[x264-devel] A question about I-Frames and IDR-Frames

[Michael Fink]

Hi guys,

maybe you can help me. I'm just writing a thesis about video encoding 
and I've a question about h264.

On this mailing list and on doom9 I've found several threads in which 
the people are talking about I frames *and* IDR frames in h264. But I 
can't understand what they mean by an I frame in the context of h264?

The specification (ITU-T Rec. H.264 11/2007) is only talking of I/P/B 
slices. And it says an IDR frame is a frame which only consists of I or 
SI slices. That's clear. But I can't image what an I frame should be? A 
frame which is only intra-coded like in MPEG2? So in h264 that has to be 
a frame which only has I slices, right? But that's exactly the 
definition of an IDR frame?!?

*confused*