Abstract: A method for assessing quality of a VR video, including: obtaining a bit rate, a frame rate, resolution, and TI of a VR video, and determining a mean opinion score (MOS) of the VR video based on the bit rate, the frame rate, the resolution, and the TI of the VR video. The MOS of the VR video is used to represent quality of the VR video. Further, an assessment apparatus is provided. In the embodiments, accuracy of an assessment result of a VR video can be improved.

Abstract: A video quality assessment method includes obtaining a video quality assessment parameter of a to-be-assessed video, where the video quality assessment parameter of the to-be-assessed video includes an average packet loss gap of the to-be-assessed video, determining packet loss dispersion of the to-be-assessed video based on the video quality assessment parameter of the to-be-assessed video, and determining quality of the to-be-assessed video based on a packet loss rate of the to-be-assessed video, an average consecutive packet loss length of the to-be-assessed video, the packet loss dispersion of the to-be-assessed video, and attribute information of the to-be-assessed video.

Abstract: A video stream switching method includes receiving, by transmission device, a plurality of video streams of a first video and a plurality of video streams of a second video, sending the video streams of the first video through target output ports respectively corresponding to the video streams of the first video, after receiving a switching instruction, determining switching reference information of a reference end-of-frame packet of each video stream of the first video and the second video, determining switching reference information of a switching packet of the video stream, and switching from the video streams of the first video to the video streams of the second video based on the switching reference information of the switching packet of each video stream.

Abstract: A switching device determines a video parameter value of a switching point of a first video stream, and determines a video parameter value of a switching point of a second video stream. The video parameter value includes a timestamp and/or a sequence number. The switching device determines an audio parameter value of a switching point of a first audio stream based on a timestamp of the switching point of the first video stream, and determines an audio parameter value of a switching point of a second audio stream based on a timestamp of the switching point of the second video stream. The audio parameter value includes a timestamp and/or a sequence number. The switching device performs switching based on determined switching points.

Abstract: The invention provides a thin film deposition system and a method, and relates to the field of thin film deposition. The deposition method comprises the following steps: 1) heating metal substrate; carrying out deposition. The method is characterized in the step 1) that a current is conducted into the metal substrate at one end of the growth zone by one electrode, and out of the metal substrate at the other end of the growth zone by the other electrode, so that the metal substrate is heated by the heat emitting of the resistant of the metal substrate itself. According to the method, the quality of the prepared thin film is improved, while the preparation cost of the thin film is reduced. In addition, the consistent double-sided thin films can be easily prepared on two surfaces of the metal substrate by employing the system and method.

Abstract: This application discloses an audio stream switching method and apparatus. After a switching device receives a switching instruction, the switching device determines a synchronization relationship between a switch-in stream and a switch-out stream, determines a parameter value of a switching point of the switch-in stream based on the synchronization relationship and a timestamp of a packet in the switch-in stream, and determines a timestamp of a switching point of the switch-out stream based on the synchronization relationship and a timestamp of a packet in the switch-out stream, and/or the switching device switches a packet that is in the switch-out stream and whose parameter value is greater than the parameter value of the switching point of the switch-out stream to a packet that is in the switch-in stream and whose parameter value is greater than the parameter value of the switching point of the switch-in stream.

Abstract: A method for preparing an ultrathin two-dimensional (2D) monocrystalline nanosheet, the method including: 1) placing BiX3 powder where X=I, Br, or Cl in a crucible, and putting the crucible on a first heating zone of a furnace disposed at a gas inlet of a quartz tube; placing substrates covered with metal sheets on a second heating zone of the furnace disposed at a gas outlet of the quartz tube; 2) vacuumizing the quartz tube; pumping Ar gas into the quartz tube until the air pressure is 101.325 kPa; pumping a carrier gas into the quartz tube; and 3) heating and maintaining the second heating zone; heating the first heating zone for BiX3 evaporation until producing chemical reaction between BiX3 and the metal sheets, and preparing ultrathin 2D nanosheets on the substrates simultaneously; and cooling the substrate naturally to 15-30° C.

Abstract: Embodiments of the present invention disclose a video stream switching method. The method includes: A transmission device receives a plurality of video streams of a first video and a plurality of video streams of a second video; sends the plurality of video streams of the first video through target output ports respectively corresponding to the plurality of video streams of the first video; after receiving a switching instruction, determines switching reference information of a reference end-of-frame packet of each video stream of the first video and the second video, and then determines switching reference information of a switching packet of the video stream; and switches from the plurality of video streams of the first video to the plurality of video streams of the second video based on the switching reference information of the switching packet of each video stream.

Abstract: Disclosed are a method, an apparatus, and a system for implementing video stream switching. The method can determine switching reference information of a first reference frame trailer packet of a first video stream and switching reference information of a second reference frame trailer packet of a second video stream, when receiving a switching instruction; and switch from the first video stream sent through the target egress port to the second video stream based on the switching reference information of the first switching packet and the switching reference information of the second switching packet. Because locations of data packets sent before and after switching are considered during video stream switching, damage caused by a switching operation to a transmitted video image can be effectively reduced.

Abstract: A video service quality assessment method and apparatus are provided to resolve a prior-art problem of relatively low accuracy of an assessment result. A monitoring device obtains an identifier of a to-be-monitored channel, an identifier of to-be-monitored user equipment, and configuration information of a video service transmission system; obtains a multicast video stream of the to-be-monitored channel based on the identifier of the to-be-monitored channel; obtains a retransmitted video stream based on the identifier of the to-be-monitored channel, the identifier of the to-be-monitored user equipment, and the configuration information of the video service transmission system; determines a to-be-assessed video stream based on the multicast video stream and the retransmitted video stream; and parses the to-be-assessed video stream, and obtains an assessment result based on a parsing result and the configuration information of the video service transmission system.

Abstract: A video service quality assessment method and apparatus, where a monitoring device is configured to: obtain an identifier of a to-be-monitored channel, an identifier of to-be-monitored user equipment, and configuration information of a video service transmission system; obtain a multicast video stream of the to-be-monitored channel based on the identifier of the to-be-monitored channel; obtain a retransmitted video stream based on the identifier of the to-be-monitored channel, the identifier of the to-be-monitored user equipment, and the configuration information of the video service transmission system; determine a to-be-assessed video stream based on the multicast video stream and the retransmitted video stream; parse the to-be-assessed video stream; and obtain an assessment result based on a parsing result and the configuration information of the video service transmission system.

Abstract: An online system predicts, using a first targeting model, a first group of users as candidates to be in a targeting cluster, and predicts, using a second targeting model, a second group of users as candidates to be in the targeting cluster. The online system determines a first set of users that are not part of the first group of users, and a second set of users that are not part of the second group of users, and provides surveys to the first and second set of users. The online system determines a first subgroup of the first group of users and a second subgroup of the second group of users, and provides an ad preferences tool to the first subgroup and the second subgroup. The online system scores the first and second targeting models based in part on responses to the surveys and/or the ad preferences tools.

Abstract: This application discloses a data transmission method, a sending device, a receiving device, and a communications system. The sending device is configured to send a first transport block. The sending device obtains a coded bit segment from a first encoded code block. The first encoded code block is obtained after LDPC encoding is performed on a first code block in the first transport block based on a processing capability of the receiving device. The sending device sends the coded bit segment to the receiving device. Because the processing capability of the receiving device is considered, storage overheads of the sending device or the receiving device can be reduced, encoding or decoding complexity can be reduced, and a decoding success rate can be improved.

Abstract: A method and an apparatus for detecting a scene change frame in a video and a system, where when a scene change frame in the video is detected, whether a maximum P frame (Pmax) in all P frames in a group of pictures (GOP) of the video is a scene change frame is determined based on a relative relationship between a size Pkmax of Pmax and a median or an average of sizes of a plurality of I frames between Pmax and a scene change frame closest to Pmax and before Pmax, or a relative relationship between Pkmax and a median or an average of sizes of a plurality of P frames in the GOP to detect a scene change frame in the P frames such that missed detection of a scene change frame is effectively reduced.

Abstract: The present invention discloses a method, an apparatus, and a system for implementing video quality assessment. When video quality is assessed, a proportion of a damaged data caused by packet loss in a video frame in which the damaged data is located is considered, and other factors are also considered, such as a position of the damaged data in the video frame and impact of a scene in which the video frame is located on the video frame or a video frame located after the video frame. Therefore, accuracy of quality assessment is higher.

Abstract: A method for preparing an ultrathin two-dimensional (2D) monocrystalline nanosheet, the method including: 1) placing BiX3 powder where X=I, Br, or Cl in a crucible, and putting the crucible on a first heating zone of a furnace disposed at a gas inlet of a quartz tube; placing substrates covered with metal sheets on a second heating zone of the furnace disposed at a gas outlet of the quartz tube; 2) vacuumizing the quartz tube; pumping Ar gas into the quartz tube until the air pressure is 101.325 kPa; pumping a carrier gas into the quartz tube; and 3) heating and maintaining the second heating zone; heating the first heating zone for BiX3 evaporation until producing chemical reaction between BiX3 and the metal sheets, and preparing ultrathin 2D nanosheets on the substrates simultaneously; and cooling the substrate naturally to 15-30° C.

Abstract: A video quality assessment method includes obtaining a video quality assessment parameter of a to-be-assessed video, where the video quality assessment parameter of the to-be-assessed video includes an average packet loss gap of the to-be-assessed video, determining packet loss dispersion of the to-be-assessed video based on the video quality assessment parameter of the to-be-assessed video, and determining quality of the to-be-assessed video based on a packet loss rate of the to-be-assessed video, an average consecutive packet loss length of the to-be-assessed video, the packet loss dispersion of the to-be-assessed video, and attribute information of the to-be-assessed video. Therefore, during video quality assessment, impact of packet loss distribution indicated by the packet loss dispersion on the video quality is considered.

Abstract: A hot live video determining method is provided. A network device first obtains a plurality of video request messages for a target video; then determines statistical information of the target video based on the plurality of video request messages, where the statistical information includes a quantity of video request messages for the target video that are obtained in specified duration and fragment information of a video fragment requested in each video request message; and finally determines, based on the statistical information, whether the target video is a hot live video. According to the method, the network device can identify the hot live video in the Internet, so the network device can carry the hot live video in a multicast manner, to avoid breakdown that is of a network and a video server and that is caused by transmitting the hot live video in a unicast method.

Abstract: When video quality is assessed, a proportion of a damaged data caused by packet loss in a video frame in which the damaged data is located is considered, and other factors are also considered, such as a position of the damaged data in the video frame and impact of a scene in which the video frame is located on the video frame or a video frame located after the video frame. Therefore, accuracy of quality assessment is higher.