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To fulfill these requirements, it is beneficial that video is simultaneously transmitted or stored with a variety of spatial or temporal resolutions or qualities which is the purpose of video bit-stream scalability. The need for scalability arises from graceful degradation transmission requirements, or adaptation needs for spatial formats, bit rates or power.
#Avc video codec 720p
720p or 1080i), while more advanced hardware will be able decode high quality video stream ( 1080p).īit-stream scalability for video is a desirable feature for many multimedia applications. SVC enables forward compatibility for older hardware: the same bitstream can be consumed by basic hardware which can only decode a low-resolution subset (i.e. Combined scalability: a combination of the 3 scalability modalities described above.
#Avc video codec code
The data and decoded samples of lower qualities can be used to predict data or samples of higher qualities in order to reduce the bit rate to code the higher qualities. SNR/Quality/Fidelity scalability: video is coded at a single spatial resolution but at different qualities.The data and decoded samples of lower resolutions can be used to predict data or samples of higher resolutions in order to reduce the bit rate to code the higher resolutions. Spatial (picture size) scalability: video is coded at multiple spatial resolutions.SVC has only provided supplemental enhancement information to improve its usage. Temporal scalability is already enabled by H.264/MPEG-4 AVC (also it's available in some other formats, such that VP8 ). their associated packets) can be dropped from the bitstream.
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The subset bitstream is derived by dropping packets from the larger bitstream.Ī subset bitstream can represent a lower spatial resolution (smaller screen), or a lower temporal resolution (lower frame rate), or a lower quality video signal (each separately or in combination) compared to the bitstream it is derived from. Master of Science (M.S.The objective of the SVC standardization has been to enable the encoding of a high-quality video bitstream that contains one or more subset bitstreams that can themselves be decoded with a complexity and reconstruction quality similar to that achieved using the existing H.264/MPEG-4 AVC design with the same quantity of data as in the subset bitstream. These studies helped us in understanding which codec can be more robust against channel errors or losses and how we can improve their performance. In addition, we have analyzed the creation of different priorities based on cumulative mean squared error (CMSE) values for dividing the I, P and B video frames into four priorities. Observations based on the PSNR values and rate-control have been used to analyze the objective video quality for error-free and corrupted bitstreams generated by both codecs.
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We have studied various features of these codecs, such as macroblock tree rate control, multi-pass encoding, and psychovisual optimization model (it includes the parameters like adaptive quantization, psy-RD and psy-trellis). In this thesis, we have studied the comparative performance of two prominent open source H.264 AVC video codecs - Joint Model (JM) and Fast Forward Motion Picture Expert Group (FFMPEG). Hence, a video codec needs to accommodate contradictory requirements: coding efficiency and robustness to data loss, along with other limitations such as memory, bandwidth, real time coding and complexity. The perceptual video quality is influenced not only by the compression artifacts, but also by the channel errors. This has led to the design of error resiliency schemes for obtaining better codecs. With the rapid growth of wireless multimedia services, the demand for video transmission over wireless channels has been increasingly exponentially. Comparative performance of JM and FFMPEG codecs of H.264 AVC video compression standard