diff --git a/check/main.go b/check/main.go
new file mode 100644
index 0000000..b199763
--- /dev/null
+++ b/check/main.go
@@ -0,0 +1,183 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/dhowden/itl"
+	"github.com/dhowden/tag"
+)
+
+var itlXML, path string
+var sum bool
+
+func init() {
+	flag.StringVar(&itlXML, "itlXML", "", "iTunes Library Path")
+	flag.StringVar(&path, "path", "", "path to directory containing audio files")
+	flag.BoolVar(&sum, "sum", false, "compute the checksum of the audio file (doesn't work for .flac or .ogg yet)")
+}
+
+func decodeLocation(l string) (string, error) {
+	u, err := url.ParseRequestURI(l)
+	if err != nil {
+		return "", err
+	}
+	// Annoyingly this doesn't replace & (&)
+	path := strings.Replace(u.Path, "&", "&", -1)
+	return path, nil
+}
+
+func main() {
+	flag.Parse()
+
+	if itlXML == "" && path == "" || itlXML != "" && path != "" {
+		fmt.Println("you must specify one of -itlXML or -path")
+		os.Exit(1)
+	}
+
+	var paths <-chan string
+	if itlXML != "" {
+		var err error
+		paths, err = walkLibrary(itlXML)
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+	}
+
+	if path != "" {
+		paths = walkPath(path)
+	}
+
+	p := &processor{
+		decodingErrors: make(map[string]int),
+		hashErrors:     make(map[string]int),
+		hashes:         make(map[string]int),
+	}
+
+	done := make(chan bool)
+	go func() {
+		p.do(paths)
+		fmt.Println(p)
+		close(done)
+	}()
+	<-done
+}
+
+func walkPath(root string) <-chan string {
+	ch := make(chan string)
+	fn := func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+		ch <- path
+		return nil
+	}
+
+	go func() {
+		err := filepath.Walk(root, fn)
+		if err != nil {
+			fmt.Println(err)
+		}
+		close(ch)
+	}()
+	return ch
+}
+
+func walkLibrary(path string) (<-chan string, error) {
+	f, err := os.Open(itlXML)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	l, err := itl.ReadFromXML(f)
+	if err != nil {
+		return nil, err
+	}
+
+	paths := make(chan string)
+	go func() {
+		for _, t := range l.Tracks {
+			loc, err := decodeLocation(t.Location)
+			if err != nil {
+				fmt.Println(err)
+				break
+			}
+			paths <- loc
+		}
+		close(paths)
+	}()
+	return paths, nil
+}
+
+type processor struct {
+	decodingErrors map[string]int
+	hashErrors     map[string]int
+	hashes         map[string]int
+}
+
+func (p *processor) String() string {
+	result := ""
+	for k, v := range p.decodingErrors {
+		result += fmt.Sprintf("%v : %v\n", k, v)
+	}
+
+	for k, v := range p.hashErrors {
+		result += fmt.Sprintf("%v : %v\n", k, v)
+	}
+
+	for k, v := range p.hashErrors {
+		if v > 1 {
+			result += fmt.Sprintf("%v : %v\n", k, v)
+		}
+	}
+	return result
+}
+
+func (p *processor) do(ch <-chan string) {
+	for path := range ch {
+		func() {
+			defer func() {
+				if p := recover(); p != nil {
+					fmt.Printf("Panicing at: %v", path)
+					panic(p)
+				}
+			}()
+			tf, err := os.Open(path)
+			if err != nil {
+				p.decodingErrors["error opening file"]++
+				return
+			}
+			defer tf.Close()
+
+			_, err = tag.ReadFrom(tf)
+			if err != nil {
+				fmt.Println("READFROM:", path, err.Error())
+				p.decodingErrors[err.Error()]++
+			}
+
+			if sum {
+				_, err = tf.Seek(0, os.SEEK_SET)
+				if err != nil {
+					fmt.Println("DIED:", path, "error seeking back to 0:", err)
+					return
+				}
+
+				h, err := tag.Sum(tf)
+				if err != nil {
+					fmt.Println("SUM:", path, err.Error())
+					p.hashErrors[err.Error()]++
+				}
+				p.hashes[h]++
+			}
+		}()
+	}
+}