[FFmpeg-user] pict_type="I"

[Oliver Fromme]

Mark Filipak wrote:
 > Since 00305.m2ts is AVC encoded, there are I slices in it but not I frames -- I P & B frames are 
 > MPEG-1 & MPEG-2.

That's not completely correct.  I suggest you read a bit about
basic concepts and terminology of H.264 (AVC).  I'll try to
summarize it:

H.264 (AVC) has I-frames, too.  These frames may use only spatial
prediction, i.e. they contain only intra-predicted macroblocks.
P-frames and B-frames may use both spatial and temporal prediction,
i.e. they contain inter-predicted and intra-predicted macroblocks
(where P-frames are restricted to forward prediction, and B-frames
may use both forward and backward prediction).

Note that a slice is basically just a group of macroblocks that
describe a certain region of a frame and share some common
properties.  For example, an "I-slice" is a group of macroblocks
that use only spatial prediction.  And an I-frame contains only
intra-predicted slices (I-slices), while a P-frame may contain
P-slices and I-slices, and a B-frame may contain all three types
of slices.

Finally, there are IDR-frames.  These are I-frames that signify
a closed GOP.  That is, temporal predictions may not cross the
boundary of an IDR-frame.  I-frames that are part of an open GOP
are not IDR-frames.

Best regards
 -- Oliver