Abstract: Techniques for dynamically changing characteristics of simulcast video streams in real-time multi-party video conferences. Once a video conference has been established for a plurality of participant devices, each participant device can provide a notification of its supported video communications characteristic(s) for sending simulcast video streams and receiving video streams. Having been provided such notification, the media server can determine video communications setting(s) and/or parameter(s) to be used by each participant device while sending simulcast video streams or receiving video streams based on the supported video communications characteristic(s) of the respective participant devices.

Abstract: Techniques for dynamically changing characteristics of simulcast video streams in real-time multi-party video conferences. Once a video conference has been established for a plurality of participant devices, each participant device can provide a notification of its supported video communications characteristic(s) for sending simulcast video streams and receiving video streams. Having been provided such notification, the media server can determine video communications setting(s) and/or parameter(s) to be used by each participant device while sending simulcast video streams or receiving video streams based on the supported video communications characteristic(s) of the respective participant devices.

Abstract: Techniques for providing selective video forwarding in real-time video applications involving multiple user devices. The techniques can be employed in WebRTC videoconferences, taking into account the heterogeneous natures of device display resolutions and networks in which the respective devices operate. The techniques employ a selective forwarding unit (SFU) having a real-time adaptive video transcoder. The SFU determines whether a benefit to quality of experience (QoE) can be achieved by performing, in real-time, adaptive video transcoding on large video streams produced by the respective devices. If a heterogeneity value associated with available network bandwidths is greater than a predetermined value and sufficient CPU/memory resources are available, then the real-time adaptive video transcoder performs, in real-time, adaptive video transcoding on the large video streams to produce corresponding small video streams, which are selectively forwarded to user devices having low available network bandwidths.

Abstract: Techniques for dynamically changing characteristics of simulcast video streams in real-time multi-party video conferences. Once a video conference has been established for a plurality of participant devices, each participant device can provide a notification of its supported video communications characteristic(s) for sending simulcast video streams and receiving video streams. Having been provided such notification, the media server can determine video communications setting(s) and/or parameter(s) to be used by each participant device while sending simulcast video streams or receiving video streams based on the supported video communications characteristic(s) of the respective participant devices.

Abstract: Systems and methods of media servers for estimating the video quality of experience (QoE) of human viewers of video content or communications at video receivers. With these systems and methods, a media server can collect, within a plurality of predetermined time windows synchronized in time, operational parameters of ingress and egress networks over which such video content or communications can be transmitted, as well as coding parameters of a video decoder and a video encoder within the media server. Having collected the operational parameters of the ingress network and egress network and the coding parameters of the video decoder and video encoder, the media server can determine QoE scores associated with some or all the ingress network, the video decoder, the video encoder, and the egress network, and estimate a resulting video QoE for a human viewer at a video receiver as a predefined combination of the respective QoE scores.

Abstract: Techniques for handling sudden changes in available bandwidth in videoconferences implemented with media servers employing SFUs. The techniques involve detecting a sudden drop in available egress network bandwidth from a media server to a video receiver, sending a request to a video sender currently sending a video stream to the media server for forwarding to the video receiver to reduce its transmission bitrate, determining whether to reset the forwarding of the video stream to the video receiver, and, having determined to reset the forwarding of the video stream to the video receiver, stopping the forwarding of the video stream to the video receiver, sending a request for an I-frame to the video sender for use in restarting the forwarding of the video stream to the video receiver, and, having received the requested I-frame, restarting the forwarding of the video stream from the video sender to the video receiver.

Abstract: Techniques for handling sudden changes in available bandwidth in videoconferences implemented with media servers employing SFUs. The techniques involve detecting a sudden drop in available egress network bandwidth from a media server to a video receiver, sending a request to a video sender currently sending a video stream to the media server for forwarding to the video receiver to reduce its transmission bitrate, determining whether to reset the forwarding of the video stream to the video receiver, and, having determined to reset the forwarding of the video stream to the video receiver, stopping the forwarding of the video stream to the video receiver, sending a request for an I-frame to the video sender for use in restarting the forwarding of the video stream to the video receiver, and, having received the requested I-frame, restarting the forwarding of the video stream from the video sender to the video receiver.

Abstract: Improved systems and methods of video decoding and recording in real-time video communications for use in lossy network environments. The disclosed systems and methods can employ a plurality of wait time thresholds for retransmission of missing video packets, based at least on the processing performed on the respective video packets, such processing including video decoding in a real-time video communication between client devices, and video recording and storing in a video file. The disclosed system and methods can also adaptively perform error concealment on video frames in the bitstream domain prior to recording and storing encoded video frame data in a video file, based at least on estimates of the complexities of the respective video frames.

Abstract: Improved systems and methods of video decoding and recording in real-time video communications for use in lossy network environments. The disclosed systems and methods can employ a plurality of wait time thresholds for retransmission of missing video packets, based at least on the processing performed on the respective video packets, such processing including video decoding in a real-time video communication between client devices, and video recording and storing in a video file. The disclosed system and methods can also adaptively perform error concealment on video frames in the bitstream domain prior to recording and storing encoded video frame data in a video file, based at least on estimates of the complexities of the respective video frames.

Abstract: Techniques for handling sudden changes in available bandwidth in videoconferences implemented with media servers employing SFUs. The techniques involve detecting a sudden drop in available egress network bandwidth from a media server to a video receiver, sending a request to a video sender currently sending a video stream to the media server for forwarding to the video receiver to reduce its transmission bitrate, determining whether to reset the forwarding of the video stream to the video receiver, and, having determined to reset the forwarding of the video stream to the video receiver, stopping the forwarding of the video stream to the video receiver, sending a request for an I-frame to the video sender for use in restarting the forwarding of the video stream to the video receiver, and, having received the requested I-frame, restarting the forwarding of the video stream from the video sender to the video receiver.

Abstract: Techniques for providing selective video forwarding in real-time video applications involving multiple user devices. The techniques can be employed in WebRTC videoconferences, taking into account the heterogeneous natures of device display resolutions and networks in which the respective devices operate. The techniques employ a selective forwarding unit (SFU) having a real-time adaptive video transcoder. The SFU determines whether a benefit to quality of experience (QoE) can be achieved by perfonning, in real-time, adaptive video transcoding on large video streams produced by the respective devices. If a heterogeneity value associated with available network bandwidths is greater than a predetermined value and sufficient CPU/memory resources are available, then the real-time adaptive video transcoder performs, in real-time, adaptive video transcoding on the large video streams to produce corresponding small video streams, which are selectively forwarded to user devices having low available network bandwidths.

Abstract: Improved systems and methods of performing multimedia communications over multimedia communications networks, in which video data senders can maintain high video quality of experience (QoE) levels with increased reliability despite changes in available bandwidths of video data receivers. In the disclosed systems and methods, video encoding parameters employed by the video data senders, including at least the video frame size and/or the video frame rate, can be dynamically adapted to the available bandwidths of the video data receivers, taking into account possible effects of spatial scaling and/or temporal scaling of video frames on the resulting video QoE.

Abstract: Systems, methods, and techniques for providing video forwarding in real-time video applications involving multiple devices. The techniques can be employed in WebRTC videoconferences, taking into account the heterogeneous natures of device display resolutions and networks in which the devices operate. The techniques employ a media server including an SFU having an adaptive video transcoder. The media server determines whether a benefit to QoE is achieved by performing video transcoding on large video streams produced by the respective devices. If a heterogeneity value of available network bandwidths is greater than a predetermined value and CPU/memory resources are available, then the adaptive video transcoder beneficially performs transcoding on the large video streams to produce corresponding small video streams, which are selectively forwarded to devices having low available network bandwidths.

Abstract: Systems and methods of performing intra-frame refresh in multimedia communications over lossy packet networks, in which a video receiver can provide packet loss feedback information to a video transmitter, and the video transmitter can respond to the feedback information, in a manner that makes efficient use of available bandwidth. By providing one or more PLI messages from the video receiver to the video transmitter based on criteria related to the detection of an eventual missing video packet and/or the determination that the quality of a current reference frame is bad, and by pausing the providing of GNACK messages from the video receiver to the video transmitter while the PLI messages are being provided to the video transmitter, the total number of video packets required for transmission/retransmission can be reduced, thereby limiting the impact of the transmitted/retransmitted video packets on the available bandwidth while enhancing the video QoE of system users.

Abstract: Systems and methods of performing rate control in scalable video encoders for use in videoconferencing, announcements, and live video streaming to multiple participant devices having diverse bandwidths, resolutions, and/or other device characteristics. The systems and methods can accommodate different target bit rates of the multiple participant devices by operating on scalable video bitstreams in a multi-layer video format, including a base layer having one or more reference video frames, and an enhancement layer having one or more disposable non-reference, predictive video frames. By adjusting the number of disposable non-reference, predictive video frames in the enhancement layer, as well as quantization parameters for the respective base and enhancement layers, the systems and methods can accommodate the different target bit rates for the respective participant devices, while enhancing the spatial and/or temporal qualities of the base and enhancement layers in the respective video bitstreams.

Abstract: Improved systems and methods of video decoding and recording in real-time video communications for use in lossy network environments. The disclosed systems and methods can employ a plurality of wait time thresholds for retransmission of missing video packets, based at least on the processing performed on the respective video packets, such processing including video decoding in a real-time video communication between client devices, and video recording and storing in a video file. The disclosed system and methods can also adaptively perform error concealment on video frames in the bitstream domain prior to recording and storing encoded video frame data in a video file, based at least on estimates of the complexities of the respective video frames.

Abstract: Improved systems and methods of video decoding and recording in real-time video communications for use in lossy network environments. The disclosed systems and methods can employ a plurality of wait time thresholds for retransmission of missing video packets, based at least on the processing performed on the respective video packets, such processing including video decoding in a real-time video communication between client devices, and video recording and storing in a video file. The disclosed system and methods can also adaptively perform error concealment on video frames in the bitstream domain prior to recording and storing encoded video frame data in a video file, based at least on estimates of the complexities of the respective video frames.

Abstract: Systems and methods of handling packet errors associated with multimedia data received at data receivers from data senders, in which packet error feedback information is provided by the data receivers to the data senders in one or more real-time transport control protocol (RTCP) feedback packets. The data receivers can calculate, determine, or otherwise obtain costs associated with providing specific forms of packet error feedback information in the RTCP feedback packets, and further calculate, determine, or otherwise obtain wait times for handling out-of-order packets, as well as receiving retransmissions of lost packets. By handling packet errors associated with multimedia data while taking into account such costs and wait times, each of which can have an impact on system bandwidth and/or latency, the systems and methods can more reliably achieve the quality of experience (QoE) generally desired and/or required for multimedia data transmissions.

Abstract: Improved systems and methods of video decoding and recording in real-time video communications for use in lossy network environments. The disclosed systems and methods can employ a plurality of wait time thresholds for retransmission of missing video packets, based at least on the processing performed on the respective video packets, such processing including video decoding in a real-time video communication between client devices, and video recording and storing in a video file. The disclosed system and methods can also adaptively perform error concealment on video frames in the bitstream domain prior to recording and storing encoded video frame data in a video file, based at least on estimates of the complexities of the respective video frames.

Abstract: Systems and methods of media servers for estimating the video quality of experience (QoE) of human viewers of video content or communications at video receivers. With these systems and methods, a media server can collect, within a plurality of predetermined time windows synchronized in time, operational parameters of ingress and egress networks over which such video content or communications can be transmitted, as well as coding parameters of a video decoder and a video encoder within the media server. Having collected the operational parameters of the ingress network and egress network and the coding parameters of the video decoder and video encoder, the media server can determine QoE scores associated with some or all the ingress network, the video decoder, the video encoder, and the egress network, and estimate a resulting video QoE for a human viewer at a video receiver as a predefined combination of the respective QoE scores.