From f32097e0df8aa256fc360d3d8d8a0996e039515d Mon Sep 17 00:00:00 2001
From: Pascal Massimino <pascal.massimino@gmail.com>
Date: Mon, 10 Jun 2013 05:46:22 -0700
Subject: [PATCH] probe input file and quick-check for WebP format.

Error message is clearer that 'can't create demux object'.

Change-Id: Iec008601892f7cd8399e1948751747ac23305eef
(cherry picked from commit 830f72b7e988ae0650435f7a285d12e098d7e6ae)
---
 examples/vwebp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/examples/vwebp.c b/examples/vwebp.c
index df389a61..f13b88fc 100644
--- a/examples/vwebp.c
+++ b/examples/vwebp.c
@@ -436,6 +436,11 @@ int main(int argc, char *argv[]) {
     goto Error;
   }
 
+  if (!WebPGetInfo(kParams.data.bytes, kParams.data.size, NULL, NULL)) {
+    fprintf(stderr, "Input file doesn't appear to be WebP format.\n");
+    goto Error;
+  }
+
   kParams.dmux = WebPDemux(&kParams.data);
   if (kParams.dmux == NULL) {
     fprintf(stderr, "Could not create demuxing object!\n");