enhance embed custom plugin

- seek to 0 on setup
 - ignore and copy original bytes if we reached end of audio file

src/custom.zig

@@ -164,6 +164,8 @@ pub const Embed = struct {
             &in_fmt,
         );
 
+        image.sseek(self.sndfile, 0);
+
         self.buf = try self.allocator.alloc(f32, @intCast(usize, in_fmt.channels));
     }
 
@@ -173,7 +175,7 @@ pub const Embed = struct {
         const read_bytes = c.sf_readf_float(self.sndfile, self.buf.ptr, 1);
 
         if (read_bytes == 0) {
-            std.debug.warn("WARN! reached EOF for embed\n");
+            bufs.out[0] = bufs.in[0];
             return;
         }
 

src/image.zig

@@ -65,7 +65,7 @@ pub fn swrite(file: *c.SNDFILE, buf: [*]f32, frames: i64) !void {
     }
 }
 
-fn sseek(file: *c.SNDFILE, offset: usize) void {
+pub fn sseek(file: *c.SNDFILE, offset: usize) void {
     const offset_i64 = @intCast(i64, offset);
     const frames = c.sf_seek(file, offset_i64, c.SEEK_SET);
     const frames_current = c.sf_seek(file, 0, c.SEEK_CUR);