用C语言对给定的一维数组进行压缩,编写DPCM有损数据压缩算法,包含(一阶线性预测,设定量化步长对预测误差量化,对量化的误差进行算数编码得到压缩的数据,对压缩数据用算术解码器解码,然后反量化误差,加上预测值,得到解压缩后的数据)的程序
时间: 2023-06-19 14:05:48 浏览: 99
压缩算法,C语言编写的
下面是一份简单的DPCM有损数据压缩算法的C语言实现。它实现了一阶线性预测、设定量化步长、算术编码和算术解码器,并在压缩和解压缩时进行反量化误差和加上预测值,以得到解压缩的数据。
```c
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
// 宏定义一些常量
#define N 1000 // 数组大小
#define QUANTIZATION_STEP 8 // 量化步长
// 一阶线性预测,返回预测值
int linearPredict(int prev, int cur) {
return prev + (cur - prev) / 2;
}
// 将一个整数转为二进制表示的字符串,用于算术编码
char *intToBinaryString(int n) {
char *str = (char*)malloc(33);
str[32] = '\0';
int i;
for (i = 0; i < 32; i++) {
str[31 - i] = (n & (1 << i)) ? '1' : '0';
}
return str;
}
// 算术编码
void arithmeticEncode(int *data, int size) {
int low = 0, high = 0xffffffff;
int range = high - low + 1;
int i;
for (i = 0; i < size; i++) {
int x = data[i];
int pred = (i == 0) ? 0 : data[i - 1];
int error = x - linearPredict(pred, x);
int quantized = error / QUANTIZATION_STEP;
int qerror = quantized * QUANTIZATION_STEP;
int symbol = quantized + 128;
int cum_freq = symbol - 128;
int freq = 255;
int lrange = low + range * cum_freq / freq;
int hrange = low + range * (cum_freq + 1) / freq - 1;
low = lrange;
high = hrange;
while (1) {
if ((low >> 31) == (high >> 31)) {
putchar(low >> 31);
while (x > 0) {
putchar(!(low >> 31));
x--;
}
break;
} else if ((low & 0x7fffffff) >= 0x40000000 && (high & 0x7fffffff) < 0x40000000) {
x++;
low &= 0x3fffffff;
high |= 0x40000000;
} else {
break;
}
low <<= 1;
high <<= 1;
high |= 1;
}
range = high - low + 1;
}
putchar(low >> 24);
putchar((low >> 16) & 0xff);
putchar((low >> 8) & 0xff);
putchar(low & 0xff);
}
// 从二进制表示的字符串中读取一个整数,用于算术解码
int binaryStringToInt(char *str) {
int n = 0, i;
for (i = 0; i < 32; i++) {
n |= ((str[31 - i] - '0') << i);
}
return n;
}
// 算术解码器
int arithmeticDecode(int *output, int size) {
int low = 0, high = 0xffffffff;
int range = high - low + 1;
int i;
for (i = 0; i < size; i++) {
int cum_freq = 0;
int freq = 255;
while (1) {
int lrange = low + range * cum_freq / freq;
int hrange = low + range * (cum_freq + 1) / freq - 1;
if ((low >> 31) == (high >> 31)) {
break;
} else if ((low & 0x7fffffff) >= 0x40000000 && (high & 0x7fffffff) < 0x40000000) {
cum_freq = (cum_freq << 1) + ((output[i] == 1) ? 1 : 0);
low &= 0x3fffffff;
high |= 0x40000000;
} else if ((low & 0x40000000) && !(high & 0x40000000)) {
cum_freq = (cum_freq << 1) + 1;
low &= 0x3fffffff;
high |= 0x40000000;
} else {
break;
}
low <<= 1;
high <<= 1;
high |= 1;
}
int symbol = cum_freq + 128;
int quantized = symbol - 128;
int error = quantized * QUANTIZATION_STEP;
int pred = (i == 0) ? 0 : output[i - 1];
int x = linearPredict(pred, output[i]) + error;
output[i] = x;
int lrange = low + range * cum_freq / freq;
int hrange = low + range * (cum_freq + 1) / freq - 1;
low = lrange;
high = hrange;
range = high - low + 1;
}
return output[size - 1];
}
int main(void) {
int data[N];
int i;
for (i = 0; i < N; i++) {
data[i] = rand() % 256;
}
printf("Original data:\n");
for (i = 0; i < N; i++) {
printf("%d ", data[i]);
}
putchar('\n');
arithmeticEncode(data, N);
putchar('\n');
int decoded[N];
int last = arithmeticDecode(decoded, N);
printf("Decoded data:\n");
for (i = 0; i < N; i++) {
printf("%d ", decoded[i]);
}
putchar('\n');
if (last != data[N - 1]) {
printf("Error: last value %d does not match original value %d\n", last, data[N - 1]);
}
return 0;
}
```
这份代码生成了一个长度为N的随机整数数组,并对其进行DPCM压缩和解压缩。可以根据需要修改数组大小和量化步长。注意,这份代码中的算术编码和算术解码器是非常简单的实现,可能不适用于实际应用,因此需要进行适当的改进和优化。
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