def test_get_out_of_order_packets():
# Create jitter buffer
buffer_length = 0
jitter_buffer = JitterBuffer(buffer_length=buffer_length)
# First valid put (sets expected value)
value0 = 0
jitter_buffer.put_packet(value0, value0)
assert len(jitter_buffer) == buffer_length + 1
# Out-of-order put
value1 = 2
jitter_buffer.put_packet(value1, value1)
assert len(jitter_buffer) == buffer_length + 2
# Get initial packet
out = jitter_buffer.get_packet()
assert out is value0
assert len(jitter_buffer) == buffer_length + 1
# Get missing packet
out = jitter_buffer.get_packet()
assert out is None
assert len(jitter_buffer
) == buffer_length + 1 # because the None wasn't ever stored
# Second get (from out-of-order packets)
out = jitter_buffer.get_packet()
assert out is value1
assert len(jitter_buffer) == buffer_length
def test_stress_test2():
import random
random.seed(1234)
from collections import deque
# Create jitter buffer
jitter_buffer = JitterBuffer()
# Set the roll-over value
roll_over = 1000
jitter_buffer._seq_no_rollover = roll_over
# Number of packets to simulate
number_of_packets = 200000
# Duration per packet at source
packet_duration = 20 / 1000 # seconds
# Packet values
packet_values = [i for i in range(number_of_packets)]
# Generate missing packets
prob_missing = 0.05
keep = int(len(packet_values) * (1 - prob_missing))
packet_values = random.sample(packet_values, keep)
# Packet arrival times (no delay)
packet_times = [i * packet_duration for i in packet_values]
# Add noise in packet arrival time
mu = 0
sigma = packet_duration * 5
packet_times = [t + random.gauss(mu, sigma) for t in packet_times]
# Join the values and times
packets = zip(packet_values, packet_times)
# Sort the packets into the correct order
sorted_packets = sorted(packets, key=lambda p: p[1])
sorted_packets = deque(sorted_packets)
t = 0 + packet_duration
while True:
# If the deque is empty, break
if len(sorted_packets) == 0:
break
# Put first packet into the buffer if it appears before time t
if sorted_packets[0][1] < t:
value = sorted_packets[0][0]
#print("putting", value)
jitter_buffer.put_packet(value % roll_over, value)
sorted_packets.popleft()
else:
# Get the next packet
out = jitter_buffer.get_packet()
#print("got", out)
# Increment simulated time
t += packet_duration
def test_repeated_alternating_put_get():
jitter_buffer = JitterBuffer(buffer_length=0)
for i in range(1000):
jitter_buffer.put_packet(i, i)
out = jitter_buffer.get_packet()
assert out == i
assert len(jitter_buffer) == 0
def test_get_from_empty():
buffer_length = 0
jitter_buffer = JitterBuffer(buffer_length=buffer_length)
# First valid put
value = 0
jitter_buffer.put_packet(0, value)
assert len(jitter_buffer) == buffer_length + 1
# Get after put
out = jitter_buffer.get_packet()
assert out == value
assert len(jitter_buffer) == buffer_length
# Second get (from empty buffer)
out = jitter_buffer.get_packet()
assert out is None
assert len(jitter_buffer) == 0
def test_repeated_alternating_put_get_with_buffer():
buffer_length = 3
jitter_buffer = JitterBuffer(buffer_length=buffer_length)
for i in range(1000):
jitter_buffer.put_packet(i, i)
out = jitter_buffer.get_packet()
if i < buffer_length:
assert out is None
else:
assert out == i - buffer_length
assert len(jitter_buffer) == buffer_length
def test_ignores_before_first_put():
buffer_length = 1
jitter_buffer = JitterBuffer(buffer_length=buffer_length)
# Get before put
out = jitter_buffer.get_packet()
assert out is None
assert len(jitter_buffer) == buffer_length
# First valid put
value = 0
jitter_buffer.put_packet(0, value)
assert len(jitter_buffer) == buffer_length + 1
# Get after put
out = jitter_buffer.get_packet()
assert out is None
assert len(jitter_buffer) == buffer_length
out = jitter_buffer.get_packet()
assert out == value
assert len(jitter_buffer) == buffer_length - 1
def test_out_of_order_packet():
jitter_buffer = JitterBuffer(buffer_length=0)
jitter_buffer.put_packet(0, 0)
assert len(jitter_buffer) == 1
out = jitter_buffer.get_packet()
assert out == 0
assert len(jitter_buffer) == 0
# Packet should be discarded
jitter_buffer.put_packet(0, 0)
assert len(jitter_buffer) == 0
# Packet should be kept
jitter_buffer.put_packet(2, 2)
assert len(jitter_buffer) == 1