Techniques for jitter buffer delay management
View Patent ↗Techniques are provided to allow a jitter buffer to automatically reach a quiescent number of packets in the jitter buffer, based on current network conditions. Generally, no explicit jitter buffer delay is assumed, and a current packet is repeat played if no new packets are available in the jitter buffer. If there are too many packets in the jitter buffer, a newly received packet is discarded. When a packet is replayed, the delay associated with a jitter buffer is effectively increased. This is not an explicit jitter buffer delay, but, instead, there is an implicit delay associated with the jitter buffer. When a packet is discarded, the delay associated with a jitter buffer is effectively decreased. Again, this is an implicit jitter buffer delay. By repeat playing packets and discarding packets when the jitter buffer is full, an appropriate level of packets may be determined and maintained in the jitter buffer.
1. A method for jitter buffer delay management, the method comprising the steps of:
receiving a received packet;
when there are no packets in a buffer, performing the following steps:
playing the received packet, the step of playing performed without waiting an explicit delay;
determining, after the received packet is played, if there are any new packets in the buffer;
replaying only a portion of the received packet when there are no new packets in the buffer, the step of replaying thereby increasing an implicit delay; and
when there is at least one packet in the buffer and a number of packets in the buffer is below a predetermined value, performing the following steps:
placing the received packet in the buffer;
determining if the received packet should be played before a current packet; and
discarding the received packet when the received packet should be played before a current packet.
2. The method of claim 1 , further comprising a step of discarding a received packet by never placing the received packet in the buffer.
3. The method of claim 1 , wherein the steps of determining if there are any new packets in the buffer and replaying can be performed multiple times, and wherein the step of when there are no packets in a buffer, performing the following steps, further comprises the steps of determining if the received packet has been played a predetermined number of times, and not replaying the received packet when the received packet has been played a number of times.
4. The method of claim 1 , wherein the step of determining if the received packet should be played before a current packet further comprises the steps of determining timestamps for each of the received packet and current packet and using the timestamps to determine if the received packet should be played before a current packet by determining which packet of the received and current packets was created first.
5. The method of claim 1 , wherein the step of determining if the received packet should be played before a current packet further comprises the steps of determining sequence numbers for each of the received packet and current packet and using the sequence numbers to determine if the received packet should be played before a current packet by determining which packet of the received and current packets was created first.
6. The method of claim 1 , wherein the step of when there is at least one packet in the buffer and a number of packets in the buffer is below a predetermined value. placing the received packet in the buffer further comprises the steps of:
determining if a current packet has been played less than a predetermined number of times;
determining sequences for the received packet and the current packet;
determining if the number of packets in the buffer is less than a second predetermined value;
replaying a current packet when the current packet has been played less than the predetermined number of times, the current packet should be played before the received packet according to the sequences, and the number of packets in the buffer is less than the second predetermined value; and
playing the received packet when the current packet should be played before the received packet according to the sequences and either the current packet has been played more than the predetermined number of times or the number of packets in the buffer is less than the second predetermined value.
7. A method for jitter buffer delay management, the method comprising the steps of:
determining a number of packets currently in a buffer;
selecting, based on the settings for a buffer limit value, a replay value, a repeat play value, and the number of packets currently in the buffer, one of the steps of (i) playing a packet from the buffer, (ii) replaying a previously played packet from the buffer, (iii) discarding a packet from the buffer, (iv) selecting another packet from the buffer, and (v) waiting for another packet to be put in the buffer; wherein the replay value indicates a maximum number of times a particular packet is allowed to be replayed and wherein the repeat play value indicates a maximum number of packets currently in said buffer above which replaying of packets is disallowed; and
performing the selected step of steps (i) through (v).
8. The method of claim 7 , further comprising the steps of:
setting the buffer limit value the buffer limit value indicating a maximum number of packets allowed in a buffer;
setting the replay value, the replay value indicating a maximum number of times a particular packet is allowed to be replayed; and
setting the repeat play value, the repeat play value indicating a packet level above which replaying of packets is disallowed.
9. The method of claim 8 , further comprising the steps of:
receiving a received packet;
determining whether the received packet should be placed into the buffer; and
discarding the received packet when it is determined that the received packet should not be placed into the buffer.
10. The method of claim 9 , wherein:
the step of determining whether the received packet should be placed into the buffer comprises the step of determining whether the number of packets in the buffer is equal to the buffer limit value; and
the step of discarding the received packet when it is determined that the received packet should not be placed into a buffer comprises the step of discarding the received packet when it is determined that the number of packets in the buffer is equal to the buffer limit value.
11. The method of claim 8 , wherein:
step (i) is selected when there is at least one packet in the buffer, one of the at least one packets has not been previously played, and the one packet is next in a sequence;
step (ii) is selected either when the buffer is empty and a number of times a current packet has been played is less than the replay value or a number of packets in the buffer is less than the repeat play value and a next packet in the sequence is not in the buffer;
step (iii) is selected when the number of packets in the buffer is equal to the buffer limit value or when a received packet occurs earlier in the sequence than a current packet;
step (iv) is selected when there is at least one packet in the buffer and when a received packet occurs earlier in the sequence than a current packet; and
step (v) is selected when the buffer is empty and a previously played packet has been played a number of times equal to the replay value.