Merge commit '22a6d48b0d7367b3a45dd6db245f8ffaaa364995'

* commit '22a6d48b0d7367b3a45dd6db245f8ffaaa364995':
  avconv: Print the avfilter errors

Conflicts:
	ffmpeg.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg.c

@@ -3853,11 +3853,15 @@ static int transcode(void)
 
         ret = transcode_step();
         if (ret < 0) {
-            if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN))
+            if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN)) {
                 continue;
+            } else {
+                char errbuf[128];
+                av_strerror(ret, errbuf, sizeof(errbuf));
 
-            av_log(NULL, AV_LOG_ERROR, "Error while filtering.\n");
-            break;
+                av_log(NULL, AV_LOG_ERROR, "Error while filtering: %s\n", errbuf);
+                break;
+            }
         }
 
         /* dump report by using the output first video and audio streams */