openCom-Companion/docs/utilities/rns_audio_call_calc.py

130 lines
5.0 KiB
Python

import os
import math
import RNS
import RNS.vendor.umsgpack as mp
def simulate(link_speed=9600, audio_slot_ms=70, codec_rate=1200, method="msgpack"):
# Simulated on-air link speed
LINK_SPEED = link_speed
# Packing method, can be "msgpack" or "protobuf"
PACKING_METHOD = method
# The target audio slot time
TARGET_MS = audio_slot_ms
# Packets needed per second for half-duplex audio
PACKETS_PER_SECOND = 1000/TARGET_MS
# Effective audio encoder bitrate
CODEC_RATE = codec_rate
# 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(CODEC_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+ENCRYPTED_PAYLOAD_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 = PACKET_LEN*PER_BYTE_LATENCY_MS
AIRTIME_PCT = (PACKET_AIRTIME/TARGET_MS) * 100
# Maximum amount of concurrent full-duplex
# calls that can coexist on the same channel
CONCURRENT_CALLS = math.floor(100/AIRTIME_PCT)
# Calculate latencies
TRANSPORT_LATENCY = round((PHY_OVERHEAD+RNS_OVERHEAD)*PER_BYTE_LATENCY_MS, 1)
PAYLOAD_LATENCY = round(ENCRYPTED_PAYLOAD_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 ENCRYPTED_PAYLOAD_LEN-PL_LEN == 1:
E_OPT_STR = "(optimal)"
else:
E_OPT_STR = "(sub-optimal)"
TOTAL_LATENCY = round(TARGET_MS+PACKET_LATENCY, 1)
print( "\n===== Simulation Parameters ===\n")
print(f" Packing method : {method}")
print(f" Sampling delay : {TARGET_MS}ms")
print(f" Codec bitrate : {CODEC_RATE} bps")
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 ===\n")
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 : {round(AIRTIME_PCT, 2)}% of link capacity")
print(f" Concurrent calls : {int(CONCURRENT_CALLS)}\n")
print(f" Full-duplex airtime : {round(AIRTIME_PCT*2, 2)}% of link capacity")
print(f" Concurrent calls : {int(CONCURRENT_CALLS/2)}")
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(method="msgpack")
#print("\n\n= With protobuf ===============")
#simulate(method="protobuf")