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Recent media technologies like Blu-ray* have driven increased viewing of HD content on mobile computers. Correspondent interests have developed in exploring more power opportunities and creating context power awareness that can extend battery life. This white paper analysis validates two hours or more of HD video playback on an Intel-based platform and focuses on the impact of different software playback local power profiles while running various HD Blu-Ray* codecs. The analysis provides recommendations to help create HD energy efficient software and make mobile systems more power aware.

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Background

Platform Power Profile
As a precursor to our research, it is important to understand how energy is being consumed in the mobile computer. The power profile provides a model of various components on a mobile computer (mobile platform). Measurement results vary depending on the usage model. For example, the relative contribution of processor power to the overall platform power will be significant in a CPU-intensive workload, but it will not be a dominant factor while the platform is idling. Furthermore, it may also vary depending on whether hardware acceleration is enabled or disabled, as well as the type of codecs that are used in case of video playback. These cases are studied in the scope of the paper.
Figure 1 shows how the power profile can vary during various usage models. For this particular profile, the CPU, memory, and file system tests were run using SiSandra benchmarks (http://www.sisoftware.co.uk) . Note that the platform power in Figure 1 does not include LCD since we have excluded it from our analyses due to the fact the monitor has its own external power supply. (Others include WLAN, HD-Audio, mini-card, ICH, and other peripherals.)

Figure 1. Platform Power Profile



Testing Methodology

Two HD video playback applications were tested on our in-house Software Development Platform (SDP) (Intel® Core™2 Duo Mobile Penryn Processor T9400). The SDP was instrumented for power measurement/characterization. The playback applications were characterized while playing three different video titles, each with a different high definition encoding format. We also tested the two applications while enabling video Hardware Acceleration via Video Hardware Configuration mode within the applications for each workload.

White Paper Goals
The goals of this paper are:

• To validate 2+ hours of HD Video playback on an Intel–based "Cantiga" platform equipped with hardware accelerated video decode.
• To understand the impact of software playback application local power plans on creating energy efficient software and extending the battery life.

The Workload
The workloads used for power analyses on the Intel® SDP were two common HD Video playback applications while each application was playing one of the following video titles with their video configurations:

• "RV" – encoded in MPEG-2 & Bitrate: 40.000 Mbps
• "300" – encoded in VC-1 & Bitrate: 29.999 Mbps
• "Casino Royale" – encoded in H.264 & Bitrate: 33.000 Mbps

All tiles use the following video configurations

• Framerate: 23.976 Hz
• Resolution: 1920x1080
• Aspect ratio: 16x9
• xvYCC Stream: No

Configuring the Experiment

The experiment configuration settings were as follows:

• Storage: Blu-ray* discs
• Optical Drive: Panasonic* Notebook SATA Blu-ray* drive
• Memory: 2GB (2X1 GB) DDR3 1066MHz
• CPU: T9400 @2.53 GHz Intel® Core™2 Duo Mobile (Penryn) Processor
• Chipset Video mode was set to VLD (Default Setting).
• HDD 80 GB SATA* Mobile HD 7200 RPM
• Operating System: Microsoft Windows Vista* 32bit
• Vista* Power Plan: Balanced
• Screen mode: Full Screen
• Battery Level: 100% at start of each test
• Testing Time & Nature: 5+ minutes per title starting at Chapter 1 for each test run

HD Video Playback Applications

The graphs in each video playback application section below describe the power characterization results for the applications while running on the Intel® engineering system. Time was measured in milliseconds. Power measurements were acquired using a Fluke NetDAQ* system and corresponding software (v4.0), which reports average power (in watts [W]) which was then converted to total power using application run-time data.

HD Video Playback Application-1
Each study describes our analysis of a leading video playback application. Application-1 comes with a mobile specific pack. Tests were performed under the app’s Maximum Battery and Maximum Performance local application power settings. The hardware acceleration mode in this particular software uses two configurations: 1) Hardware Decode Acceleration and 2) Color Acceleration. We found that operating with hardware acceleration switched on delivered the anticipated power benefits, particularly within the CPU, and that the savings varied by codec.

Figure 2 shows the relative average power consumption of various components in the platform with Intel® integrated graphics hardware acceleration switched on. This configuration clearly shows a reduction in the energy consumption of the CPU (resulting in platform level power savings). The data also shows the impact of two major power plan settings and the impact of various codecs on platform components, in particular the CPU and Blu-ray* drive. The specific data for Figure 2 is shown in Table 1.

Figure 2. Application-1 Blu-ray* HD Video Playback



Table 1. Power Consumption during Application-1 Blu-ray* HD Video Playback

	H.264		VC-1		MPEG2
	MaxBattery	MaxPerf	MaxBattery	MaxPerf	MaxBattery	MaxPerf
Blu-ray Drive	3.32	3.57	3.74	3.74	2.56	1.40
HDD	1.66	1.88	1.60	1.61	1.69	1.55
CPU	2.23	2.29	3.26	3.22	2.21	2.41
Memory	2.09	2.29	2.33	2.32	1.83	1.91
GMCH	4.55	4.79	4.99	4.88	4.52	4.55
Platform	19.29	20.06	21.18	21.05	16.34	17.65
LCD Display	Not instrumented

 

From the data in Table 1, we easily see that there is a slight difference between application-1’s two power plan settings, Maximum Battery (MaxBattery) and Maximum Performance (MaxPerf), on platform power components. The greatest total platform power consumption occurred with VC-1 decoding at 21.18W with MaxBattery and 21.05W with MaxPerf. On the other hand, the lowest total platform power consumption occurred with MPEG2 at 16.34W with MaxBattery 17.65W. In the case of H.264, total platform power was at 19.29W with MaxBattery and 20.06W with MaxPerf.

Observations from this study:
1. Various codecs differ considerably in their computational demands and corresponding power consumption. MPEG-2 is the easiest to decode, followed by VC-1, and then H.264, which is the most complex encoding format.

1.1 There was no significant difference seen between H.264 and VC-1 encodings.
1.2 VC-1 decoding was the highest in power consumption despite the fact H.264
is more computing intensive.
1.3 In the case of MPEG2, Blu-ray* Drive power consumption was the lowest
compared to VC-1 and H.264, which suggests MPEG2 may have been
performing a device content caching or data buffering.

2. The power savings due to hardware acceleration come almost completely from the power saved in the CPU. For example, with hardware acceleration on, the CPU power consumption was in the range of ~ (2.2W-3.2W) for all encodings and the different power settings resulted in significant reduction on total platform power in the range of ~ (16.3W-21.2W). Therefore, most of the savings came from the CPU with some additional savings from the memory and chipset.

3. The data surprisingly showed MaxBattery local power setting having marginal impact on platform power components compared to the MaxPerf power setting. Also, in the case of VC-1 decoding, MaxBattery ironically had higher energy consumption than MaxPerf.

HD Video Playback Application-2

Application-2 is another industry leading video playback application. It also offers special mobile features to enhance battery life for video playback on mobile platforms. Tests were performed with application local power settings Maximum Battery (MaxBattery) and Maximum Performance (MaxPerf). As indicated earlier, one of the primary aims of this paper is to study the impact of these applications local power plans on the platform to reach 2+ hours of playback.

Figure 3 shows the platform power consumption. As with Application-1, all decoding was power hungry and higher in particular with H.264 and VC-1 decoding. Once again, significant differences were not seen between Application-2 local power settings except in the case of MPEG2 encoding.

Figure 3. Application-2 Blu-ray* HD Video Playback



Table 2. Power Consumption during Application-2 Blu-ray* HD Video Playback

	H.264		VC-1		MPEG2
	MaxBattery	MaxPerf	MaxBattery	MaxPerf	MaxBattery	MaxPerf
Blu-ray Drive	3.55	3.47	3.74	3.66	2.85	1.88
HDD	1.37	1.54	1.28	1.56	1.27	1.57
CPU	3.97	3.95	3.72	3.78	3.87	3.88
Memory	1.99	1.96	1.86	1.93	1.39	1.36
GMCH	4.74	4.71	4.83	4.84	4.38	4.27
Platform	20.88	21.57	21.47	21.48	17.67	19.71
LCD Display	Not instrumented

Observations from this study:
1. There was no significant difference seen on total power consumption between H.264 and VC-1 encodings for both local power settings.
2. In the case of MPEG2, Blu-Ray* Drive power consumption was the lowest compared to VC-1 and H.264, which suggests MPEG2 may be utilizing device content caching or data buffering (similar to the observation in Application-1).
3. Again, the data surprisingly showed MaxBattery local power setting was having marginal impact on platform power components compared to MaxPerf. Except for the case of MPEG2, 2.04W was the difference between the MaxBattery and MaxPerf power setting.

Summary

This section summarizes our findings with particular focus on the impact of Intel® integrated graphics, the support of Intel® Cantiga chipset native hardware accelerator of HD Blu-ray* contents , and the local applications power plan settings and various decoders on the overall total platform power saving.

Figure 4. Total Platform Power Consumption during Blu-ray* HD Video Playback



Table 3. Total Platform Power Consumption during Blu-Ray* HD Video playback

	H.264		VC-1		MPEG2
	Application-1	Application-2	Application-1	Application-2	Application-1	Application-2
Platform-MaxPerf	20.06	21.57	21.05	21.48	17.65	19.71
Platform-MaxBatt	19.29	20.88	21.18	21.47	16.34	17.67

Figure 4 and Table 3 focus on Application-1 and Application-2 local plan power settings (MaxPerf and MaxBattery) and provide a relative comparison of the total platform energy consumed by the applications with Intel® integrated HW accelerator set to on all the time during all tests:

• Application-1 is the most energy efficient software on both MaxPerf and MaxBattery Power settings for all encodings H.264, VC-1 & MPEG2.
• MPEG2 encoding significantly consumed less power on Application-1 and Application-2 when compared to H.264-2 and VC-1 encoding. This holds true regardless of application power plan settings.
• VC-1 encoding is the most costly encoding in the study on both applications. We find it interesting in the study that there is slight difference with VC-1 encoding on both applications regardless the power plan settings comparing to MPEG2 and H.264.
• As indicated early in this paper, there is no significant difference seen on the overall total platform power when plan power is set to MaxPerf on each application for H.264 and VC-1 encodings. Surprisingly, this also holds true that there is no difference between the two applications except in the case of MPEG2.
• As indicated before, LCD was not instrumental in this study. From a side power study on the impact of LCD brightness level, full brightness can consume around 5-6 watts, and 50% brightness can consume 3-4 watts. This also depends on LCD configuration such as bit rate and size.
• The Table 3 and Figure 4 data above clearly shows the overall total platform power consumed between 16 Watts and 22 Watts for all encodings. This data supports and proves that two hours of HD video playback can easily be reached in all encodings on Intel® Cantiga chipset, in particular with MPEG2 encoding with respect to LCD brightness level and battery size.

In conclusion, Figure 4 and Table 3 show a comparative analysis for all applications used in this power study. Application-1 is the most energy-efficient HD video playback software for encoded content. And also, since we see throughout the analysis that there is no significant difference between the two HD applications, we use Table 4 to demonstrate through Application-1 that two hours or more of HD video playback can be reached and validated on the Intel® Cantiga chipset with regard to battery capacity and LCD brightness level.

Table 4. Application-1 Anticipated Time for Different Battery Size and LCD Brightness Level during Blu-ray* HD Video Playback

	1	2	3	4	5	6	7
Encoding	Application-1 Maximum Battery Total Platform (W)	Total platform at 100% LCD (~6W) Brightness	Total platform at 50% LCD (~3W) Brightness	Anticipated Time at 54 WHr Battery + 100% Brightness	Anticipated Time at 60 WHr Battery + 100 % Brightness	Anticipated Time at 54 WHr Battery + 50% Brightness	Anticipated Time at 60 WHr Battery + 50% Brightness
H264	19.29	25.29	22.29	2.14 Hr	2.37 Hr.	2.42 Hr.	2.69 Hr.
VC-1	21.18	27.18	24.18	1.99 Hr	2.21 Hr.	2.23 Hr.	2.48 Hr.
MPEG2	16.34	22.34	19.34	2.42 Hr	2.69 Hr.	2.79 Hr.	3.10 Hr.

Recommendations

The study above shows comparative analysis of HD Video playback applications power profiles and the significant effects of running various HD codecs on Intel® Cantiga with native HW Accelerator support, and particularly the energy saved in the CPU and the overall total platform that helped extend battery life compared with an earlier HD Video playback white paper power study .

This section makes some recommendations that will help make HD video playback applications Hardware and OS power aware, reducing energy consumption to help extend HD playback time on mobile computers.

Improving HD Application Power-Awareness:

Video playback developers highly recommend working on the following areas to help extend and create energy efficient applications:

• Power Management Schema: Experiment and research more on their local power management schema since the paper surprisingly shows marginal differences in both H264 and VC-1 encodings on each application local power schema (independent from Vista* power plan).
• Power-Awareness Application: Applications should respond to appropriate OS power events and also shut down non-essential functions that may increase battery energy consumption, i.e., many applications use SetTimer() to invoke particular functionality after a specific time interval.
• Explore Device Buffering: Explore device buffering and content caching for VC-1 and H.264 without having any side performance risk or penalty on loading high intensive computation in the cache. Table 1 and Table 2 show Blu-Ray* Optical Drive power consumptions are below 3 Watts with MPEG encoding that may suggest data efficiency and device buffering .
• Optimizing the Application: Both applications in this paper use SSE2 and SSE3 micro-architecture. We therefore recommend that developer’s video playback applications take steps to optimize software decoders to take advantage of hyper threading, multiple cores, and special instruction sets such as Intel SSE4X and AVX that may help significantly optimize the application. There are also data efficiency techniques such as memory buffering and caching that can further improve energy-efficiency.

Investing in Hardware Power-Awareness:
This paper shows the effect of upgraded hardware such as battery, chipset and CPU on saving power consumption compared to an early power study done on HD video playback. Therefore, OEMs should highly consider investing in and designing on not only the state of the art mobile PCs but also notebook PCs that can last longer in the following areas:

• Make Better Batteries:
  Battery life is a key differentiator in notebook PCs. Therefore, OEMs should increase the adoption of notebook PCs that require focus on longer battery life with high quality and capacity that can go all day on a single charge.
• Adapting Energy-Efficient Hardware:
  This paper clearly demonstrates the significant impact of Intel–based "Cantiga" platform equipped with hardware accelerated video decoders (Penryn CPU) on power saving compared to Intel-based "Matanzas" platform (Merom CPU). OEMs are highly recommended to continue investment in Intel® consumer platforms, both mobile and desktop, which include energy-efficient devices. In particular, 45nm processor technology (Nehalem) and dedicated hardware accelerators for high-definition video decoding. These new platform architectural changes will reduce CPU and total platform power and boost performance. In addition, Nehalem processors have Quad cores to support multi-threading and Intel® SSE4 and AVX instructions to enhance performance.

Configuring and Utilizing OS Settings Efficiently:

Power management schema definitions may vary between platforms. It also holds true
that each platform has different energy use profiles. We find it interesting that some
OS configurations and settings can make a difference on power saving. Therefore, we
recommend the following to help extend battery life:

• Selecting Appropriate OS Power Plan:
  Each platform has different power profile settings that can be changed by the end user. These power settings can differentiate CPU performance and energy-efficiency with respect to CPU frequency. Therefore, before choosing your workload, it’s highly recommended to select the appropriate power plan and power sources such as AC/DC that can have an impact on the overall platform performance and power saving. Also, MS Vista* "Balanced" power profile allows Intel® SpeedStep™ technology and the OS to dynamically change the CPU frequency on demand. Also, it’s recommended to:
• Shut down OS unnecessary functions or features:
  For OEMs, and ultimately for consumers, OS Vendors (OSV) continue to develop OS features and tools that can make notebook PCs energy efficient and power aware. An effective energy efficient OS should monitor and measure any running process with respect not only to its performance but also to its power behavior. It’s been proven from this paper and other power studies, that video player, Web Media, Screen Saver, system update, Scan, Disc defragmentation, LCD Brightness level and more can impact overall power consumption. Thus, having a system with tools and gadgets that can be aware of the system power source and its status so that the behavior can be changed dynamically, or alerts end user to take an early action against any source of unnecessary running tools/features in order to save power, delivers the best possible user experience.

Conclusion

This analysis clearly shows the importance of the Intel® native hardware accelerator. Intel® Mobile Chipset "Cantiga" with its hardware accelerated HD video decode saves energy and validates two hours or more of HD video playback based on the battery capacity, LCD brightness level and software decoders. We have also shown that despite the difference in software decoders, the HD video playback applications show no significant differences in their local power management profiles regardless if power profile setting has been set to Maximum Battery or Maximum Performance. Software decode energy-efficiency can be improved by researching more on their local power schema, using advanced micro architecture instructions, multi-threading, efficient algorithm, and date efficiency. With these approaches in consideration, also having notebook PCs with hardware and OS power awareness, playback time on mobile devices can be extended enough to play an entire HD movie on a single charge from a standard battery.

References

[1] Tareq Darwish, Rajshree Chabukswar, Kiefer Kuah and Bob Steigerwald, HD Video Playback Power Consumption Analysis, http://software.intel.com/en-us/articles/hd-video-playback-power-consumption-analysis
[2] Rajshree Chabukswar and Jun De Vega, Power Enabling with Windows Vista* on Intel® Laptop Platform, http://software.intel.com/en-us/articles/power-enabling-with-windows-vista-on-intel-laptop-platforms
[3] Bob Steigerwald, Rajshree Chabukswar, Karthik Krishnan and Jun De Vega, Creating Energy-Efficient Software http://software.intel.com/en-us/articles/creating-energy-efficient-software-part-1/
[4] Rajshree Chabukswar, DVD Playback Power Consumption Analysis [1] http://software.intel.com/en-us/articles/dvd-playback-power-consumption-analysis/
[5] Aleksandr Budik, 45-nm Penryn and Nehalem: architectural details, http://www.digital-daily.com/cpu/intel_penryn_nehalem/

About the Authors

Tareq Darwish is a Software Engineer working on Platform Power Enabling as part of client enabling in the Software Solutions Group. His current focus is on defining tools and technologies to support the development of energy-efficient software for Intel-based mobile platforms. Prior to working at Intel, he worked for nine years with Lexmark International in Lexington, Kentucky as a Software Development Engineer. He earned his MS degree in Applied Computing and Software Engineering at Eastern Kentucky University. His email is tareq.h.darwish@intel.com

Rajshree Chabukswar is a Software Engineer working on enabling client platforms through software optimizations in the Software Solutions Group. Prior to working at Intel, she obtained a Masters degree in Computer Engineering from Syracuse University, NY. Her email is rajshree.a.chabukswar@intel.com.

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