Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
/// <summary>
/// Transform NV12 to bmp image so we can view how is it looks like. Note it's not NV12 to RBG conversion.
/// </summary>
/// <param name="data">NV12 sample data.</param>
/// <param name="width">Image width.</param>
/// <param name="height">Image height.</param>
/// <param name="logger">Log instance.</param>
/// <returns>The <see cref="Bitmap"/>.</returns>
public static Bitmap TransformNv12ToBmpFaster(byte[] data, int width, int height, IGraphLogger logger)
{
Stopwatch watch = new Stopwatch();
watch.Start();
var bmp = new Bitmap(width, height, PixelFormat.Format32bppPArgb);
var bmpData = bmp.LockBits(
new Rectangle(0, 0, bmp.Width, bmp.Height),
ImageLockMode.ReadWrite,
PixelFormat.Format32bppRgb);
var uvStart = width * height;
for (var y = 0; y < height; y++)
{
var pos = y * width;
var posInBmp = y * bmpData.Stride;
for (var x = 0; x < width; x++)
{
var vIndex = uvStart + ((y >> 1) * width) + (x & ~1);
//// https://msdn.microsoft.com/en-us/library/windows/desktop/dd206750(v=vs.85).aspx
//// https://en.wikipedia.org/wiki/YUV
var c = data[pos] - 16;
var d = data[vIndex] - 128;
var e = data[vIndex + 1] - 128;
c = c < 0 ? 0 : c;
var r = ((298 * c) + (409 * e) + 128) >> 8;
var g = ((298 * c) - (100 * d) - (208 * e) + 128) >> 8;
var b = ((298 * c) + (516 * d) + 128) >> 8;
r = r.Clamp(0, 255);
g = g.Clamp(0, 255);
b = b.Clamp(0, 255);
Marshal.WriteInt32(bmpData.Scan0, posInBmp + (x << 2), (b << 0) | (g << 8) | (r << 16) | (0xFF << 24));
pos++;
}
}
bmp.UnlockBits(bmpData);
watch.Stop();
logger.Info($"Took {watch.ElapsedMilliseconds} ms to lock and unlock");
return bmp;
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment