將位圖保存到視頻（libavcodec ffmpeg）

Question

我想使用libavcodec將HBitmap轉換爲視頻流。 我用得到我的HBITMAP：

HBITMAP hCaptureBitmap =CreateCompatibleBitmap(hDesktopDC, nScreenWidth, nScreenHeight); 
SelectObject(hCaptureDC,hCaptureBitmap); 
BitBlt(hCaptureDC,0,0,nScreenWidth,nScreenHeight,hDesktopDC,0,0,SRCCOPY); 

，我想將其轉換爲YUV（這是由我使用的編解碼器需要）。爲此我使用：

SwsContext *fooContext = sws_getContext(c->width,c->height,PIX_FMT_BGR32, c->width,c->height,PIX_FMT_YUV420P,SWS_FAST_BILINEAR,NULL,NULL,NULL); 

uint8_t *movie_dib_bits = reinterpret_cast<uint8_t *>(bm.bmBits) + bm.bmWidthBytes * (bm.bmHeight - 1); 

int dibrowbytes = -bm.bmWidthBytes; 

uint8_t* data_out[1]; 
int stride_out[1]; 
data_out[0] = movie_dib_bits; 
stride_out[0] = dibrowbytes; 

sws_scale(fooContext,data_out,stride_out,0,c->height,picture->data,picture->linesize); 

但是，這根本不起作用......任何想法爲什麼？或者我怎樣才能做到這一點？

謝謝！

Answer 1

我不熟悉您正在使用得到位圖的東西，但假設它是正確的，你有一個指針BGR 32位/像素數據，嘗試這樣的事情：

uint8_t* inbuffer; 
int in_width, in_height, out_width, out_height; 

//here, make sure inbuffer points to the input BGR32 data, 
//and the input and output dimensions are set correctly. 

//calculate the bytes needed for the output image 
int nbytes = avpicture_get_size(PIX_FMT_YUV420P, out_width, out_height); 

//create buffer for the output image 
uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes); 

//create ffmpeg frame structures. These do not allocate space for image data, 
//just the pointers and other information about the image. 
AVFrame* inpic = avcodec_alloc_frame(); 
AVFrame* outpic = avcodec_alloc_frame(); 

//this will set the pointers in the frame structures to the right points in 
//the input and output buffers. 
avpicture_fill((AVPicture*)inpic, inbuffer, PIX_FMT_BGR32, in_width, in_height); 
avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, out_width, out_height); 

//create the conversion context 
SwsContext* fooContext = sws_getContext(in_width, in_height, PIX_FMT_BGR32, out_width, out_height, PIX_FMT_YUV420P, SWS_FAST_BILINEAR, NULL, NULL, NULL); 

//perform the conversion 
sws_scale(fooContext, inpic->data, inpic->linesize, 0, in_height, outpic->data, outpic->linesize); 

//encode the frame here... 

//free memory 
av_free(outbuffer); 
av_free(inpic); 
av_free(outpic); 

當然，如果您要轉換一系列幀，只需在開始時進行一次分配，並在末尾釋放一次。