ESP32 xQueue, how to copy struct (memory) efficiently ?

[Deva_Rishi]

@kenb4

It's worth noting that many of the code examples, like for xQueueCreate, say

 // Create a queue capable of containing 10 pointers to AMessage structures.
 // These should be passed by pointer as they contain a lot of data.

So don't pass big structures. In the example, the (not-packed) struct is 24 bytes; that's "a lot". That means 512 for a sector (plus 2) is ginormous.

Yes it is, but it anyway needs to be buffered, why not let this API do that ?

@kenb4

If the SD writer is the last thing, it can free the block. If it needs to stick around and needs to be managed by the main task (or another cleanup task), then maybe there is a bool or bit in the struct to indicate that the write is done.

I was actually planning to just close the file if the Queue is empty and open it again. Apparently there is time to do so if the Queue is empty.
Leaving the file open is faster in theory, but in practice with these huge amounts of data, the differences are marginal, and anyway if there is time, it is a good idea to consolidate the file.

@Deva_Rishi

It didn't actually cause to much issue until i started playback. Reading from the SD-card is also not that fast.

Thinking about that i think i can even use the same Queue to read and buffer. When reading happens there is less processing happening overall, there is no reception processing, but i actually suspect that reading is even slower than writing to an SD. Another experiment to think about.

It's already really close to having the complete solution for what i am trying to do. There is still a memory saving that i think i can do in the outgoing I2S stream (3-step instead of 4-step) but the processing for it is to slow as yet and will need to be re-written optimized for speed (3-step should be nearly as fast as 4-step but as it is now it is about 4x slower)