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LVC (Layered video coding)

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Introduction

Layered Video Coding (LVC) is a coding technique that allows a video stream to be divided into multiple layers with different quality and spatial resolution. LVC provides a flexible framework for scalable video coding that enables efficient transmission and storage of video data over heterogeneous networks and devices. The basic idea behind LVC is to divide a video into several layers, with each layer containing a part of the video data that can be decoded independently. In this way, a decoder can choose to decode only the layers that are necessary to display the video at a particular quality level, depending on the available resources and network conditions.

Background

The goal of video compression is to reduce the amount of data needed to represent a video signal while maintaining an acceptable level of quality. Video compression techniques typically exploit the spatial and temporal redundancies in the video data to achieve this goal. Spatial redundancy refers to the fact that adjacent pixels in a frame are often highly correlated, while temporal redundancy refers to the fact that adjacent frames in a video are often highly similar. Video compression standards such as H.264/AVC, HEVC, and AV1 use a variety of techniques to exploit these redundancies, including intra-frame prediction, inter-frame prediction, transform coding, and entropy coding.

Scalable video coding is a coding technique that allows a video to be encoded into multiple layers with different spatial resolution and quality levels. Scalable video coding enables efficient transmission and storage of video data over heterogeneous networks and devices, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level. Scalable video coding is typically achieved using spatial, temporal, or quality scalability.

Spatial scalability involves encoding a video into multiple layers with different spatial resolutions, such as different levels of down-sampling or sub-sampling. Temporal scalability involves encoding a video into multiple layers with different temporal resolutions, such as different frame rates or key-frame intervals. Quality scalability involves encoding a video into multiple layers with different quality levels, such as different levels of quantization or filtering.

Layered video coding is a specific form of scalable video coding that involves dividing a video into multiple layers with different spatial resolutions and quality levels. LVC enables efficient transmission and storage of video data over heterogeneous networks and devices, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.

Overview of Layered Video Coding

Layered video coding involves dividing a video into multiple layers with different spatial resolutions and quality levels. Each layer is encoded independently using a scalable video coding technique, such as H.264/AVC or HEVC. The layers are then transmitted or stored separately, allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.

The layers in an LVC stream are typically organized into a hierarchical structure, with each layer representing a different level of spatial resolution or quality. The lowest layer in the hierarchy contains the highest spatial resolution and the highest quality, while each subsequent layer represents a lower spatial resolution or lower quality. The highest layer in the hierarchy contains the lowest spatial resolution and the lowest quality.

Each layer in an LVC stream is typically encoded using a scalable video coding technique, such as H.264/AVC or HEVC. Scalable video coding enables efficient transmission and storage of video data over heterogeneous networks and devices, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.

Scalable video coding typically involves encoding a video into multiple layers with different spatial resolution, temporal resolution, or quality levels. Spatial scalability involves encoding a video into multiple layers with different spatial resolutions, such as different levels of down-sampling or sub-sampling. Temporal scalability involves encoding a video into multiple layers with different temporal resolutions, such as different frame rates or key-frame intervals. Quality scalability involves encoding a video into multiple layers with different quality levels, such as different levels of quantization or filtering.

In layered video coding, spatial scalability is the most commonly used technique, as it provides the most flexibility in terms of adapting the video quality to the available resources and network conditions. Spatial scalability involves encoding a video into multiple layers with different spatial resolutions, such as different levels of down-sampling or sub-sampling. Each layer is then transmitted or stored separately, allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.

The layers in an LVC stream are typically organized into a hierarchical structure, with each layer representing a different level of spatial resolution or quality. The lowest layer in the hierarchy contains the highest spatial resolution and the highest quality, while each subsequent layer represents a lower spatial resolution or lower quality. The highest layer in the hierarchy contains the lowest spatial resolution and the lowest quality.

The LVC stream is typically transmitted using a streaming protocol such as RTSP, RTP/RTCP, or HTTP. The streaming protocol provides a mechanism for transmitting the different layers of the LVC stream separately, allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.

Benefits of Layered Video Coding

The benefits of layered video coding include:

  1. Scalability: Layered video coding enables efficient transmission and storage of video data over heterogeneous networks and devices, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.
  2. Adaptability: Layered video coding provides a flexible framework for adapting the video quality to the available resources and network conditions, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.
  3. Robustness: Layered video coding provides robustness to network errors and losses, by allowing the decoder to selectively decode only the layers that are available and discarding the layers that are lost or corrupted.
  4. Efficiency: Layered video coding enables efficient compression of video data, by exploiting the spatial and temporal redundancies in the video data and enabling selective decoding of the different layers of the video data.

Applications of Layered Video Coding

Layered video coding has applications in a variety of domains, including:

  1. Video conferencing: Layered video coding enables efficient transmission of video data over heterogeneous networks and devices, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.
  2. Mobile video: Layered video coding enables efficient transmission and storage of video data on mobile devices, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level.
  3. Streaming video: Layered video coding enables efficient streaming of video data over the Internet, by enabling selective decoding of the different layers of the video data and adapting the video quality to the available resources and network conditions.
  4. Video surveillance: Layered video coding enables efficient transmission and storage of video data in video surveillance systems, by enabling selective decoding of the different layers of the video data and adapting the video quality to the available resources and network conditions.

Conclusion

Layered Video Coding is a scalable video coding technique that enables efficient transmission and storage of video data over heterogeneous networks and devices. LVC provides a flexible framework for adapting the video quality to the available resources and network conditions, by allowing the decoder to selectively decode only the layers that are necessary to display the video at a particular quality level. LVC is widely used in applications such as video conferencing, mobile video, streaming video, and video surveillance. LVC has many benefits, including scalability, adaptability, robustness