pFrameRGB=av_frame_alloc();
int numBytes=avpicture_get_size(AV_PIX_FMT_BGR24, pCodecCtx->width, pCodecCtx->height);
out_buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
avpicture_fill((AVPicture *)pFrameRGB, out_buffer, AV_PIX_FMT_BGR24, pCodecCtx->width, pCodecCtx->height);
struct SwsContext *img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_BGR24, SWS_BILINEAR, NULL, NULL, NULL);
sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0,
pCodecCtx->height, pFrameRGB->data,pFrameRGB->linesize);