JVET-AM0182 AHG9: On the Danmu SEI message [S. Zhao, Y. He, L. Kerofsky, M. Karczewicz (Qualcomm)]
This proposal introduces the following changes to the Danmu SEI message in the current VSEI Tuc:
- Propose a syntax element to specify Danmu background colour
- Propose a syntax element to specify Danmu display type
- Propose a syntax element to specify Danmu font type
- Propose a syntax element to specify Danmu transparency level
- Propose a syntax element to specify Danmu font size.
- Correct the inference of di_end_delta_poc syntax when it is not present
Item 2 includes display type idc values 5 and 6 that are similar to table entries proposed in JVET-AM0154.
It was suggested that the proposed display type idc value 7 is underspecified as it doesn’t indicate what direction the danmu will move.
For item 2, see notes for JVET-AM0154.
It was questioned if font size would vary for individual messages.
In the proposal, the new syntax elements are signalled for each message, which may be wasteful.
It was suggested that there should be an unspecified font type.
The font_type_idc[ i ] syntax element can be used to indicate open file format, but does not provide any syntax to indicate the actual font used (e.g. Times New Roman, Arial, etc.)
Further study on font type is encouraged.
For the signalling of background colour, there is no option for transparent background.
In some systems, the viewer can select the transparency value, rather than having the transparency being associated with individual danmu messages.
It was questioned if the transparency is performed in the linear or non-linear domain.
What is the interaction between background colour and transparency? Does it apply to the background or to the font or to the composited font + background?
Further study encouraged on items 1, 3, 4, and 5.
JVET-AM0182 AHG9: On the Danmu SEI message
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