Question: how is <index> controlled?

[ReinhardKeil]

The SDS data stream is recorded to files with the following naming convention:

<name>.<index>.sds

<name> is a parameter in sdsRecOpen or sdsPlayOpen.

But how is <index> controlled? Is each sdsRecClose or sdsPlayClose incrementing it?

See https://github.com/ARM-software/SDS-Framework/blob/main/documentation/utilities.md

[DavidLesnjak]

For recording, the indexing mechanism works as follows:

• sdsRecOpen internally calls sdsioOpen (for write) to handle file creation.
• sdsioOpen creates a new file with the format: <name>.<index>.sds.
• The name parameter is passed from sdsRecOpen to sdsioOpen.
• The index starts at 0 and is automatically incremented for each new sdsioOpen call with the same name parameter.
• Before creating a new file, sdsioOpen checks if a file with the requested <name>.<index>.sds already exists:
  -- If the file exists, the index is incremented
  -- This process continues until the first available (unused) index is found.

For playback:

• sdsPlayOpen internally calls sdsioOpen (for read) to open sds file to be played.
• sdsioOpen checks for a file <name>.index.txt, where <name> is parameter in sdsPlayOpen passed to sdsioOpen
• if <name>.index.txt does not exist it creates one
• ⁠<name>.index.txt holds the index of <name>.<index>.sds file to be opened for playback
• if index in index file is missing or is invalid actual used index is 0
• sdsioOpen checks if a file with the <name>.<index>.sds exists.
  -- If exists: file <name>.<index>.sds is opend for playback and index is incremented and stored to <name>.index.txt (index is prepared for next sdsio)
  -- If not: sds file is not opened for playback and index is set 0 and stored to <name>.index.txt

[ReinhardKeil]

Covered on SDSIO_CMD_OPEN in
https://arm-software.github.io/SDS-Framework/main/theory/#sdsio-server-protocol