In continuation of #1554

When there are more than 2 layers, xWriteOutput() may access deleted SPS as well. So, it should use m_chromaFormatIDC saved in Picture object

In addition to it.

1) xWriteOutput() accesses potentially deleted SPS here:

  const SPS* activeSPS = (pcListPic->front()->cs->sps);
  uint32_t maxNrSublayers = activeSPS->getMaxTLayers();

This is safe in case of single-layer OLS only.

2) DecApp::decode() uses this pattern in multiple places:

  pcListPic->front()->cs->sps->getBitDepths();

In case of Multi-layer OLS, this SPS can be deleted. I suggest to save BitDepths in Picture object as well.

MR is coming.

In Multilayer bitstream SPS may contain no PTL information. In this case decoder issues warnings like:

• "Warning: Profile set to none or unknown value"
• "Warning: Level set to none, invalid or unknown value"

For Multilayer OLS PLT should be extracted from VPS.

Also, when vps_pt_present_flag[i] = 0 decoder should follow Spec:

When vps_pt_present_flag[ i ] is equal to 0, the profile, tier, and general constraints information for the i-th profile_tier_level( ) syntax structure in the VPS are inferred to be the same as that for the ( i − 1 )-th profile_tier_level( ) syntax structure in the VPS.

MR is coming

It is found since VTM16.1, VTM cannot correcly parsing the bitstream with userdata SEI, this problem comes from commit: b287c0be8d94a94500724eaeafc7a238c91c22e3, where the root cause is the payload of userdata SEI also go into function parseAndExtractSEIScalableNesting(), then VTM throw parsing error after then.