將位圖保存到視頻（libavcodec ffmpeg）

Question

我想使用libavcodec將HBitmap轉換為視頻流。 我使用以下方法獲取HBitmap：

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

我想將其轉換為YUV（我正在使用的編解碼器要求）。 為此，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);  

但這根本不起作用...為什么知道呢？ 或者我該怎么做呢？

謝謝 ！

Answer 1

我不熟悉用於獲取位圖的內容，但是假設它是正確的並且您有一個指向BGR 32位/像素數據的指針，請嘗試如下操作：

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，如果要轉換一系列幀，只需在開始時分配一次，在結束時分配一次。