Win8 brings more excellent video/audio enjoyment to users.

Computer Store News Microsoft is committed to bringing more excellent video/audio enjoyment to users in Win8. In the official Windows8 blog, Microsoft Media Platform and Technology The team's project manager, Scott Manchester, writes about Microsoft's development work behind music and video playback improvements. In many cases, these improvements made by Microsoft will increase battery life or improve performance.

For example, audio data will be processed in batches/blocks. This mechanism will improve CPU performance and save battery. Microsoft Win8 introduces a better bit rate system, the initial video stream will use a lower rate during video buffering, and Win8 will also adopt a new content mixing system. In most cases, the priority video playback from the app in Windows is in the foreground, and the video stream will slow down as the user moves the app to the background. In fact, when the music playback is placed in the background, it can still be played to the maximum volume.

The figure below shows a comparison between the average CPU utilization of Windows 7 and Windows 8, playing 720P VC1/H.264 video clips and camera capture preview. Video playback and camera capture preview, Win8 CPU usage will be less than half of Win7, both fast and power-saving. According to the EIA /TIA920 standard, it can be concluded that only one-way audio delay of the media processing pipeline can not exceed 100ms in order to achieve an available real-time communication experience. Taking this into account, we designed a test environment to measure the end-to-end delay of the pipeline, as shown in the following figure:

Delay in measuring the delay, it takes a video frame of the camera to be captured, then Encoding the supported video format in the case of video communication, eventually to the terminal or "glass-glass" channel, the network loopback interface decodes, flows through, and finally displays the rendering. In the numbers below, you can see the results of the medium in the pipeline when the PCM audio is captured and rendered in low latency mode. The first set of spikes correspond to the original speech of the transmitter and the second set of those words that are displayed at the receiver. The delay between the two is 65MS, well below the 100ms target.

The following figure shows the comparison of playback and communication optimization modes of video frames captured during pipeline delay, encoding (H.264 format), streaming, decoding, and then displayed in various resolutions. The overall delay of 145ms (as perceived by the available TIA /EIA920 for real-time video calls) is to display the green line on the chart.

In playback mode, the average delay of the pipeline is approximately 575ms. This delay is a consumer video that is necessary for a smooth playback experience, but real-time video communication is unacceptable. On the other hand, in the low latency mode, the measurement delay is the target of each measured video resolution.
Subtitle and video playback in Windows8 Multi-track video playback effect in Windows8

It can be seen that Microsoft has made great efforts in Windows8, with less delay in video notification and lower power consumption. Working with a high-definition camera will give you a better chat experience. In the video aspect, a 3D stereo effect is added, and at the same time, multiple tracks are played.