我刚刚使用带有位图锁定位的示例在我的 c++ 项目中创建了一个新函数：
void GetFrameData(Bitmap ^b)
{
typedef System::Drawing::Rectangle R;
R rect = R(0,0,b->Width,b->Height);
System::Drawing::Imaging::BitmapData^ bmpData = b->LockBits( rect, System::Drawing::Imaging::ImageLockMode::ReadWrite, b->PixelFormat );
// Get the address of the first line.
IntPtr ptr = bmpData->Scan0;
// Declare an array to hold the bytes of the bitmap.
// This code is specific to a bitmap with 24 bits per pixels.
int bytes = Math::Abs(bmpData->Stride) * b->Height;
array<Byte>^rgbValues = gcnew array<Byte>(bytes);
// Copy the RGB values into the array.
System::Runtime::InteropServices::Marshal::Copy( ptr, rgbValues, 0, bytes );
// Set every third value to 255.
for ( int counter = 2; counter < rgbValues->Length; counter += 3 )
rgbValues[ counter ] = 255;
// Copy the RGB values back to the bitmap
System::Runtime::InteropServices::Marshal::Copy( rgbValues, 0, ptr, bytes );
// Unlock the bits.
b->UnlockBits( bmpData );
}
该函数从 CSHARP 获取位图文件，不知何故我需要使用此锁定位将像素从位图复制到此函数：
void Encoder_start(char *filename)
{
printf("Encode video file %s\n", filename);
/* open it */
if (avcodec_open2(c, codec, NULL) < 0) {
fprintf(stderr, "Could not open codec\n");
exit(1);
}
// f = fopen(filename, "wb");
errn = fopen_s(&f,filename, "wb");
if (!f) {
fprintf(stderr, "Could not open %s\n", filename);
exit(1);
}
frame = avcodec_alloc_frame();
if (!frame) {
fprintf(stderr, "Could not allocate video frame\n");
exit(1);
}
frame->format = c->pix_fmt;
frame->width = c->width;
frame->height = c->height;
/* the image can be allocated by any means and av_image_alloc() is
* just the most convenient way if av_malloc() is to be used */
// ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,
// c->pix_fmt, 32);
frame->data[0] = (uint8_t*)av_malloc(1000000);
frame->data[1] = (uint8_t*)av_malloc(1000000);
frame->data[2] = (uint8_t*)av_malloc(1000000);
frame->data[3] = (uint8_t*)av_malloc(1000000);
frame->data[4] = (uint8_t*)av_malloc(1000000);
frame->data[5] = (uint8_t*)av_malloc(1000000);
frame->data[6] = (uint8_t*)av_malloc(1000000);
frame->data[7] = (uint8_t*)av_malloc(1000000);
if (frame->data[7]==0) {
//if (ret < 0) {
fprintf(stderr, "Could not allocate raw picture buffer\n");
exit(1);
}
total_frame_counter=0;
}
void Encoder_push_frame()
{
/* encode 1 second of video */
// for(i=0;i<25;i++) {
av_init_packet(&pkt);
pkt.data = NULL; // packet data will be allocated by the encoder
pkt.size = 0;
fflush(stdout);
/* prepare a dummy image */
/* Y */
for(y=0;y<c->height;y++) {
for(x=0;x<c->width;x++) {
frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
}
}
/* Cb and Cr */
for(y=0;y<c->height/2;y++) {
for(x=0;x<c->width/2;x++) {
frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
}
}
frame->pts = total_frame_counter;
total_frame_counter++;
/* encode the image */
ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
if (ret < 0) {
fprintf(stderr, "Error encoding frame\n");
exit(1);
}
if (got_output) {
printf("Write frame %3d (size=%5d)\n", total_frame_counter, pkt.size);
fwrite(pkt.data, 1, pkt.size, f);
av_free_packet(&pkt);
}
// }
}
我不确定如何填充以及我将每个位置设置为 1000000 的 av_malloc 以进行测试。
并且 Encoder_push_frame 函数应该获取像素，或者也许它与 av_malloc 的想法是用来自位图的像素填充 push_frame 函数中的图像。
我尝试了很多方法，但它根本不起作用。
编辑
我正在使用这段代码：
void GetFrameData(Bitmap ^b)
{
auto bmpData = b->LockBits( System::Drawing::Rectangle(0,0,b->Width,b->Height), ImageLockMode::ReadWrite, PixelFormat::Format24bppRgb );
// The beginning of the bitmap data in memory
char* top = bmpData->Scan0.ToPointer();
// find bitmap data for the top row (if bottom-up bitmap, this is at the end)
if (bmpData->Stride < 0) {
top += Stride * (1 - b->Height);
}
for( int y = 0; y < b->Height; ++y ) {
RGBTRIPLE* row = (RGBTRIPLE*)(top + y * bmpData->Stride);
// saturate red channel
for( int x = 0; x < b->Width; ++x ) {
row[x].rgbtBlue = 255;
row[x].rgbtGreen = 255;
row[x].rgbtRed = 255;
}
// Unlock the bits.
b->UnlockBits( bmpData );
}
在 Rectangle 中，我必须将其更改为： System::Drawing::Rectangle 如果不是，那么我在 Rectangle 上有一个错误，它与另一个 Rectangle 发生冲突。但是现在改变它之后，我在这一行的 bmpData 上有一个错误：
char* top = bmpData->Scan0.ToPointer();
IntelliSense：“void *”类型的值不能用于初始化“char *”类型的实体
第二个错误出现在 Stride 上：
top += Stride * (1 - b->Height);
错误：智能感知：标识符“步幅”未定义
我该如何解决这个错误。
和：
将 for 循环更改为：
for( int x = 0; x < b->Width; ++x ) {
row[x].rgbtBlue = 255;
row[x].rgbtGreen = 255;
row[x].rgbtRed = 255;
我改变它的原因是你做了 row[x].R = 255; 但是 R 不存在/未定义，所以我应该怎么做才能解决它？（我想我做错了）。