| This article firstly introduced the news exchange business between domestic TV stations and the existing problems in the business. It then analyzed the technical situation of domestic video-audio exchange websites and the video websites, and thus proposed the design and implementation of an internet-based news exchange platform. On this platform, the news exchange and cooperation between TV stations can be realized through the functions such as video transmission, rough editing and cutting-jointing of video files, video code transformation, and information publishing, etc.Based on studies done, to ensure broadcasting quality, most domestic TV stations use the MPEG-2 coding standard to code the video files. However, the obtained file size is relatively large. Therefore, in order to realize news cooperation between different TV stations and build the internet-based news exchange platform, the key technical issue is to smoothly transmit the large volume of MPEG-2 video-audio data in a low bandwidth situation. This article discussed the business process of the news exchange between domestic TV stations, and thus proposed a solution that greatly improve the video transmission efficiency by optimizing the video uploading, editing, and downloading process and technologiesFirst of all, in the video uploading process, the author suggested that the news provider should upload the programme list so that the news receiver can decided what to download from the listed news materials. After that the news provider will upload the video files that have been selected by the receiver. This can decrease and release the space and bandwidth occupied from unnecessarily uploaded files without a good understanding of the customer's needs.In the video downloading process, the author suggested to advance the video-audio rough editing work. To be more specific, it significantly reduces the size of the video-audio files to be downloaded by cutting and jointing technologies, and thus improving the downloading efficiency of the files. However, in order to do the internet-based rough editing in a low bandwidth condition, it is suggested that the video-audio sequences should be read from the high bit rate news video files, and be made into an index table of the news video files. After that, the news receiver/user will produce an index table of the video sequences that are to be downloaded by dotting the low bit rate video files. The downloading client end will then download the corresponding video sequences of the high bit rate video files according to the video sequence index table, and put them together into a video file that can be smoothly played. It solves the bottle neck problem of the bandwidth by dotting the low bit rate video files on the news exchange platform and putting together the high bit rate video sequences downloaded at the client end. Meanwhile the index table of the high bit rate video files generated on the news exchange platform will replace the many cut parts of video files and thus release the saving space needed.Lastly, to speed up the downloading, the author chose to implement the downloading by combining the BitTorrent protocol based P2P data transmission technology with the MPEG-2 video file editing technology, given the video index table can be easily transformed to torrents in the BitTorrent protocol. It was the case that only a complete file can be downloaded under the BitTorrent protocol. But now by converting the file format and information exchange among torrents, the partible video sequences can be downloaded according to the video index table. Meanwhile the time stamp of the downloaded data will be updated, so as to realize the assembling of the video file and a smooth play of it. |
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