4 research outputs found
Modified inter prediction H.264 video encoding for maritime surveillance
Video compression has evolved since it is first being standardized. The most popular CODEC, H.264 can compress video effectively according to the quality that is required. This is due to the motion estimation (ME) process that has impressive features like variable block sizes varying from 4×4 to 16×16 and quarter pixel motion compensation. However, the disadvantage of H.264 is that, it is very complex and impractical for hardware implementation. Many efforts have been made to produce low complexity encoding by compromising on the bitrate and decoded quality. Two notable methods are Fast Search Mode and Early Termination. In Early Termination concept, the encoder does not have to perform ME on every macroblock for every block size. If certain criteria are reached, the process could be terminated and the Mode Decision could select the best block size much faster. This project proposes on using background subtraction to maximize the Early Termination process. When recording using static camera, the background remains the same for a long period of time where most macroblocks will produce minimum residual. Thus in this thesis, the ME process for the background macroblock is terminated much earlier using the maximum 16×16 macroblock size. The accuracy of the background segmentation for maritime surveillance video case study is 88.43% and the true foreground rate is at 41.74%. The proposed encoder manages to reduce 73.5% of the encoding time and 80.5% of the encoder complexity. The bitrate of the output is also reduced, in the range of 20%, compared to the H.264 baseline encoder. The results show that the proposed method achieves the objectives of improving the compression rate and the encoding time
Efficient compression of synthetic video
Streaming of on-line gaming video is a challenging problem because of the enormous
amounts of video data that need to be sent during game playing, especially within the
limitations of uplink capabilities. The encoding complexity is also a challenge because of
the time delay while on-line gamers are communicating.
The main goal of this research study is to propose an enhanced on-line game video
streaming system. First, the most common video coding techniques have been evaluated.
The evaluation study considers objective and subjective metrics. Three widespread video
coding techniques are selected and evaluated in the study; H.264, MPEG-4 Visual and VP-
8. Diverse types of video sequences were used with different frame rates and resolutions.
The effects of changing frame rate and resolution on compression efficiency and viewers‟
satisfaction are also presented. Results showed that the compression process and perceptual
satisfaction are severely affected by the nature of the compressed sequence. As a result,
H.264 showed higher compression efficiency for synthetic sequences and outperformed
other codecs in the subjective evaluation tests.
Second, a fast inter prediction technique to speed up the encoding process of H.264 has
been devised. The on-line game streaming service is a real time application, thus,
compression complexity significantly affects the whole process of on-line streaming. H.264
has been recommended for synthetic video coding by our results gained in codecs
comparative studies. However, it still suffers from high encoding complexity; thus a low
complexity coding algorithm is presented as fast inter coding model with reference
management technique. The proposed algorithm was compared to a state of the art method,
the results showing better achievement in time and bit rate reduction with negligible loss of
fidelity.
Third, recommendations on tradeoff between frame rates and resolution within given uplink
capabilities are provided for H.264 video coding. The recommended tradeoffs are offered as a result of extensive experiments using Double Stimulus Impairment Scale (DSIS)
subjective evaluation metric. Experiments showed that viewers‟ satisfaction is profoundly
affected by varying frame rates and resolutions. In addition, increasing frame rate or frame
resolution does not always guarantee improved increments of perceptual quality. As a
result, tradeoffs are recommended to compromise between frame rate and resolution within
a given bit rate to guarantee the highest user satisfaction.
For system completeness and to facilitate the implementation of the proposed techniques,
an efficient game video streaming management system is proposed.
Compared to existing on-line live video service systems for games, the proposed system
provides improved coding efficiency, complexity reduction and better user satisfaction