[FFmpeg-cvslog] doc/examples/decode_video: add input file format information for usage

[Steven Liu]

ffmpeg | branch: master | Steven Liu <lq at chinaffmpeg.org> | Wed Aug 21 19:34:49 2019 +0800| [6d1009cb9d888996c544a3ee95245b0df44bb2e0] | committer: Steven Liu

doc/examples/decode_video: add input file format information for usage

Signed-off-by: Steven Liu <lq at chinaffmpeg.org>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6d1009cb9d888996c544a3ee95245b0df44bb2e0
---

 doc/examples/decode_video.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/examples/decode_video.c b/doc/examples/decode_video.c
index 5a9d43f689..169188a4b9 100644
--- a/doc/examples/decode_video.c
+++ b/doc/examples/decode_video.c
@@ -95,7 +95,8 @@ int main(int argc, char **argv)
     AVPacket *pkt;
 
     if (argc <= 2) {
-        fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
+        fprintf(stderr, "Usage: %s <input file> <output file>\n"
+                "And check your input file is encoded by mpeg1video please.\n", argv[0]);
         exit(0);
     }
     filename    = argv[1];