -ovc 
lavc -lavcopts vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3

The resulting video is 3.30 rather than 3.53 and in fact, this 
difference is really visible and ugly when playing video.

My mencoder version is *SVN-r1.0~rc3+svn20090426-4.4.3* and I'm running 
on Ubuntu 10.04

I would like to receive some hints about flv generation of these kinds 
of video.
*Consider that I tried with many others h264 video and they always 
worked fine*, the only difference is the fps, all these successfully 
converted video have less than 30 fps while the above described video 
has 50 fps.

Thanks in advance and best regards

-- 

Raffaele Gambelli