我使用FFmpeg库version 4.0来创建简单的C ++程序，这是一个从IP摄像头接收RTSP H264视频数据并在程序窗口中显示它的线程。
此主题的代码如下：
DWORD WINAPI GrabbProcess(LPVOID lpParam)
// Grabbing thread
{
DWORD i;
int ret = 0, nPacket=0;
FILE *pktFile;
// Open video file
pFormatCtx = avformat_alloc_context();
if(avformat_open_input(&pFormatCtx, nameVideoStream, NULL, NULL)!=0)
fGrabb=-1; // Couldn't open file
else
// Retrieve stream information
if(avformat_find_stream_info(pFormatCtx, NULL)<0)
fGrabb=-2; // Couldn't find stream information
else
{
// Find the first video stream
videoStream=-1;
for(i=0; i<pFormatCtx->nb_streams; i++)
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
{
videoStream=i;
break;
}
if(videoStream==-1)
fGrabb=-3; // Didn't find a video stream
else
{
// Get a pointer to the codec context for the video stream
pCodecCtxOrig=pFormatCtx->streams[videoStream]->codec;
// Find the decoder for the video stream
pCodec=avcodec_find_decoder(pCodecCtxOrig->codec_id);
if(pCodec==NULL)
fGrabb=-4; // Codec not found
else
{
// Copy context
pCodecCtx = avcodec_alloc_context3(pCodec);
if(avcodec_copy_context(pCodecCtx, pCodecCtxOrig) != 0)
fGrabb=-5; // Error copying codec context
else
{
// Open codec
if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
fGrabb=-6; // Could not open codec
else
// Allocate video frame for input
pFrame=av_frame_alloc();
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width,
pCodecCtx->height);
buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
// Assign appropriate parts of buffer to image planes in pFrame
// Note that pFrame is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrame, buffer, pCodecCtx->pix_fmt,
pCodecCtx->width, pCodecCtx->height);
// Allocate video frame for display
pFrameRGB=av_frame_alloc();
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx->width,
pCodecCtx->height);
bufferRGB=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
// Assign appropriate parts of buffer to image planes in pFrameRGB
// Note that pFrameRGB is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrameRGB, bufferRGB, AV_PIX_FMT_RGB24,
pCodecCtx->width, pCodecCtx->height);
// initialize SWS context for software scaling to FMT_RGB24
sws_ctx_to_RGB = sws_getContext(pCodecCtx->width,
pCodecCtx->height,
pCodecCtx->pix_fmt,
pCodecCtx->width,
pCodecCtx->height,
AV_PIX_FMT_RGB24,
SWS_BILINEAR,
NULL,
NULL,
NULL);
// Allocate video frame (grayscale YUV420P) for processing
pFrameYUV=av_frame_alloc();
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width,
pCodecCtx->height);
bufferYUV=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
// Assign appropriate parts of buffer to image planes in pFrameYUV
// Note that pFrameYUV is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrameYUV, bufferYUV, AV_PIX_FMT_YUV420P,
pCodecCtx->width, pCodecCtx->height);
// initialize SWS context for software scaling to FMT_YUV420P
sws_ctx_to_YUV = sws_getContext(pCodecCtx->width,
pCodecCtx->height,
pCodecCtx->pix_fmt,
pCodecCtx->width,
pCodecCtx->height,
AV_PIX_FMT_YUV420P,
SWS_BILINEAR,
NULL,
NULL,
NULL);
RealBsqHdr.biWidth = pCodecCtx->width;
RealBsqHdr.biHeight = -pCodecCtx->height;
}
}
}
}
while ((fGrabb==1)||(fGrabb==100))
{
// Grabb a frame
if (av_read_frame(pFormatCtx, &packet) >= 0)
{
// Is this a packet from the video stream?
if(packet.stream_index==videoStream)
{
// Decode video frame
int len = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
nPacket++;
// Did we get a video frame?
if(frameFinished)
{
// Convert the image from its native format to YUV
sws_scale(sws_ctx_to_YUV, (uint8_t const * const *)pFrame->data,
pFrame->linesize, 0, pCodecCtx->height,
pFrameYUV->data, pFrameYUV->linesize);
// Convert the image from its native format to RGB
sws_scale(sws_ctx_to_RGB, (uint8_t const * const *)pFrame->data,
pFrame->linesize, 0, pCodecCtx->height,
pFrameRGB->data, pFrameRGB->linesize);
HDC hdc=GetDC(hWndM);
SetDIBitsToDevice(hdc, 0, 0, pCodecCtx->width, pCodecCtx->height,
0, 0, 0, pCodecCtx->height,pFrameRGB->data[0], (LPBITMAPINFO)&RealBsqHdr, DIB_RGB_COLORS);
ReleaseDC(hWndM,hdc);
av_frame_unref(pFrame);
}
}
// Free the packet that was allocated by av_read_frame
av_free_packet(&packet);
}
}
// Free the org frame
av_frame_free(&pFrame);
// Free the RGB frame
av_frame_free(&pFrameRGB);
// Free the YUV frame
av_frame_free(&pFrameYUV);
// Close the codec
avcodec_close(pCodecCtx);
avcodec_close(pCodecCtxOrig);
// Close the video file
avformat_close_input(&pFormatCtx);
avformat_free_context(pFormatCtx);
if (fGrabb==1)
sprintf(tmpstr,"Grabbing Completed %d frames", nCntTotal);
else if (fGrabb==2)
sprintf(tmpstr,"User break on %d frames", nCntTotal);
else if (fGrabb==3)
sprintf(tmpstr,"Can't Grabb at frame %d", nCntTotal);
else if (fGrabb==-1)
sprintf(tmpstr,"Couldn't open file");
else if (fGrabb==-2)
sprintf(tmpstr,"Couldn't find stream information");
else if (fGrabb==-3)
sprintf(tmpstr,"Didn't find a video stream");
else if (fGrabb==-4)
sprintf(tmpstr,"Codec not found");
else if (fGrabb==-5)
sprintf(tmpstr,"Error copying codec context");
else if (fGrabb==-6)
sprintf(tmpstr,"Could not open codec");
i=(UINT) fGrabb;
fGrabb=0;
SetWindowText(hWndM,tmpstr);
ExitThread(i);
return 0;
}
// End Grabbing thread
当节目收到分辨率为RTSP H264的{{1}}视频数据时，解码的视频图片就可以了。当收到分辨率为704x576的{{1}}高清视频数据时，看起来第一个视频图片被解码为OK，然后视频图片被解码但总是出现一些错误。
请帮我解决这个问题！
以下是问题简述：
我有一个IP摄像头模型RTSP H264（中国的产品）
Camera可以分辨率704x576（RTSP URI“rtsp：//192.168.1.18：554 / user = admin_password = tlJwpbo6_channel = 1_stream = 1.sdp？real_stream”）或1280x720（RTSP URI“rtsp：/”）提供H264视频流/192.168.1.18:554/user=admin_password=tlJwpbo6_channel=1_stream=0.sdp?real_stream“）。
使用1280x720实用程序，我可以访问并以良好的图像质量显示它们
为了测试从这台相机获取，我在VC-2005中有一个简单的（上面提到的）程序。在“Grabbing thread”程序中，使用HI3518E_50H10L_S39库版本4.0打开相机RTSP流，检索流信息，查找第一个视频流......并准备一些变量。
循环的中心是循环：抓取一个帧（函数FFplay） - 如果是视频（函数FFmpeg）解码它 - 转换为RGB格式（函数av_read_frame） - 显示到程序窗口（GDI函数avcodec_decode_video2）。
当proram使用分辨率为704x576的相机RTSP流运行时，我有很好的视频图像。这是一个例子：
704x576 sample
当程序使用分辨率为1280x720的相机RTSP流运行时，第一个视频图像是好的：
First good at res.1280x720
但后来不好：
not good at res.1280x720
它似乎是我对sws_scale的FFmpeg函数调用由于某些原因无法完全解码某些数据包。
