d2phap/ImageGlass · error · Exception

Can't allocate memory in WebPPictureImportBGRA

Error message

Can't allocate memory in WebPPictureImportBGRA

What it means

Thrown by AdvancedEncode when LibWebp.WebPPictureImportBGRA returns != 1 for a Format32bppArgb bitmap. The import copies source pixels into a libwebp-owned ARGB buffer; a 0 return means the import failed, most often due to an allocation failure for very large pictures or a corrupt WebPPicture state.

Source

Thrown at v9/Components/ImageGlass.WebP/WebPWrapper.cs:896

            if (bmp.Width > WEBP_MAX_DIMENSION || bmp.Height > WEBP_MAX_DIMENSION)
                throw new NotSupportedException($"Bitmap's dimension is too large. Max is {WEBP_MAX_DIMENSION}x{WEBP_MAX_DIMENSION} pixels.");
            if (bmp.PixelFormat != PixelFormat.Format24bppRgb && bmp.PixelFormat != PixelFormat.Format32bppArgb)
                throw new NotSupportedException("Only support Format24bppRgb and Format32bppArgb pixelFormat.");

            // Setup the input data, allocating a the bitmap, width and height
            bmpData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, bmp.PixelFormat);
            if (LibWebp.WebPPictureInitInternal(ref wpic) != 1)
                throw new Exception("Can't initialize WebPPictureInit");
            wpic.width = (int)bmp.Width;
            wpic.height = (int)bmp.Height;
            wpic.use_argb = 1;

            if (bmp.PixelFormat == PixelFormat.Format32bppArgb)
            {
                // Put the bitmap componets in wpic
                int result = LibWebp.WebPPictureImportBGRA(ref wpic, bmpData.Scan0, bmpData.Stride);
                if (result != 1)
                    throw new Exception("Can't allocate memory in WebPPictureImportBGRA");
                wpic.colorspace = (uint)WEBP_CSP_MODE.MODE_bgrA;
                dataWebpSize = bmp.Width * bmp.Height * 32;
                dataWebp = new byte[bmp.Width * bmp.Height * 32]; // Memory for WebP output
            }
            else
            {
                // Put the bitmap contents in WebPPicture instance
                int result = LibWebp.WebPPictureImportBGR(ref wpic, bmpData.Scan0, bmpData.Stride);
                if (result != 1)
                    throw new Exception("Can't allocate memory in WebPPictureImportBGR");
                dataWebpSize = bmp.Width * bmp.Height * 24;

            }

            // Set up statistics of compression
            if (info)
            {
                stats = new WebPAuxStats();

View on GitHub (pinned to 4a3c4fecef)

Solutions

1. Reduce bitmap dimensions before encoding to lower the ARGB buffer requirement.
2. Run as a 64-bit process to raise the address-space ceiling.
3. Avoid concurrent advanced encodes that double peak memory.
4. Ensure WebPPictureInitInternal succeeded (which the wrapper checks just before) so wpic is clean.

Example fix

// before
var bytes = webp.EncodeLossy(bigArgb, quality, speed); // may exhaust memory

// after
using var smaller = new Bitmap(bigArgb.Width / 2, bigArgb.Height / 2, PixelFormat.Format32bppArgb);
using (var g = Graphics.FromImage(smaller)) g.DrawImage(bigArgb, 0, 0, smaller.Width, smaller.Height);
var bytes = webp.EncodeLossy(smaller, quality, speed);

// Lower the working set for very large 32bpp images before the BGRA import
if (Environment.Is64BitProcess == false && bmp.Width * bmp.Height > 50_000_000)
    bmp = DownscaleTo(bmp, Math.Max(bmp.Width / 2, 1), Math.Max(bmp.Height / 2, 1), PixelFormat.Format32bppArgb);

static bool LikelyFitsInMemory(Bitmap bmp) =>
    (long)bmp.Width * bmp.Height * 4 < (Environment.Is64BitProcess ? 1L << 40 : 1_500_000_000L);

try { var bytes = webp.EncodeLossy(bmp, quality, speed); }
catch (Exception ex) when (ex.Message.Contains("WebPPictureImportBGRA"))
{ bmp = DownscaleTo(bmp, bmp.Width / 2, bmp.Height / 2, PixelFormat.Format32bppArgb); /* retry */ }

When it happens

Trigger: Advanced encode of a Format32bppArgb bitmap where WebPPictureImportBGRA cannot allocate/import — large dimensions near the memory ceiling, a 32-bit process running out of address space, or a wpic struct left in a bad state.

Common situations: Encoding huge 32bpp images on x86; concurrent encodes exhausting memory; a prior failed init leaving wpic partially initialized.

Related errors

• Can't allocate memory in WebPPictureImportBGR
• Encoding error: {error_code}
• Can't encode WebP
• Bad configuration parameters
• Can't initialize WebPPictureInit

AI-assisted analysis of d2phap/ImageGlass@4a3c4fecef (2026-08-13). Data as JSON: /api/errors/d1c70073120b2677. Report an issue: GitHub.