From 262d5521083b737754695e3856e68df463d55c48 Mon Sep 17 00:00:00 2001 From: Mark Qvist Date: Wed, 22 May 2024 15:54:06 +0200 Subject: [PATCH] Added calculator utility --- docs/utilities/rns_audio_call_calc.py | 122 ++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) create mode 100644 docs/utilities/rns_audio_call_calc.py diff --git a/docs/utilities/rns_audio_call_calc.py b/docs/utilities/rns_audio_call_calc.py new file mode 100644 index 0000000..4d1b9a5 --- /dev/null +++ b/docs/utilities/rns_audio_call_calc.py @@ -0,0 +1,122 @@ +import os +import math +import RNS +import RNS.vendor.umsgpack as mp + +def simulate(method="msgpack"): + # Simulated on-air link speed + LINK_SPEED = 9600 + + # Packing method, can be "msgpack" or "protobuf" + PACKING_METHOD = method + + # The target audio slot time + TARGET_MS = 70 + + # Packets needed per second for half-duplex audio + PACKET_PER_SECOND = 1000/TARGET_MS + + # Effective audio encoder bitrate + CODEC2_RATE = 1200 + + # Maximum number of supported audio modes + MAX_ENUM = 127 + + # Per-packet overhead on a established link is 19 + # bytes, 3 for header and context, 16 for link ID + RNS_OVERHEAD = 19 + + # Physical-layer overhead. For RNode, this is 1 + # byte per RNS packet. + PHY_OVERHEAD = 1 + + # Total transport overhead + TRANSPORT_OVERHEAD = PHY_OVERHEAD+RNS_OVERHEAD + + # Calculate parameters + AUDIO_LEN = int(math.ceil(CODEC2_RATE/(1000/TARGET_MS)/8)) + PER_BYTE_LATENCY_MS = 1000/(LINK_SPEED/8) + + # Pack the message with msgpack to get real- + # world packed message size + + if PACKING_METHOD == "msgpack": + # Calculate msgpack overhead + PL_LEN = len(mp.packb([MAX_ENUM, os.urandom(AUDIO_LEN)])) + PACKING_OVERHEAD = PL_LEN-AUDIO_LEN + elif PACKING_METHOD == "protobuf": + # For protobuf, assume the 8 bytes of stated overhead + PACKING_OVERHEAD = 8 + PL_LEN = AUDIO_LEN+PACKING_OVERHEAD + else: + print("Unsupported packing method") + exit(1) + + # Calculate required encrypted token blocks + BLOCKSIZE = 16 + REQUIRED_BLOCKS = math.ceil((PL_LEN+1)/BLOCKSIZE) + ENCRYPTED_PAYLOAD_LEN = REQUIRED_BLOCKS*BLOCKSIZE + BLOCK_HEADROOM = (REQUIRED_BLOCKS*BLOCKSIZE) - PL_LEN - 1 + + # The complete on-air packet length + PACKET_LEN = PHY_OVERHEAD+RNS_OVERHEAD+PL_LEN + PACKET_LATENCY = round(PACKET_LEN*PER_BYTE_LATENCY_MS, 1) + + # TODO: This should include any additional + # airtime consumption such as preamble and TX-tail. + PACKET_AIRTIME = round(PACKET_LEN*PER_BYTE_LATENCY_MS, 1) + AIRTIME_PCT = round( (PACKET_AIRTIME/TARGET_MS) * 100, 1) + + # Calculate latencies + TRANSPORT_LATENCY = round((PHY_OVERHEAD+RNS_OVERHEAD)*PER_BYTE_LATENCY_MS, 1) + + PAYLOAD_LATENCY = round(PL_LEN*PER_BYTE_LATENCY_MS, 1) + RAW_DATA_LATENCY = round(AUDIO_LEN*PER_BYTE_LATENCY_MS, 1) + PACKING_LATENCY = round(PACKING_OVERHEAD*PER_BYTE_LATENCY_MS, 1) + + DATA_LATENCY = round(ENCRYPTED_PAYLOAD_LEN*PER_BYTE_LATENCY_MS, 1) + ENCRYPTION_LATENCY = round((ENCRYPTED_PAYLOAD_LEN-PL_LEN)*PER_BYTE_LATENCY_MS, 1) + if ENCRYPTION_LATENCY == PER_BYTE_LATENCY_MS: + E_OPT_STR = "(optimal)" + else: + E_OPT_STR = "(sub-optimal)" + + TOTAL_LATENCY = round(TARGET_MS+PACKET_LATENCY, 1) + + print( "\n === Simulation Parameters ===") + print(f" Packing method : {method}") + print(f" Sampling delay : {TARGET_MS}ms") + print(f" Audio data : {AUDIO_LEN} bytes") + print(f" Packing overhead : {PACKING_OVERHEAD} bytes") + print(f" Payload length : {PL_LEN} bytes") + print(f" AES blocks needed : {REQUIRED_BLOCKS}") + print(f" Encrypted payload : {ENCRYPTED_PAYLOAD_LEN} bytes") + print(f" Transport overhead : {TRANSPORT_OVERHEAD} bytes ({RNS_OVERHEAD} from RNS, {PHY_OVERHEAD} from PHY)") + print(f" On-air length : {PACKET_LEN} bytes") + print(f" Packet airtime : {PACKET_AIRTIME}ms") + + print( "\n === Results for "+RNS.prettyspeed(LINK_SPEED)+" Link Speed ===") + print(f" Final latency : {TOTAL_LATENCY}ms") + print(f" Recording latency : contributes {TARGET_MS}ms") + print(f" Packet transport : contributes {PACKET_LATENCY}ms") + print(f" Payload : contributes {PAYLOAD_LATENCY}ms") + print(f" Audio data : contributes {RAW_DATA_LATENCY}ms") + print(f" Packing format : contributes {PACKING_LATENCY}ms") + print(f" Encryption : contributes {ENCRYPTION_LATENCY}ms {E_OPT_STR}") + print(f" RNS+PHY overhead : contributes {TRANSPORT_LATENCY}ms") + print(f"") + print(f" Half-duplex airtime : {AIRTIME_PCT}% of link capacity") + print(f" Full-duplex airtime : {AIRTIME_PCT*2}% of link capacity") + + if BLOCK_HEADROOM != 0: + print("") + print(f" !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!") + print(f" Unaligned AES block! Each packet could fit") + print(f" {BLOCK_HEADROOM} bytes of additional audio data") + print(f" !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!") + +print( "\n= With mspack =================") +simulate("msgpack") + +print("\n\n= With protobuf ===============") +simulate("protobuf")