[Mp4-tech] GOP concept in H.264

[tummala kalyani]

Hi All,
I would like to know about GOP concept in H.264. In JM encoder config file
there is a parameter "support for open GOP". How can I use this? I tried to
1-enable and 0-disable options. But I don't find any difference.
 There is provision to set I frame distance and number of B frames. When I
treid to set number of B frames more than 0 , it gives me an error message
saying that "Number of B frames should me more than frames skipped in the
input". What is the use of Frames skipped parameter in the encoder.cfg file
in JM?
 I need bitrate vs psnr comparison graphs for H.264 codec and MPEG-2 codec.
For that I am running JM and MPEG-2 reference softwares with foreman.yuv as
input video. I found that for baseline and main profiles H.264 codec output
file size is double to MPEG-2 file size. I use this filesize to calculate
bitrate( filesize * (frame rate / total frames)). But according to specs.
H.264 codec bitrate should be half to that of MPEG-2. But I am getting in
reverse. I am confused by this. I think I have not understood it properly.
Can some one explain me this clearly?
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