Added ping request to keep connection open

[chegewara]

Changes maybe are not optimized, because im learning your code. It works for about 50 minutes, then esp32 crashes.

With this code also changes from https://github.com/kodera2t/Simple_Alexa_dif are added.

[chegewara]

I know why its crashing after 50-ish minutes. Amazon server is sending GOAWAY frame. Waiting for answer now:
https://forums.developer.amazon.com/questions/10684/is-there-any-limit-of-avs-api.html?childToView=172203#answer-172203

[MrBuddyCasino]

Thanks for this PR. Whats the reason for that one? I'd understand 1.0, whats with 0.52?
renderer_config->sample_rate_modifier = 0.52;

[chegewara]

On my board it works with that value with right alexa speed and pitch. Im think it should be 0.544 in fact (i dont have logs right now to show how i counted that). From this comment im guessing its hardware dependent:
#13 (comment)

[MrBuddyCasino]

If ping was async to save on stack RAM that would be better, but this is a good start. Merged.

[chegewara]

Yes, im aware of that, but im not good enough programmer to implement this. Also there is another option, but i dont know how to implement it. nhttp2 can send PING frame. I think it would be even better solution if someone can implement it.

[chegewara]

@MrBuddyCasino I did changes because i saw those two lines:

I (3413442) renderer: changing sample rate from 24000 to 44100
I (3413445) I2S: PLL_D2: Req RATE: 23990, real rate: 24038.000, BITS: 16, CLKM: 26, BCK: 8, MCLK: 6142771.446, SCLK: 769216.000000, diva: 64, divb: 3

Also i had to change this value to 22050 and now online mp3 files are played by webradio with right pitch/speed:
https://github.com/MrBuddyCasino/ESP32_Alexa/blob/master/main/app_main.c#L97