采集视频后在本地直接进行编码、解码(不进行网传)，为什么显示出来有大量马赛克

最新推荐文章于 2024-08-05 13:11:45 发布

xwchen

最新推荐文章于 2024-08-05 13:11:45 发布

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本文链接：https://blog.youkuaiyun.com/xwchen/article/details/2292244

博主在本地使用VFW API和mpg4c32.dll进行视频编码解码时遇到大量马赛克问题。经过讨论，可能的原因包括：编码解码过程中的错误、解码后数据缓冲区大小不正确、压缩比特率过低、编码后的数据与预期不符。建议检查编解码算法、数据缓冲区大小和比特率设置。

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RT
本人用VFW API写的，编解码库采用微软的mpg4c32.dll，部分代码如下：

//初始化编码
BOOL CSkySunDlg::InitVideoEncoder()
{
m_hicEnc = ICOpen(ICTYPE_VIDEO, m_dwCompressor, ICMODE_FASTCOMPRESS);
if(!m_hicEnc)
{
AfxMessageBox("ICOpen Enc Error!");
return false;
}

m_biEncInput.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
m_biEncInput.bmiHeader.biCompression = BI_RGB;
m_biEncInput.bmiHeader.biWidth = QCIF_WIDTH;
m_biEncInput.bmiHeader.biHeight = QCIF_HEIGHT;
m_biEncInput.bmiHeader.biPlanes = 1;
m_biEncInput.bmiHeader.biBitCount = 24;
m_biEncInput.bmiHeader.biSizeImage = QCIF_WIDTH*QCIF_HEIGHT*1*(24/8);
m_biEncInput.bmiHeader.biXPelsPerMeter = 0;
m_biEncInput.bmiHeader.biYPelsPerMeter = 0;
m_biEncInput.bmiHeader.biClrUsed = 0;
m_biEncInput.bmiHeader.biClrImportant = 0;

m_biEncOutput.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
m_biEncOutput.bmiHeader.biCompression = mmioFOURCC('M','P','4','3');
m_biEncOutput.bmiHeader.biWidth = QCIF_WIDTH;
m_biEncOutput.bmiHeader.biHeight = QCIF_HEIGHT;
m_biEncOutput.bmiHeader.biPlanes = 1;
m_biEncOutput.bmiHeader.biBitCount = 24;
m_biEncOutput.bmiHeader.biSizeImage = QCIF_WIDTH*QCIF_HEIGHT*1*(24/8);
m_biEncOutput.bmiHeader.biXPelsPerMeter = 0;
m_biEncOutput.bmiHeader.biYPelsPerMeter = 0;
m_biEncOutput.bmiHeader.biClrUsed = 0;
m_biEncOutput.bmiHeader.biClrImportant = 0;

if( ICERR_OK != ICCompressBegin(m_hicEnc, &m_biEncInput, &m_biEncOutput) )
{
AfxMessageBox("ICCompressBegin Error!");
return false;
}

return true;
}

//初始化解码
BOOL CSkySunDlg::InitVideoDecoder()
{
m_hicDec = ICOpen(ICTYPE_VIDEO, m_dwCompressor, ICMODE_FASTDECOMPRESS);
if(!m_hicDec)
{
AfxMessageBox("ICOpen Dec error!");
return false;
}

m_biDecInput.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
m_biDecInput.bmiHeader.biCompression = mmioFOURCC('M','P','4','3');
m_biDecInput.bmiHeader.biWidth = QCIF_WIDTH;
m_biDecInput.bmiHeader.biHeight = QCIF_HEIGHT;
m_biDecInput.bmiHeader.biPlanes = 1;
m_biDecInput.bmiHeader.biBitCount = 24;
m_biDecInput.bmiHeader.biSizeImage = QCIF_WIDTH*QCIF_HEIGHT*1*(24/8);
m_biDecInput.bmiHeader.biXPelsPerMeter = 0;
m_biDecInput.bmiHeader.biYPelsPerMeter = 0;
m_biDecInput.bmiHeader.biClrUsed = 0;
m_biDecInput.bmiHeader.biClrImportant = 0;

m_biDecOutput.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
m_biDecOutput.bmiHeader.biCompression = BI_RGB;
m_biDecOutput.bmiHeader.biWidth = QCIF_WIDTH;
m_biDecOutput.bmiHeader.biHeight = QCIF_HEIGHT;
m_biDecOutput.bmiHeader.biPlanes = 1;
m_biDecOutput.bmiHeader.biBitCount = 24;
m_biDecOutput.bmiHeader.biSizeImage = QCIF_WIDTH*QCIF_HEIGHT*1*(24/8);
m_biDecOutput.bmiHeader.biXPelsPerMeter = 0;
m_biDecOutput.bmiHeader.biYPelsPerMeter = 0;
m_biDecOutput.bmiHeader.biClrUsed = 0;
m_biDecOutput.bmiHeader.biClrImportant = 0;

if(ICERR_OK != ICDecompressBegin(m_hicDec, &m_biDecInput, &m_biDecOutput))
{
AfxMessageBox("ICDecompressBegin Error!");
return false;
}

return true;
}

//视频采集
......
capSetCallbackOnVideoStream(m_capWnd,OnVideoStream);//设置回调
......

LRESULT CALLBACK OnVideoStream(HWND mwnd,LPVIDEOHDR lphdr)
{
VideoCapture *vidcap = (VideoCapture *)(capGetUserData(mwnd));

if(vidcap != NULL)
{
((CSkySunDlg *)vidcap->m_pDlg)->ProcessVideo(lphdr->lpData, lphdr->dwBytesUsed);
}

return TRUE;
}

void CSkySunDlg::ProcessVideo(BYTE *pData, int nSize)
{
//显示本地视频(采集到的未经压缩、解压处理的)
::DrawDibDraw(m_hDib, m_hDC, m_localWndX, m_localWndY, -1, -1,
&m_bitmapinfo->bmiHeader, pData, 0, 0, QCIF_WIDTH, QCIF_HEIGHT,
DDF_SAME_DRAW);

//压缩视频
long videosize = QCIF_WIDTH*QCIF_HEIGHT*3;
char OutputBuf[QCIF_WIDTH*QCIF_HEIGHT*3];
memset(OutputBuf, 0, QCIF_WIDTH*QCIF_HEIGHT*3);
DWORD dwFlag;
static long lFrameNum = 0;

DWORD dwResult = ICCompress(m_hicEnc, 0, &m_biEncOutput.bmiHeader, OutputBuf,
&m_biEncInput.bmiHeader, (LPVOID)pData, NULL, &dwFlag, lFrameNum++,
0, 0, NULL, NULL);

int nCompressedSize = m_biEncOutput.bmiHeader.biSizeImage;
if( (dwResult == ICERR_OK) && (nCompressedSize > 0) )
{
//解压视频
char OutputData[512];
memset(OutputData, 0, 512);

DWORD dwRet;
dwRet = ICDecompress(m_hicDec, 0, &m_biDecInput.bmiHeader,
OutputBuf, &m_biDecOutput.bmiHeader, OutputData);
if( ICERR_OK == dwRet )
{
//显示解压后视频
::DrawDibDraw(m_hDib,
m_hDC,
m_remoteWndX,
m_remoteWndY,
-1,
-1,
&m_biDecOutput.bmiHeader,
OutputData,
0,
0,
QCIF_WIDTH,
QCIF_HEIGHT,
DDF_SAME_DRAW
);
}
}
} 问题点数：100、回复次数：10Top

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1 楼ccxian123（力挽狂澜）回复于 2005-07-14 17:02:48 得分 0

先试下不编码直接显示看有没马塞克啊。。Top

2 楼edoch（逸刀客）回复于 2005-07-14 20:01:19 得分 0

不编码试过了，没有的Top

3 楼beipiao（北漂）回复于 2005-07-15 14:04:01 得分 0

把编码前的数据和解码后的数据比较一下，看是否相同，不同的话，说明编解码有问题，否则就是显示有问题Top

4 楼psusong（栀子花开）回复于 2005-07-15 17:36:31 得分 0

楼上的做法是错误的,根本没有办法进行比较!,因为编码是个有损压缩的过程,解码后不可能完全复原!

我怀疑楼主的代码在实际中会有异常,因为解码的输出buffer的大小错误!

if( (dwResult == ICERR_OK) && (nCompressedSize > 0) )
{
//解压视频
char OutputData[512];//数据buffer的大小应该是176x144x3!
memset(OutputData, 0, 512);

DWORD dwRet;
dwRet = ICDecompress(m_hicDec, 0, &m_biDecInput.bmiHeader,
OutputBuf, &m_biDecOutput.bmiHeader, OutputData);
Top