[Libav-user] ffmpeg and JM I_Frame nonconformity

amir.rouhi at rmit.edu.au amir.rouhi at rmit.edu.au
Thu May 24 03:28:29 CEST 2012

I use the below command for making video out of 5 different bmp images:

ffmpeg -f image2 -r 0.1 -i C:\test%1d.bmp -an -vcodec libx264 -threads 0
 -f h264 -r 0.5 -force_key_frames 0.1 -s 360x240 C:\5frameTest.264

I used  -force_key_frames  instead if -g to inforce the ffmpeg to generate
i-frames. BTW with -g i did not get even the correct video.
The generated video shows the images but not in same interval distance but
shows all 5 images in the video.

then i use JM decoder and tried to get the frames with s-type=2 nad the
result was just 3 , not 5.
Question is why 5 i-frame in ffmpeg can not be detected in JM?

On 22 May 2012 20:02, Alex Cohn <alexcohn at netvision.net.il> wrote:

> On Tue, May 22, 2012 at 11:47 AM,  <amir.rouhi at rmit.edu.au> wrote:
> >
> > I have noticed that the I-Frames in a pure h264 video created by ffmpeg
> is
> > not same as what JM detect as I-Frame in the same video.
> > In JM software s_type=2 means I_Frame. the number of s_types frames are
> > always lower than what ffmpeg shows.
> >  What is your advice?
> > Amir
> Would you like to upload an example?
> Alex
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Amir H. Rouhi
PhD Student/ CSIT RMIT University
Room: 14-09-04
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