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CCSMB-5: PCM Audio Transmissions over modem #18

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CCSMB-5: PCM Audio Transmissions over modem #18

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a170d9f
First iteration
EmmaKnijn Jan 7, 2023
01afc24
Change songName to be more generic
EmmaKnijn Jan 7, 2023
08e8161
Drop the id field
EmmaKnijn Jan 7, 2023
b8fab17
Add protocol field and clarify the types in the fields
EmmaKnijn Jan 7, 2023
a7a79e5
Enforce protocol to be CCSMB-5
EmmaKnijn Jan 7, 2023
3445da9
Fix markdown formatting
EmmaKnijn Jan 7, 2023
8ca7b64
Restructure compliancy and expand on crosstalk
EmmaKnijn Jan 7, 2023
bccaf85
Improve based on some reviews
EmmaKnijn Jan 8, 2023
aa863e1
Add port allocation
EmmaKnijn Jan 8, 2023
c5a8320
Add a base for the discovery packet
EmmaKnijn Feb 28, 2023
2f87bec
Add a couple things that people requested
EmmaKnijn Mar 13, 2023
1b026dd
Add reference to RFC 2119
EmmaKnijn Oct 26, 2023
eb04510
Add clarification for the packet timing
EmmaKnijn Oct 26, 2023
5122823
Change title
EmmaKnijn Oct 26, 2023
70dba1f
Change the protocol name to PASC
EmmaKnijn Oct 26, 2023
779b4e9
Grammatical changes
EmmaKnijn Oct 26, 2023
2d2b02f
Grammatical fix
EmmaKnijn Oct 26, 2023
f6179e0
Recommendation on packet length
EmmaKnijn Oct 26, 2023
05e4960
Add multiple channels, clean up some stuff, add example packet
EmmaKnijn Mar 29, 2024
953963f
Enforce 759 for replyChannel
EmmaKnijn Mar 29, 2024
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51 changes: 51 additions & 0 deletions Standards/CCSMB-5.md
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# CCSMB-5: PCM Audio Transmissions over modem
*Author: Emma Beurskens <@emmaknijn>*
*Version: v1.0.0*
*Last updated: YYYY-MM-DD*

## Design
A client will only listen to packets while the audio is being transmitted from a server

The server will communicate to the client over modem
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All servers must be on seperate channels

PASC refers to "Protocol for Audio Streaming in Computercraft"
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

## Packet
An audio packet consists of the following fields in a table:
- `buffer`: A table that contains Signed 8-bit PCM @ 48kHz audio
- `id`: The ID of the server sending the message
- `station`: A string that contains the name of the radio station
- `metadata`: A table that contains additional metadata
- `protocol`: A string that contains the protocol used

The metadata can contain the following fields:
- `song`: A string that contains the song name, if one is being played, not required
- `artist`: A string that contains the song artist, if a song is being played, not required
- `owner`: A string that contains the station owner's (ingame or discord) username, not required
- `alternative`: A table that contains alternative station channels, with integers inside, not required


In order to be compliant the
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This is worded a bit informally; I'd prefer it to use full sentences in bullet points or an ordered list.

We should also mention RFC 2119 if using keywords like "MUST", "SHOULD", etc.

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Could you write an example, I feel like writing the same In order to be compliant the in 5 bullet points is a bit redundant

- protocol field must be "PASC"
- client must be able to deal with crosstalk by allowing the user to select a station if there are multiple stations on a single channel
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- client must reject a packet with an invalid `protocol` field
- server must time the packets appropriately in a way that the client is just able to play back the buffer
- The server must wait exactly as long as the piece of audio being sent when timing the packets, if this doesn't happen the audio might skip or stutter on the client

## Discovery
A discovery packet is sent over channel 759 and must contain the following fields in a table:
- `type`: The type of request

The following fields are required only for servers responding to a discovery packet
- `channel`: An integer that contains the modem channel of the radio station
- `station`: A string that contains the name of the radio station
- `metadata`: The same metadata that is also sent with an audio packet
- `protocol`: A string that contains the protocol used

In order to be compliant the
- protocol field must be "PASC"
- client must set the `type` field to `discovery` if they intend to request servers