diff --git a/src/image.zig b/src/image.zig
index 17a545d..28ca2ba 100644
--- a/src/image.zig
+++ b/src/image.zig
@@ -5,11 +5,11 @@ const custom = @import("custom.zig");
 
 const plugins = @import("plugin.zig");
 
-/// Approximate size of the BMP header.
+/// Approximate size of the BMP header, in bytes.
 pub const BMPHeaderSize: usize = 82000;
 
-/// Buffer size for main copying
-pub const BufferSize: usize = 60000;
+/// Buffer size for main image copying.
+pub const BufferSize: usize = 300000;
 
 pub const ImageError = error{
     OpenFail,
@@ -176,6 +176,7 @@ pub const Image = struct {
         return n_read == 1;
     }
 
+    /// Copy bytes from the current file to out_file.
     fn copyBytes(
         self: *Image,
         out_file: *c.SNDFILE,