From 6e65b5a285cd3f69c9cb3f5f8c3dd364aa118ab4 Mon Sep 17 00:00:00 2001
From: Xavier Henner <xavier@euclide.org>
Date: Wed, 20 May 2015 14:02:41 +0200
Subject: [PATCH] improve handling of corrupt frames

---
 mp3.go | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/mp3.go b/mp3.go
index e2a9dff..bb08974 100644
--- a/mp3.go
+++ b/mp3.go
@@ -95,23 +95,20 @@ func getMp3Infos(r io.ReadSeeker, slow bool) (*mp3Infos, error) {
 		if i < 4 {
 			break
 		}
-        if i==5 {
-            // invalid frame
-            continue
-        }
-		pos += int64(i)
 		// looking for the synchronization bits
 		switch {
 		case (buf[0] == 255) && (buf[1] >= 224):
 			// found a valid mp3 frame. we read the header to know where the
 			// next one is
-			pos, _ = r.Seek(h.readHeader(buf)-4, 1)
-
-			bitrateSum += h.Bitrate
-			frameCount++
-			if h.vbr > 2 {
-				nbscan = 100
+			offset := h.readHeader(buf) - 4
+			if offset != 1 { // only count valid frames
+				bitrateSum += h.Bitrate
+				frameCount++
+				if h.vbr > 2 {
+					nbscan = 100 // the file is VBR, use more sample to estimate its size
+				}
 			}
+			pos, _ = r.Seek(offset, 1) // jump to the next frame
 		case string(buf[:3]) == "TAG":
 			pos, _ = r.Seek(128-4, 1) // id3v1 tag, bypass it
 		default: