Thursday, November 25, 2004

Pattern in streaming video data?

Is there a pattern in streaming video data? I was thinking something along the data in the "magic (5)" file that is automagically used by "file (1)" command. (What a convoluted sentence!) Or something like uuencoded-type pattern?

I am writing a fiction in which the main character was looking at a stream of data. He then recognized that the data is some kind of video stream. Now, what kind of pattern did he see? Is this realistic? He might be looking in the middle of the stream, though. So if the pattern is at the begining of the file, then he might miss it.

2 comments:

andika said...

Mestinya sih begitu. Beberapa format video menempatkan frame kunci pada selang tertentu. Dengan demikian, ketika kita out-of-sync (misal karena ada frame yang drop di tengah), resync dilakukan dengan mencari key frame tadi, lalu frame-frame berikutnya yang berisi delta dibangun berdasarkan key frame tsb.
Lalu kalau videonya disertai suara, akan ada minimal dua stream, time-sharing. Mestinya ada pembatas yang jelas, mana penggalan gambar, dan mana penggalan suara.

Anonymous said...

Bisa jadi; umumnya, video data stream tersusun atas GOP (group of picture) yg memiliki pattern tertentu. Ini tergantung dari encoding yg dipakai oleh format video ybs. It also depends on the allocated bit-rate to encode the video. In general, there are three types of pictures used in a GOP: I-picture, P-picture, and B-picture; they all have different characteristics, uniquely atributed to each one of them. So, it is possible that one might recognize a pattern when looking at a stream of data.