[x264-devel] Re: the difference between IDR and I frames

[Tuukka Toivonen]

On Mon, 13 Feb 2006 shauli.rozen at gmail.com wrote:

>I realize that IDR frames are very important to synchronizing .
>but , is there any thing different in the way they are coded against regular
>I frame.
>in a regular I frame , all the blocks are still coded as Intra right?

Yes, but

P frame after an I frame might have motion vectors pointing to frames
before the I frame, so you can't seek to I frame and continue
decoding happily as you don't then have the frames before the I frame.

IDR frame "breaks" the stream, ensuring that later frames don't
point to frames before the IDR frame. So, you need IDR frames
to seek to.

That's how I understand things...

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