[MEncoder-users] help: first frame is no key frame

[belcampo]

Sangeetha M wrote:
> I have captured video using mencoder. I have used ffmpeg to cut the
> video. When I cut the clips, some clips are showing error "first frame
> is no key frame". For that clips, the starting sec the video is blurred.
> 
>  
> 
> Mencoder command:
> 
>  
> 
> mencoder -tv input=2:width=768:height=576 tv://0  -oac lavc -ovc lavc
> -of mpeg -vf scale=720:576,pp=ci,harddup -srate 24000 -af
> lavcresample=24000 -lavcopts
> vcodec=mpeg2video:vbitrate=500:keyint=15:vstrict=0:acodec=ac3:abitrate=6
> 4:aspect=4/3 -ofps 25 -o d:\movie.mp4
> 
>  
> 
> ffmpeg command to cut the video:
> 
>  
> 
> ffmpeg -ss 40 -t 10 -i d:\movie.mp4 -s 320x240  -b 500k -r 25 -vcodec
> mpeg4 -acodec libfaac -ab 64k -ac 1 -ar 24000 -vol 1024 -qscale 1
> -benchmark -y d:\clips\clip1.mp4
> 
>  
> 
> How to solve this?
I think by doing some math
keyint=15
keyframes are at 15, of 25frames, intervals, being 15*1/25=0.6secs. So 
your -ss # has to be a multiple of 0.6 seconds
> 
>  
> 
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