The document discusses an interactive media codec algorithm that allows users to control video content in various ways, leveraging MPEG/H.264 compression technologies for efficient bandwidth use. It details the structure of these codecs, emphasizing the differences between temporal and transmission orders of video frames and presents an interactive algorithm for enhanced visual quality. Future work aims to optimize these algorithms for reduced complexity and improved functionality across diverse network types.

1. Networked Interactive Media Codec Algorithm Kostas E. Psannis and Yutaka Ishibashi Department of Technology Management University of Macedonia, Thessaloniki 540 06, Greece [email_address] , [email_address] Department of Computer Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan

2. PRELIMINARY Interactive access to video content is generally defined as a program or service controlled by the user and which can affect the content itself, the presentation manner of the content, or the presentation order of the content Full range of interactive functions include play/resume, stop, pause, Jump Forward (JF)/ Jump Backward (JB), Fast Forward (FF)/ Fast Rewind FR), Slow down (SD), and Slow Reverse (SR), Rewind.

3. Introduction MPEG/H.264 codec Interactive Media Codec Algorithms Proposed Interactive Media Algorithm Experiments Conclusions

4. MPEG/H.264-structure (a) Video Compression technologies have evolved in the series of MPEG-1/2 and MPEG-4/H.264 Given a bandwidth of several hundred kilobits per second, the recent codecs (H.264) can transmit quality video MPEG/H.264-based video compression is based on motion compensated predictive coding with an I-B-P structure.

5. I-frames are coded such that they are independent of any other frames in the sequence; P-frames are coded using motion estimation and each one has a dependency on the preceding I- or P- frame B- frames depends on the two “anchor” frames - the preceding I/P frame and the following I/P frame MPEG-structure (b)

6. MPEG/H.264-structure (c) An MPEG coded video sequence is typically partitioned into small intervals called GoP (Group of Pictures). The video during the normal mode is coded with all I-P-B frames in order to achieve high compression ratios for the transport over the network with minimum bandwidth resources. An example of the temporal ( Display ) and transmission (Decoding) orders of the normal mode is given below:

7. MPEG-structure (d) To enable continuous playback at the Set Top Box (STB), MPEG frames are transmitted over the network according to the decoding order. This is because of the interpolative nature of B-frames. Hence, the decoding (transmission) order of MPEG sequence is different from its temporal (display playback) order.

8. Streaming Interactive Media Algorithms Drop parts of the original video stream - Send only I - P frames - GoP-Skipping - Partial GoPs-skipping Separate Copies of the movie - Skipping row of frames - Alternative special file

9. Proposed Interactive Media Algorithm The encoding pattern is obtained by encoding the original uncompressed video data as follows P(Marionette) in repeating the previous I-frame in the decoder, enhancing the visual quality during the interactive mode Pi(k) frames are coded using motion estimation and each one has a dependency only to the preceding k-th frame

10. Experiments (a) PSNR as a function of frame index for all the interactive media algorithms for the foreman and coastguard video trace.

11. Experiments (b) Snapshots of Coastguard (1) and Foreman (2) video traces for the Alternative Special File method (1,2)a , Send only I- P frames approach (1,2)b and the proposed interactive media codec algorithm (1,2)c. 1a 1c 1b 2a 2c 2b

12. Conclusions- Future Work By proper encoding MPEG/ H.264 media streams, I-P(M)-Pi(k) frames, of the original video sequence, interactive functionality can be supported with considerably reduced network bandwidth and decoder complexity and acceptable visual quality at the clients end Future work involves network simulation of all the algorithms over combined networks from wireline to wireless links.