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Rename initial_presentation_delay to avoid further confusion #104

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ocrete opened this issue Sep 11, 2018 · 1 comment
Open

Rename initial_presentation_delay to avoid further confusion #104

ocrete opened this issue Sep 11, 2018 · 1 comment
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editorial if approved, it does not affect the technical aspects of the specification (e.g. typo change)

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@ocrete
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ocrete commented Sep 11, 2018

Presentation & display sound like exactly the same thing to me and it seems it's creating a lot of confusion. Can we please rename it to something a bit more self-explanatory.

Based on Cyril's explanation in issue #101, it seem that it is actually the initial_display_delay but in samples instead of in frames, so I'd suggest initial_display_delay_in_samples_minus_1 as a slightly clearer name.

Also, I'd suggest adding this quote form Cyril to the spec:

The initial_presentation_delay concept is introduced to cope with problems happening in real implementation. When your decoder operates at the decoding speed limit of a level, if you don't wait to fill some reference buffers before starting to display, you may experience smoothness issues. The delay tells you how long your player should wait. If no information is provided, an AV1 decoder should wait for 10 frames to be decoded, but for some bitstreams you may need less than that. The delay at the elementary stream level is expressed in number of decoded frames. At the ISOBMFF level, it is express in number of decoded samples, because a player may not have access to the internals of a decoder to know how many frames were decoded when a TU is passed.
tomfinegan added a commit that referenced this issue Oct 10, 2018
@tomfinegan
Rename initial presentation delay fields.
a126a8c 
This editorial change renames the initial presentation
delay fields to avoid confusion between the ISOBMFF value,
which is in samples, and the AV1 bitstream value, which is
in frames.

- Rename initial_presentation_delay_present to
  initial_delay_present.
- Rename initial_presentation_delay_minus_one to
  initial_delay_samples_minus_one.

Closes #104
@tomfinegan tomfinegan mentioned this issue Oct 10, 2018
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tomfinegan added a commit that referenced this issue Oct 12, 2018
@tomfinegan
Rename initial presentation delay fields.
d9786f1 
This editorial change renames the initial presentation
delay fields to avoid confusion between the ISOBMFF value,
which is in samples, and the AV1 bitstream value, which is
in frames.

- Rename initial_presentation_delay_present to
  initial_delay_present.
- Rename initial_presentation_delay_minus_one to
  initial_delay_samples_minus_one.

Closes #104
@cconcolato cconcolato added the editorial if approved, it does not affect the technical aspects of the specification (e.g. typo change) label Jan 23, 2023
@cconcolato
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The example in the specification could be improved to use a real-world example and mark which frames are show_existing_frames vs not.

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Rename initial presentation delay fields. AOMediaCodec/av1-isobmff
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@ocrete @cconcolato