data-compression | 易学教程

Programmatically add AVI file header to video stream

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问题 I have a capturing device (analogue to digital converter: AverMedia USB Capture Card). When I want to record video using DirectShowLib in C#, I only receive frames. I am able to record frames and play the file using RawVideo Player. How can I create a standard video file header like AVI? Second problem occurs when I want to compress the data. When I use compression, I can't read it at all. Here is my working GraphEdit schema: How can I create standard AVI or MPEG file with header and etc? 回答1

Node.js Compression Proxy for Data saving

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问题 I am looking for a Proxy Server in Node.js which compresses the data I receive through internet similar to Google's Data Saver extension. I want the server to compress the data of every process in my computer which uses internet. I am asking this because I want to reduce my Data usage so that I can reduce my costs for Internet. I don't know whether it is possible or not. Google's Data Saver only compresses http requests. I want the server to compress https as well. So basically if I request a

Ho to setup and use the LZMA compression algorithm SDK

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问题 Making some research on the net, I found that one of the most recent, optimized and high-performance algorithms for data compression, especially in term of compression ratio and decompression time is the LZMA Algorithm. It's supported in many popular software like WinRAR, WinZip, and 7-Zip (By default). I have found the LZMA SDK here http://www.7-zip.org/sdk.html But i haven't found a way to install it in windows or to use the source code provided (examples). For example : In DOC ==> 7cC.txt

How compress data in memory buffer by using libbz2 library in C program

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问题 I try to compress memory data by using libbz2 library in C program. Should I use this function of libbz2?: int BZ2_bzCompress ( bz_stream *strm, int action ); Can anyone show me an example? Thank you. 回答1: http://www.bzip.org/1.0.3/html/util-fns.html Use BZ2_bzBuffToBuffCompress() and BZ2_bzBuffToBuffDecompress() for simple paired compress/decompress. This page describes the meaning of the last 3 parms: http://www.bzip.org/1.0.3/html/low-level.html 来源： https://stackoverflow.com/questions

What is the computer science definition of entropy?

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问题 I've recently started a course on data compression at my university. However, I find the use of the term "entropy" as it applies to computer science rather ambiguous. As far as I can tell, it roughly translates to the "randomness" of a system or structure. What is the proper definition of computer science "entropy"? 回答1: Entropy can mean different things: Computing In computing, entropy is the randomness collected by an operating system or application for use in cryptography or other uses

What is the computer science definition of entropy?

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I've recently started a course on data compression at my university. However, I find the use of the term "entropy" as it applies to computer science rather ambiguous. As far as I can tell, it roughly translates to the "randomness" of a system or structure. What is the proper definition of computer science "entropy"? Entropy can mean different things: Computing In computing, entropy is the randomness collected by an operating system or application for use in cryptography or other uses that require random data. This randomness is often collected from hardware sources, either pre-existing ones

How to reduce a bigger string in smaller string in C++? Probably by hashing?

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I want to compress a bigger string into a smaller string in C++. What are the different ways to do this in C++? The requirement is that output should also be a string. Well, if you don't need to uncompress it later: string s = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"; s = ""; Edit: Sounds like you want a hash function - there are a zillion out there, depending on your requirements. Google is your friend. As unaperson said, Google is your friend: Data Compression Algorithms . Here are a few off the top of my head: RLE -- Run Length encoded Huffman Lepel-Ziv As I understand from comments of

How compress data in memory buffer by using libbz2 library in C program

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I try to compress memory data by using libbz2 library in C program. Should I use this function of libbz2?: int BZ2_bzCompress ( bz_stream *strm, int action ); Can anyone show me an example? Thank you. http://www.bzip.org/1.0.3/html/util-fns.html Use BZ2_bzBuffToBuffCompress() and BZ2_bzBuffToBuffDecompress() for simple paired compress/decompress. This page describes the meaning of the last 3 parms: http://www.bzip.org/1.0.3/html/low-level.html 来源： https://stackoverflow.com/questions/9577735/how-compress-data-in-memory-buffer-by-using-libbz2-library-in-c-program

How to reduce a bigger string in smaller string in C++? Probably by hashing?

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问题 I want to compress a bigger string into a smaller string in C++. What are the different ways to do this in C++? The requirement is that output should also be a string. 回答1: Well, if you don't need to uncompress it later: string s = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"; s = ""; Edit: Sounds like you want a hash function - there are a zillion out there, depending on your requirements. Google is your friend. 回答2: As unaperson said, Google is your friend: Data Compression Algorithms. Here are a

Any theoretical limit to compression?

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Imagine that you had all the supercomputers in the world at your disposal for the next 10 years. Your task was to compress 10 full-length movies losslessly as much as possible. Another criteria was that a normal computer should be able to decompress it on the fly and should not need to spend much of his HD to install the decompressing software. My question is, how much more compression could you achieve than the best alternatives today? 1%, 5%, 50%? More specifically: is there a theoretical limit to compression, given a fixed dictionary size (if it is called that for video compression as well)