Jitter estimation for MPEG receivers
View Patent ↗A method is disclosed for estimating jitter in an MPEG receiver. An MPEG transport stream is received, including a plurality of packets. At least one of the plurality of packets includes a program clock reference (PCR) value. For each PCR value received, a current packet delay is calculated by subtracting a system time clock (STC) value of the MPEG receiver from the PCR value. If the current packet delay is greater than an upper boundary value or less than a lower boundary value, one or more of an upper and a lower boundary impact density is updated, and based on a comparison of the upper boundary impact density to the lower boundary impact density, one or more of the upper boundary value and the lower boundary value is updated. A current jitter value is calculated using the difference between the upper and the lower boundary value.
1. A method for estimating jitter in an MPEG receiver, the method comprising:
receiving an MPEG transport stream comprising a plurality of packets, wherein at least one of the plurality of packets comprises a program clock reference (PCR) value; and
for each PCR value received:
calculating a current packet delay by subtracting a system time clock (STC) value of the MPEG receiver from the PCR value;
if the current packet delay is greater than an upper boundary value, updating an upper boundary impact density or if the current packet delay is less than a lower boundary value, updating a lower boundary impact density
comparing the upper boundary impact density and the lower boundary impact density;
if the upper boundary impact density is greater than the lower boundary impact density, and if the current packet delay is greater than the upper boundary value, incrementing the upper boundary value and the lower boundary value by a window shift value;
if the upper boundary impact density is greater than the lower boundary impact density, and if the current packet delay is less than the lower boundary value, setting the lower boundary value to the current packet delay;
if the lower boundary impact density is greater than the upper boundary impact density, and if the current packet delay is greater than the upper boundary value, setting the upper boundary value to the current packet delay;
if the lower boundary impact density is greater than the upper boundary impact density, and if the current packet delay is less than the lower boundary value, decrementing the upper boundary value and the lower boundary value by the window shift value; and
calculating a current jitter value using a difference between the upper boundary value and the lower boundary value.
2. The method of claim 1 wherein if the upper boundary impact density is greater than the lower boundary impact density, the window shift value is calculated by subtracting the upper boundary value from the current packet delay.
3. The method of claim 1 wherein if the lower boundary impact density is greater than the upper boundary impact density, the window shift value is calculated by subtracting the current packet delay from the lower boundary value.
4. The method of claim 1 further comprising:
for a first PCR value received, calculating an initial current packet delay by subtracting the STC value of the MPEG receiver from the PCR value; and
setting the upper boundary value and the lower boundary value equal to the initial current packet delay.
5. The method of claim 1 further comprising, for each PCR value received:
if the current packet delay is greater than the upper boundary value, recognizing an upper boundary impact; and
if the current packet delay is lower than the lower boundary value, recognizing a lower boundary impact.
6. The method of claim 1 wherein updating the upper boundary impact density or the lower boundary impact density comprises:
incrementing the upper boundary impact density when the current packet delay is greater than the upper boundary value; and
incrementing the lower boundary impact density when the current packet delay is lower than the lower boundary value.
7. The method of claim 1 wherein updating the upper boundary impact density or the lower boundary impact density comprises:
incrementing a density integration counter;
if the density integration counter is greater than a predetermined density integration window value, resetting the density integration counter and the upper boundary impact density and the lower boundary impact density to zero.
8. The method of claim 1 further comprising:
using the current jitter value, dynamically adapting a size of an internal buffer of the MPEG receiver.
9. The method of claim 8 wherein the step of dynamically adapting is performed after a channel change to a selected channel, and before a first video frame of the selected channel is displayed.
10. The method of claim 8 wherein the step of dynamically adapting is performed for a current channel after a glitch due to streaming data unavailability.
11. A non-transitory computer-readable medium comprising instructions for estimating jitter in an MPEG receiver, which, when executed by a processor, cause the processor to perform steps comprising:
receiving an MPEG transport stream comprising a plurality of packets, wherein at least one of the plurality of packets comprises a program clock reference (PCR) value; and
for each PCR value received:
calculating a current packet delay by subtracting a system time clock (STC) value of the MPEG receiver from the PCR value;
if the current packet delay is greater than an upper boundary value, updating an upper boundary impact density or if the current packet delay is less than a lower boundary value, updating a lower boundary impact density
comparing the upper boundary impact density and the lower boundary impact density;
if the upper boundary impact density is greater than the lower boundary impact density, and if the current packet delay is greater than the upper boundary value, incrementing the upper boundary value and the lower boundary value by a window shift value;
if the upper boundary impact density is greater than the lower boundary impact density, and if the current packet delay is less than the lower boundary value, setting the lower boundary value to the current packet delay;
if the lower boundary impact density is greater than the upper boundary impact density, and if the current packet delay is greater than the upper boundary value, setting the upper boundary value to the current packet delay;
if the lower boundary impact density is greater than the upper boundary impact density, and if the current packet delay is less than the lower boundary value, decrementing the upper boundary value and the lower boundary value by the window shift value; and
calculating a current jitter value using a difference between the upper boundary value and the lower boundary value.
12. The non-transitory computer-readable medium of claim 11 , the steps further comprising:
for a first PCR value received, calculating an initial current packet delay by subtracting the STC value of the MPEG receiver from the PCR value; and
setting the upper boundary value and the lower boundary value equal to the initial current packet delay.