uint32 CCsoImageStream::ReadFromNextFrame(uint8* dest, uint64 maxBytes)
{
assert(!IsEOF());
const uint32 frame = static_cast<uint32>(m_position >> m_frameShift);
const uint32 offset = static_cast<uint32>(m_position - (frame << m_frameShift));
// This is how many bytes we will actually be reading from this frame.
const uint32 bytes = static_cast<uint32>(std::min(maxBytes, static_cast<uint64>(m_frameSize - offset)));
// Grab the index data for the frame we're about to read.
const bool compressed = (m_index[frame + 0] & 0x80000000) == 0;
const uint32 index0 = m_index[frame + 0] & 0x7FFFFFFF;
const uint32 index1 = m_index[frame + 1] & 0x7FFFFFFF;
// Calculate where the compressed payload is (if compressed.)
const uint64 frameRawPos = static_cast<uint64>(index0) << m_indexShift;
const uint64 frameRawSize = (index1 - index0) << m_indexShift;
if(!compressed)
{
// Just read directly, easy.
if(ReadBaseAt(frameRawPos + offset, dest, bytes) != bytes)
{
throw std::runtime_error("Unable to read uncompressed bytes from CSO.");
}
}
else
{
// We don't need to decompress if we already did this same frame last time.
if(m_zlibBufferFrame != frame)
{
// This might be less bytes than frameRawSize in case of padding on the last frame.
// This is because the index positions must be aligned.
const uint64 readRawBytes = ReadBaseAt(frameRawPos, m_readBuffer, frameRawSize);
DecompressFrame(frame, readRawBytes);
}
// Now we just copy the offset data from the cache.
memcpy(dest, m_zlibBuffer + offset, bytes);
}
return bytes;
}
void main()
{
unsigned char data[5000] ;
int i;
int n,size=2130;
FILE *f,*bmp;
char tstr[]="BM";
InitH263Decoder();
//Read from the file
f=fopen("h263","rb");
if(f==NULL)
{
printf("error in opening file");
return;
}
n=fread(data,sizeof(char),size,f);
if(n<size)
{
printf("total data read...%d \n terminating...",n);
return;
}
for(i=0;i<5;i++)
{
printf("\ndecompressing frame...%d",i);
int ret=DecompressFrame(data,size,rgbdata,80000);
if(ret)
printf("\n success");
else
{
printf("\n failure");
continue;
}
//Create bitmap file.....
bmp=fopen("my.bmp","wb");
if(bmp==NULL)
{
printf("unable to create bmp file");
return;
}
// Write 2 standard bytes .."BM"
fwrite(tstr,1,2,bmp);
// create and write file header
bfh.fsize=FILE_SIZE;
bfh.reserved=0;
bfh.offset=40+14;
fwrite(&bfh,1,sizeof(bfh),bmp);
//create and write bmp header
bih.bibitcount=24;
bih.biclrimp=0;
bih.biclrused=0;
bih.bicompression=0;
bih.biheight=IMAGE_HEIGHT;
bih.biplanes=1; //if does not work change it to 0
bih.bisize=40;
bih.bisizeimage=0;
bih.biwidth=IMAGE_WIDTH;
bih.bixpixelspermeter=0;
bih.biypixelspermeter=0;
fwrite(&bih,1,sizeof(bih),bmp);
// now write image data.....
fwrite(rgbdata,1,IMAGE_SIZE,bmp);
// close the file safely...
fclose(bmp);
}
// Finaly close the decoder safely....
ExitH263Decoder();
fclose(f);
}
