[Mp4-tech] [H.264] Use of SPS/PPS in H.264

[Steinberg Erez-RM96322]

Hi,
H.264 allows up to 32 sequence parameter sets (SPS) and 256 picture
parameter sets (PPS) in a stream.
An SPS includes information on the picture resolution, number of
reference frame, profile and level. These are cardinal for decoder
initialization and setup.
My questions:
(1) Is a decoder expected to handle spontaneous changes in these
parameters? I.e., if an IDR picture is received with a different
PPS/SPS, is it supposed to reallocate all its memory buffers? (This is
effectively resetting the decoder)
(2) For practical implementations -- are there any known applications
that use different SPSs in the same stream? Or, can a decoder assume
only one SPS?
Thanks for your help!
Regards,
Erez