"The power consumption of hard decoding is much lower than that of software!" I believe this is the impression that most people have of hard decoding and soft decoding. But how much lower is it? Few people can give the answer. In order to uncover the mystery of this problem, the Peking University Digital Media Research Center specially used a power consumption meter for testing. In terms of mobile phone video playback, hard decoding based on dedicated chips has become the preferred solution for mobile phone video decoding due to its fast speed and low power consumption. However, the long deployment period and slow iteration speed of hard decoding chips have restricted the speed of upgrading mobile phone video coding technology to a considerable extent. In recent years, with the continuous enhancement of the general processing capabilities of smart phones, software decoding has gradually become popular due to its easy deployment. So, how big is the power consumption advantage of hard decoding over soft decoding? With this question in mind, we selected several typical mobile phones to test one of H.264/AVC hard decoding, H.264/AVC soft decoding, H.265/HEVC hard decoding, H.265/HEVC soft decoding and AVS2 soft decoding. An important phenomenon has been discovered: the power consumption advantage of hard decoding over soft decoding is gradually being lost. In recent years, smartphones produced in recent years have been hard-decoded and soft-decoded on mainstream 720P (1280x720) and smaller resolution videos. The power consumption difference of the solution is already very small. This means: The update iteration speed of the video coding technology on the mobile phone will be greatly accelerated. The following describes the test process and results in detail. Hardware decoding depends on the terminal chip. Smart phones generally support H.264/AVC hardware decoding; mobile phones that support HEVC/H.265 hardware decoding are not fully popular. Take Apple phones as an example. Apple phones before iPhone 6S do not support it. HEVC hard decoding; AVS2 currently lacks hard decoding support in mobile terminals. In terms of soft decoding, FFMPEG has built-in H.264 and H.265 software decoding libraries; our team has developed the AVS2 soft decoding library-uAVS2d, which supports mobile phone applications, which can realize real-time decoding of 1080P video on smartphones [1]. The following experiments test the power consumption performance of different software and hardware solutions on different grades of mobile phones. 1. Test conditions 1) Test video The test video includes 5 video clips of different scenes, covering indoor scenes, outdoor sports, natural scenery, interviews and other scenes. The test videos are divided into three groups, which are respectively coded with H.264, HEVC and AVS2. The three groups of videos come from the same video source, and the video coding quality of the same resolution is similar. The specific video specifications are as follows: 2) Test model 3) Test tool Power consumption test tool: Monsoon Power Monitor AAA10F Video player: ijkplayerdemo Software decoder: FFmpeg built-in H.264 and HEVC decoder; uAVS2d decoder [2]. 2. Test method 1) Configure the test environment a) Samsung S3: Remove the battery, power the phone and connect the computer with the power monitor, set the output voltage to 3.7V, and use the Main channel to test the data. b) iPhone: Use USB to connect to the power monitor, and test the charging power when fully charged. The charging power is approximately the power consumption. 2) The phone turns on the airplane mode, connects to the WIFI network, clears all background processes, the brightness is fixed to half of the maximum brightness, and it is muted. 3) Keep the standby state first and wait for the fluctuation of the mobile phone power consumption data to stabilize. 4) Conduct a set of tests a) Start the recording program of the power consumption tester; b) Wait for 100s to open a group of network test videos (5min); c) Wait for 100s after the video playback ends; d) Export power consumption data, calculate the average power consumption before and after 100s and the average power consumption for 5 minutes of video playback. 5) Repeat 4) test five sets of data (H.264 hard solution, H.264 soft solution, H.265 hard solution, H.265 soft solution and AVS2 soft solution). 6) Replace the phone, repeat 1)-5), and test Samsung S3, iPhone 6 Plus, iPhone 6S, iPhone 8 in turn. 3. Test results the data shows 1) Total power consumption refers to the power consumption of the mobile phone during video playback. 2) Standby power consumption refers to the power consumption of the mobile phone when the mobile phone is on and without operation. 3) The test video is a network stream. Because the player has a data buffer (15MB), the download will end early. The network download has a certain impact on power consumption. 4. Analysis of test results With the improvement of the general processing capabilities of smartphones, the power gap between software and hardware solutions has gradually narrowed. For 720P video, the power consumption of H264 software and hardware solutions in iPhone 8 is only 14% different, while the AVS2 software solution is only compared with the H264 hard solution. 8% higher power consumption. The power consumption of different software decoding schemes is quite different. Among the three schemes tested, the AVS2 soft decoding scheme has the lowest power consumption. Compared with the H.264 soft decoding scheme, because AVS2 has higher compression efficiency and the same quality video, the AVS2 coding rate can be 40% lower than H.264, and the lower bit rate brings lower decoding complexity and network overhead. . Since we are testing the open source HEVC soft decoder, the calculation efficiency is average, so the power consumption of the HEVC soft solution is relatively high. Video resolution has a large difference in power consumption for soft decoding. As shown in Table 2, taking iPhone 8 as an example, for 480P (640x480) video, the power consumption of AVS2 soft decoding and H.264 hard decoding are equivalent; for 720P video, AVS2 software The power consumption of decoding is 8% higher than that of H.264 hard decoding; for 1080P video, the power consumption of AVS2 soft decoding is only 11% higher than that of H.264 hard decoding. It should be pointed out that the power consumption of soft decoding has a great correlation with specific implementation schemes. With the continuous optimization of soft decoding schemes, the power consumption gap with hard decoding will be further reduced. to sum up With the enhancement of the general computing power of smartphones, the power consumption difference between soft solution and hard solution for mainstream mobile phones in mainstream video resolutions such as 480P and 720P has been very small, which means that mobile phone video decoding depends on the support of dedicated chips. , The speed of mobile video technology iteration will be greatly accelerated. â—High-efficiency, energy-saving design, full display of green concept from inside to outside High efficiency rectifier Changzhou Changyuan Electronic Co., Ltd. , https://www.cydiode.com
The system adopts a high-efficiency rectifier, the peak efficiency of the rectifier is greater than 96.2%, and the power consumption of the rectifier sleep is as low as 4W or less.
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The rectifier adopts DSP+MCU dual digital circuit control mode, the system adopts CAN+RS485 dual bus control, the system power supply reliability is higher, and the transmission rate is faster.