MPEG算法及代码例程-CFANZ编程社区

MPEG算法及代码例程

MPEG（Moving Picture Experts Group）是一组视频压缩算法标准，用于对视频进行压缩和编码。MPEG算法的主要目标是在保持较高视频质量的同时，实现较高的压缩比。

MPEG算法涉及多个阶段，包括空域预处理、变换编码、运动估计与补偿、熵编码等。下面是MPEG算法的主要步骤：

以上是MPEG算法的基本步骤，实际的MPEG标准包含许多细节和参数设置，如GOP结构、码率控制、渐进传输等。具体的MPEG算法和参数会根据不同的标准（如MPEG-1、MPEG-2、MPEG-4等）而有所区别。

下面是一个简单的MPEG压缩算法的代码例程：

import cv2 import numpy as np

def compress_frames(frames): compressed_frames = []

for frame in frames:
    # 转换为YUV颜色空间
    yuv_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2YUV)
    
    # 分割成8x8块
    blocks = [yuv_frame[j:j+8, i:i+8] for j in range(0, yuv_frame.shape[0], 8) 
              for i in range(0, yuv_frame.shape[1], 8)]
    
    compressed_blocks = []
    
    for block in blocks:
        # 应用离散余弦变换（DCT）
        dct_block = cv2.dct(np.float32(block))
        
        # 量化
        quantized_block = np.round(dct_block / quantization_matrix)
        
        compressed_blocks.append(quantized_block)
    
    compressed_frames.append(compressed_blocks)

return compressed_frames

def decompress_frames(compressed_frames): decompressed_frames = []

for frame in compressed_frames:
    decompressed_blocks = []
    
    for block in frame:
        # 反量化
        quantized_block = block * quantization_matrix
        
        # 反DCT变换
        idct_block = cv2.idct(np.float32(quantized_block))
        
        decompressed_blocks.append(idct_block)
    
    # 合并块
    yuv_frame = np.vstack([np.hstack(decompressed_blocks[i:i+int(yuv_frame.shape[1]/8)]) 
                           for i in range(0, len(decompressed_blocks), int(yuv_frame.shape[1]/8))])
    
    # 转换回RGB颜色空间
    decompressed_frame = cv2.cvtColor(yuv_frame, cv2.COLOR_YUV2BGR)
    
    decompressed_frames.append(decompressed_frame)

return decompressed_frames

假设quantization_matrix是一个8x8的量化矩阵（包含MPEG标准或自定义的值）

quantization_matrix = np.array([...])

加载视频

video = cv2.VideoCapture('input.mp4')

frames = [] while True: ret, frame = video.read() if not ret: break frames.append(frame)

压缩视频帧

compressed_frames = compress_frames(frames)

解压缩视频帧

decompressed_frames = decompress_frames(compressed_frames)

保存解压缩后的视频

output_video = cv2.VideoWriter('output.mp4', cv2.VideoWriter_fourcc(*'mp4v'), 30.0, (640, 480)) for frame in decompressed_frames: output_video.write(frame) output_video.release()

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