High level syntax for video with mixed NAL unit types

A device for coding video data, the device comprising:

• a memory configured to store video data;
• and
• one or more processors implemented in circuitry and configured to:
• maintain a first reference picture list;
• maintain a second reference picture list;
• determine that a picture is an instantaneous decoding refresh (IDR) picture;
• process a syntax element indicating that that reference picture list syntax elements are present in a slice header for IDR video coding layer (VCL) network abstraction layer (NAL) units;
• and
• in response to determining that the picture is the IDR picture and that the syntax element indicates that the reference picture list syntax elements are present in the slice header for the IDR VCL NAL units, update the first reference picture list and the second reference picture list such that no picture in the first reference picture list and no picture in the second reference picture list precedes, in output order or decoding order, any preceding instant random access point (IRAP) picture in decoding order.

A non-transitory computer-readable storage medium storing instructions that when executed by one or more processors cause the one or more processors to:

• maintain a first reference picture list;
• maintain a second reference picture list;
• determine that a picture is an instantaneous decoding refresh (IDR) picture;
• process a syntax element indicating that that reference picture list syntax elements are present in a slice header for IDR video coding layer (VCL) network abstraction layer (NAL) units;
• and
• in response to determining that the picture is the IDR picture and that the syntax element indicates that the reference picture list syntax elements are present in the slice header for the IDR VCL NAL units, update the first reference picture list and the second reference picture list such that no picture in the first reference picture list and no picture in the second reference picture list precedes, in output order or decoding order, any preceding instant random access point (IRAP) picture in decoding order.

An apparatus for coding video data, the apparatus comprising:

• means for maintaining a first reference picture list;
• means for maintaining a second reference picture list;
• means for determining that a picture is an instantaneous decoding refresh (IDR) picture;
• means for processing a syntax element indicating that that reference picture list syntax elements are present in a slice header for IDR video coding layer (VCL) network abstraction layer (NAL) units;
• and
• means for updating, in response to determining that the picture is the IDR picture and that the syntax element indicates that the reference picture list syntax elements are present in the slice header for the IDR VCL NAL units, the first reference picture list and the second reference picture list such that no picture in the first reference picture list and no picture in the second reference picture list precedes, in output order or decoding order, any preceding instant random access point (IRAP) picture in decoding order.