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add c608 mapping #823

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2fecb92
add c608 mapping
dericed Apr 10, 2024
8eeee1b
add S_C608 subtitle track
dericed Apr 21, 2024
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26 changes: 26 additions & 0 deletions block_additional_mappings/c608-captions.md
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## c608 Captions

### c608 Captions Description

CEA-608 captions can be stored in `BlockMore Element` to associate the content of a Matroska Block (typically a video frame) with closed captioning data. Storing CEA-608 caption data requires that the corresponding Block SHALL NOT use Lacing.
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@robUx4 robUx4 Jan 26, 2025

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SHALL NOT should have "**" around it.


The `BlockAdditional Element` stores the c608 data as a array of one or more octet pairs from one data channel of a CEA-608 data stream with each octet pair corresponding to a video frame. For more information about the content see [@!ANSI-CTA-608-E-S-2019].

### BlockAddIDType

The BlockAddIDType value reserved for CEA-608 captions is "608".

### BlockAddIDName

The BlockAddIDName value reserved for CEA-608 captions is "CEA-608 captions".

### BlockAddIDExtraData

BlockAddIDExtraData MAY contain a value as defined by Section 6.4.3.3 of [!@DASH-IF-IOP] that describes the caption services and language. An ABNF from [!@DASH-IF-IOP] for this value is restated here for convenience:
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@robUx4 robUx4 Oct 22, 2024

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MAY should be normative

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BlockAddIDExtraData MAY contain a value as defined by Section 6.4.3.3 of [!@DASH-IF-IOP] that describes the caption services and language. An ABNF from [!@DASH-IF-IOP] for this value is restated here for convenience:
BlockAddIDExtraData **MAY** contain a value as defined by Section 6.4.3.3 of [!@DASH-IF-IOP] that describes the caption services and language. An ABNF from [!@DASH-IF-IOP] for this value is restated here for convenience:


```
@value = (channel *3 [";" channel]) / (language *3[";" language])
2 channel = channel-number "=" language
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@robUx4 robUx4 Apr 13, 2024

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Are the numbers at the beginning of each line expected in the ABNF description ?

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@robUx4 robUx4 Oct 22, 2024

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To answer myself: yes, these number are line numbers in the PDF. They should be removed here.

3 channel-number = CC1 | CC2 | CC3 | CC4
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CC1/CC2/CC3/CC4 are missing a definition

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@robUx4 robUx4 Oct 22, 2024

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Given the examples in the PDF they are litteral strings.

In a more recent version of the split PDF it says:

SCTE 214-1 [5], section 7.2.3, “Signalling CEA-608 caption service metadata”

In the current version of SCTE 214-1 that's section 8.2.3 and the BNF has been fixed:

@value = language / channel 0*3 [";" channel]
channel = channel-number "=" language
channel-number = “CC1” / “CC2” / “CC3” / “CC4”
language = 3ALPHA ; language code per ISO 639-3

We should probably use that and also reference that source directly.

4 language = 3ALPHA ; language code per ISO 639.2/B
```
20 changes: 20 additions & 0 deletions rfc_backmatter_codec.md
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<date year="2022" month="October" day="6"/>
</front>
</reference>

<reference anchor="ANSI-CTA-608-E-S-2019" target="https://shop.cta.tech/products/line-21-data-services">
<front>
<title>Line 21 Data Services ANSI/CTA-608-E S-2019</title>
<author>
<organization>ANSI/CTA</organization>
</author>
<date year="2019" month="December"/>
</front>
</reference>

<reference anchor="DASH-IF-IOP" target="https://dashif.org/docs/DASH-IF-IOP-v4.3.pdf">
<front>
<title>Guidelines for Implementation: DASH-IF Interoperability Points</title>
<author>
<organization>DASH Industry Forum</organization>
</author>
<date year="2018" month="November" day="18"/>
</front>
</reference>