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MixPresentationOBU syntax/semantics simplification #760

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cconcolato opened this issue Sep 29, 2023 · 3 comments
Closed

MixPresentationOBU syntax/semantics simplification #760

cconcolato opened this issue Sep 29, 2023 · 3 comments
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editorial Improvements or additions to documentation

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@cconcolato
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cconcolato commented Sep 29, 2023

In the context of #759, I found it hard to navigate the spec around Mix Presentation OBU parameter definitions (element and output gains). IMHO, it could be simplified without changing the semantics or bitstreams, as follows:

The Mix Presentation OBU uses:

ElementMixConfig element_mix_config;

but ElementMixConfig is simply

class ElementMixConfig() {
  MixGainParamDefinition mix_gain;
}

My suggestion would be to remove the use of ElementMixConfig and simply use the following in the MixPresentationOBU

 MixGainParamDefinition element_mix_gain;

It means also moving the semantics of mix_gain from section 3.7.4 to section 3.7, merging it with the semantics of element_mix_config

Same for output_mix_config. The syntax in MixPresentationOBU should simply have:

MixGainParamDefinition output_mix_gain;

instead of

OutputMixConfig output_mix_config;

Section 3.7.5 can then be removed and merged with the semantics of output_mix_config (which would become output_mix_gain).

@cconcolato
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Similarly, the annotation syntax description could be simplified, instead of defining a class with a single field:

class MixPresentationElementAnnotations() {
  string audio_element_friendly_label;
}

or

class MixPresentationAnnotations() {
  string mix_presentation_friendly_label;
}

The MixPresentationOBU could simply contain:

  for (i = 0; i < count_label; i++) {
    string presentation_annotations;
  }

and

      for (i = 0; i < count_label; i++) {
        string element_annotations;
      }

In this case, I think also the use of arrays would simplify further the syntax.

string language_labels[count_label];
string localized_presentation_annotations[count_label];
...
string localized_element_annotations[count_label];

@tdaede tdaede added the editorial Improvements or additions to documentation label Oct 10, 2023
@tdaede
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tdaede commented Oct 10, 2023

We should look if we expect these to be updated right away in the version 2. If so we can leave them as is, if not we can simplify them.

@sunghee-hwang
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@felicialim, I am going to address this issue in the v1.1 spec. Please let me know if you have a concern.

@sunghee-hwang sunghee-hwang self-assigned this Jul 5, 2024
sunghee-hwang added a commit that referenced this issue Jul 14, 2024
Fix #760, Mix Presentation OBU Simplication
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