[Libav-user] Extracting I-Frame intra-prediction modes

[Rouhi Amirhossein2]

Unfortunately -debug does not serve my purpose . i need intra-predictions
and i should add some lins in ffmpeg coding like fprint () function to save
them in a text file.

On 26 June 2012 20:51, Alex Cohn <alexcohn at netvision.net.il> wrote:

> On Tue, Jun 26, 2012 at 12:21 PM, Rouhi Amirhossein2
> <amir.rouhi at rmit.edu.au> wrote:
> > Hi Misha
> > Thanks for prompt reply. That would be a very useful code for extracting
> key
> > frame images. but actually need to extract the intra-prediction modes in
> > each key frame of an input video stream. Can you help me to achieve this?
> > the input of the program would be an h264 raw video file and the output
> > would be a text file that stores intra-prediction modes with related MB
> > address and i-frame id.
> >
> >
> > On 26 June 2012 19:12, Misha Penkov <misha.penkov at gmail.com> wrote:
> >>
> >> On 26 June 2012 18:05, Rouhi Amirhossein2 <amir.rouhi at rmit.edu.au>
> wrote:
> >> >
> >> > Hi
> >> > You know that in h264, a methos is used for compression which is
> called
> >> > intra prediction method. totally we have 9 intra prediction modes
> which
> >> > showing different direction of top and left side pixels of 4x4
> blocks. I
> >> > want to extract such modes in any frame that uses intra prediction
> such
> >> > as
> >> > I-Frames and IDR,s. Do you know how can i achive this purpose?
> >> > In JM software i did the same in decoder, do you think it should be
> done
> >> > in
> >> > FFplay as a decoder or it can be done by FFmpeg?
> >>
> >> AFAIK, H.264 I-frames and keyframes are the same thing.  Once you have
> >> an AVFrame, you can check its key_frame member.  It will be non-zero
> >> if it's a keyframe (I-frame).
> >>
> >> For full code, have a look here:
> >>
> >> https://github.com/mpenkov/sandpit/blob/master/ffmpeg/keyframes.c
> >>
> >> Provided that you're using MP4 as the container, you can confirm that
> >> the keyframes extracted are indeed I-frames by using the mp4videoinfo
> >> utility (http://mpeg4ip.sourceforge.net/documentation/index.php).
> >>
> >> > Thanks for your expert advice.
> >> > Amir
> >> >
> > --
> > Amir H. Rouhi
> > PhD Student/ CSIT RMIT University
> > Room: 14-09-04
> > http://raws.adc.rmit.edu.au/~s3288736/blog2/
>
> Check ffmpeg -debug options, especially pict and mv:
>
> -debug             <flags> EDVAS print specific debug info
>   pict                    .DV.. picture info
>   mb_type                 .DV.. macroblock (MB) type
>   mv                      .DV.. motion vector
>
> Regards,
> Alex Cohn
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>



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