[Libav-user] ffmpeg and JM I_Frame nonconformity

[Alex Cohn]

On Thu, May 24, 2012 at 4:28 AM,  <amir.rouhi at rmit.edu.au> wrote:
> 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

-force_key_frames expects a comma separated list of timestamps, not a
"step" or something

BR,
Alex

> 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
> --
> Amir H. Rouhi
> PhD Student/ CSIT RMIT University
> Room: 14-09-04
> http://raws.adc.rmit.edu.au/~s3288736/blog2/