IDR versus CDR for single-stream DASH

[benwaggoner]

I've been playing around with DASH packaging of HEVC, as DASH seems to what most folks are talking about doing for adaptive streaming of HEVC.

I've been encoding with x265 and packaging with mp4box.

For DASH content that need to do seamless bitrate switching, I'd obviously have to set --refresh IDR (aka Closed GOP).

But if I am making a single-stream DASH package, can I just leave it at the default of CDR (aka Open GOP)? Or do I need to use IDR there as well? I'm getting only a single mdat packaging from a test stream, and I'm wondering if using CDR might be why.

[pieter3d]

Do you mean a CRA picture? CRAs may be followed by leading pictures that may or may not be decodable. IDR pictures may not be followed by undecodable leading pictures (RADL vs RASL). Also an IDR starts a new Coded Video Sequence (CVS), CRA does not necessarily.

[benwaggoner]

Do you mean a CRA picture? CRAs may be followed by leading pictures that may or may not be decodable. IDR pictures may not be followed by undecodable leading pictures (RADL vs RASL). Also an IDR starts a new Coded Video Sequence (CVS), CRA does not necessarily.
x265 called it CDR, but it's probably the same thing.

It definitely seems to be better to use IDR for adaptive streaming.

[pieter3d]

If you have the clips, one of each, I can tell you how it is being done.