[Mp4-tech] MAX GOP size

[Ilan Daniel]

Kajanida
To my knowledge, you need the 'I' Frames in order to start decoding in a middle of the stream (random access) like when you change channel in STB and expect to start viewing the new channel in a reasnible time (less than 1 sec).
That is why GOP sizes of 12 and 15 are very popular in MPEG2, cause they give "access time" 500mS in 25 and 30 frmaes per second.
Another option (in MPEG2 and maybe also H.264?) is not to send 'I' Frames but make sure that all the MB's are sent as 'I' MB after certain period (that is called also Intra refresh).
Regards,
Ilan Daniel
________________________________
From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of kjnd kjnd
Sent: ש 28 ינואר 2006 00:54
To: Mp4-tech lists.mpegif.org
Subject: [Mp4-tech] MAX GOP size
  Dear Experts, 
   Is there any limit on the MAX gop size in h.264 std.? if no then what are the considerations one should have if they require a GOP size of 1000 or 1500 ( GOP here can be an IDR period(frames between IDR) or the no. of frames between two 'I' Frames as well)) 
Regards,
kajanida
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