1.-10. (canceled)
11. One or more computer-readable storage media having stored thereon computer-executable instructions for causing a computing system programmed thereby to perform a method comprising:
encoding an image using a video encoder, including, for a current coding unit (CU) of the image:
encoding the current CU, the current CU having a prediction unit (PU); and
based at least in part on (a) range of pixel values in the current CU and (b) number of bits used to code the current CU, determining whether to split the current CU into smaller CUs andor smaller PUs for encoding; and
outputting the encoded image as part of a coded bit stream.
12. The one or more computer-readable storage media of claim 11 wherein the image is a still image, and wherein the method further comprises:
setting CU size to be less than maximum CU size;
setting CU depth to be less than maximum CU depth; and
disabling residual quadtree coding, such that transform unit (TU) size equals PU size.
13. The one or more computer-readable storage media of claim 11 wherein the range of pixel values is a difference between a maximum pixel value in the current CU and a minimum pixel value in the current CU, and wherein the determining whether to split the current CU includes comparing the range of pixel values to a range threshold.
14. The one or more computer-readable storage media of claim 13 wherein the range threshold depends at least in part on size of the current CU.
15. The one or more computer-readable storage media of claim 11 wherein the determining whether to split the current CU includes comparing the number of bits used to code the current CU to a bits threshold.
16. The one or more computer-readable storage media of claim 13 wherein the bits threshold depends at least in part on size of the current CU.
17. The one or more computer-readable storage media of claim 14 wherein the encoding the image further includes, for a particular PU of the image, determining an intra prediction mode for the particular PU using a gradient mode histogram.
18. The one or more computer-readable storage media of claim 11 wherein the encoding the image further includes, for a particular PU of the image, determining an intra prediction mode for the particular PU using a hierarchical prediction scheme with a coarse-to-fine decision-making process for intra angular prediction modes.
19. The one or more computer-readable storage media of claim 11 wherein the encoding the image further includes, for a particular PU of the image:
calculating a spatial frequency measure (SFM) for the particular PU; and
determining whether to use a transform for the particular PU based at least in part on the SFM for the particular PU.
20. The one or more computer-readable storage media of claim 19 wherein the determining whether to use the transform includes:
comparing the SFM for the particular PU to a SFM threshold;
if the SFM for the particular PU is below the SFM threshold, using the transform for the particular PU; and
otherwise, performing rate-distortion optimization (RDO) with respect to using or skipping the transform for the particular PU.
21. A method comprising:
encoding an image using a video encoder, including, for a particular prediction unit (PU) of the image, determining an intra prediction mode for the particular PU using, depending at least in part on size of the particular PU, either a gradient mode histogram or a hierarchical prediction scheme; and
outputting the encoded image as part of a coded bit stream.
22. The method of claim 21 wherein the intra prediction mode for the particular PU is determined using the gradient mode histogram, including:
calculating gradients for at least some pixel values of the particular PU;
building the gradient mode histogram using the calculated gradients;
selecting candidate modes using the gradient mode histogram;
checking distortion and bits for each of the candidate modes and one or more other modes, to identify a best mode; and
checking the best mode and any most probable modes (MPMs) using rate-distortion optimization (RDO), to identify the intra prediction mode for the particular PU.
23. The method of claim 22 wherein each of the calculated gradients includes amplitude and direction, and wherein the building the gradient mode histogram includes:
for each of the calculated gradients, mapping a perpendicular direction for the direction of the calculated gradient to an intra angular prediction mode; and
for each of multiple intra angular prediction modes represented in the gradient mode histogram, summing the amplitudes of the calculated gradients mapped to that intra angular prediction mode.
24. The method of claim 21 wherein the intra prediction mode for the particular PU is determined using the hierarchical prediction scheme, including:
in a first round, checking distortion and bits for each of multiple candidate intra angular prediction modes, to identify winner modes of the first round;
in a second round, checking distortion and bits for (a) neighboring intra angular prediction modes of the respective winner modes of the first round and (b) one or more other modes, to identify a best mode of the first and second rounds; and
checking the best mode of the first and second rounds and any most probable modes (MPMs) using rate-distortion optimization (RDO), to identify the intra prediction mode for the particular PU.
25. The method of claim 24 wherein the one or more other modes include a planar mode andor a DC mode, and wherein the MPMs are derived from neighbor PUs.
26. The method of claim 21 wherein the encoding the image further includes, for the particular PU:
calculating a spatial frequency measure (SFM) for the particular PU; and
determining whether to use a transform for the particular PU based at least in part on the SFM for the particular PU.
27. The method of claim 26 wherein the determining whether to use the transform includes:
comparing the SFM for the particular PU to a SFM threshold;
if the SFM for the particular PU is below the SFM threshold, using the transform for the particular PU; and
otherwise, performing rate-distortion optimization (RDO) with respect to using or skipping the transform for the particular PU.
28. A computing device comprising one or more processors and one or more computer-readable storage media having stored thereon computer-executable instructions for causing the computing device to perform a method comprising:
encoding an image using a video encoder, including, for a particular prediction unit (PU) of the image:
calculating a spatial frequency measure (SFM) for the particular PU; and
determining whether to use a transform for the particular PU based at least in part on the SFM for the particular PU; and
outputting the encoded image as part of a coded bit stream.
29. The computing device of claim 28 wherein the determining whether to use the transform includes:
comparing the SFM for the particular PU to a SFM threshold;
if the SFM for the particular PU is below the SFM threshold, using the transform for the particular PU; and
otherwise, performing rate-distortion optimization (RDO) with respect to using or skipping the transform for the particular PU.
30. The computing device of claim 28 wherein the SFM for the particular PU indicates activity level within the particular PU, and wherein the calculating the SFM for the particular PU includes:
calculating average horizontal differences between pixel values of the particular PU;
calculating average vertical differences between pixel values of the particular PU; and
determining the SFM for the particular PU using the average horizontal differences and the average vertical differences.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A DC-to-DC converter, comprising:
a power switch unit;
an amplifier that compares a feedback voltage to a reference voltage and outputs an error signal;
a comparator that compares the error signal to a ramp signal and outputs a comparison signal;
a PWM controller that receives the comparison signal and outputs a digital control signal, wherein the digital control signal is used to control the power switch unit such that the DC-to-DC converter supplies a regulated voltage onto a load; and
a control signal monitoring circuit that monitors the digital control signal, wherein the control signal monitoring circuit detects a light load condition and in response outputs a first enabling signal such that the DC-to-DC converter operates in a power-save mode.
2. The DC-to-DC converter of claim 1, wherein the control signal monitoring circuit detects a heavy load condition and in response outputs a second enabling signal such that the DC-to-DC converter operates in a normal operation mode.
3. The DC-to-DC converter of claim 2, wherein the DC-to-DC converter consumes less power in the power-save mode than in the normal operation mode.
4. The DC-to-DC converter of claim 2, wherein the comparator has a substantially smaller power consumption in the power-save mode than in the normal operation mode.
5. The DC-to-DC converter of claim 2, wherein the power switch unit comprises a switch and a current amplifier, and wherein the current amplifier has a substantially smaller power consumption in the power save mode than in the normal operation mode.
6. The DC-to-DC converter of claim 1, wherein the control signal monitoring circuit comprises:
a timer that monitors the digital control signal and outputs a digital value when the digital control signal remains unchanged for a predetermined time period; and
a sequential logic element that outputs the first enabling signal in response to the digital value.
7. The DC-to-DC converter of claim 6, wherein the sequential logic element outputs the second enabling signal when the digital control signal changes from a digital low to a digital high.
8. The DC-to-DC converter of claim 6, wherein the sequential logic element is taken from the group consisting of: a flip-flop circuit, and an SR latch circuit.
9. The DC-to-DC converter of claim 1, wherein the DC-to-DC converter further comprises a synchronous rectifier.
10. A method, comprising:
(a) monitoring a digital control signal generated by a PWM controller of a DC-to-DC converter, wherein the DC-to-DC converter supplies a regulated voltage onto a load;
(b) detecting that the DC-to-DC converter is operating in a light load condition based on characteristics of the digital control signal; and
(c) in response to the detecting in (b), outputting a first enabling signal such that the DC-to-DC converter operates in a power-save mode.
11. The method of claim 10, wherein the light load condition is detected in (b) by determining that the digital control signal remains unchanged for a predetermined time period.
12. The method of claim 10, further comprising:
(d) detecting that the DC-to-DC converter is operating in a heavy load condition based on the characteristics of the digital control signal; and
(e) in response to the detecting in (d), outputting a second enabling signal such that the DC-to-DC converter operates in a normal operation mode.
13. The method of claim 12, wherein the heavy load condition is detected in (d) by determining that the digital control signal changes from a digital low to a digital high.
14. The method of claim 12, wherein the DC-to-DC converter consumes less power in the power-save mode than in the normal operation mode.
15. The method of claim 12, wherein the DC-to-DC converter comprises a synchronous rectifier.
16. A DC-to-DC converter comprising:
a power switch unit;
a controller that outputs a digital control signal such that the power switch unit supplies a regulated voltage onto a load; and
means for monitoring the digital control signal, wherein the means detects a light load condition based on characteristics of the digital control signal and in response outputs a first enabling signal such that the DC-to-DC converter operates in a power-save mode.
17. The DC-to-DC converter of claim 16, wherein the light load condition is detected by determining that the digital control signal remains unchanged for a predetermined time period.
18. The DC-to-DC converter of claim 15, wherein the means also detects a heavy load condition based on the characteristics of the digital control signal and in response outputs a second enabling signal such that the DC-to-DC converter operates in a normal operation mode.
19. The DC-to-DC converter of claim 18, wherein the heavy load condition is detected by determining that the digital control signal changes from a digital low to a digital high.
20. The DC-to-DC converter of claim 18, wherein the DC-to-DC converter consumes less power in the power-save mode than in the normal operation mode.
21. The DC-to-DC converter of claim 16, wherein the DC-to-DC converter comprises a synchronous rectifier.