Revert "prober: Run sox with "-t mp3" in all cases"

This reverts commit 5e3184fef774c3eb8a77fa5410e18ee8cee3f7fb.

prober/decoder.go

@@ -22,9 +22,7 @@ type decoder struct {
 }
 
 func newDecoder(r io.Reader) (*decoder, error) {
-	// Here we use '-t mp3' for all formats, as sox will do the
-	// right thing anyway (autodetect) for ogg-format streams.
-	cmd := exec.Command("sox", "-t", "mp3", "-", "-r", analysisSampleRate, "-c", analysisChannels, "-b", "64", "-e", "float", "--endian", "little", "-t", "raw", "-")
+	cmd := exec.Command("sox", "-", "-r", analysisSampleRate, "-c", analysisChannels, "-b", "64", "-e", "float", "--endian", "little", "-t", "raw", "-")
 	cmd.Stdin = r
 	cmd.Stderr = os.Stderr
 	stdout, err := cmd.StdoutPipe()