From ab2960970171ce3c988405f99a517b9a2fd6496e Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Sun, 5 Aug 2012 08:37:43 +0200
Subject: [PATCH] avconv: allow no input files.

It is now possible to use lavfi sources.
---
 avconv.c        | 5 -----
 doc/avconv.texi | 8 ++++++++
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/avconv.c b/avconv.c
index 2566a92c14..2bc9d82378 100644
--- a/avconv.c
+++ b/avconv.c
@@ -2431,11 +2431,6 @@ int main(int argc, char **argv)
         exit_program(1);
     }
 
-    if (nb_input_files == 0) {
-        av_log(NULL, AV_LOG_FATAL, "At least one input file must be specified\n");
-        exit_program(1);
-    }
-
     ti = getutime();
     if (transcode() < 0)
         exit_program(1);
diff --git a/doc/avconv.texi b/doc/avconv.texi
index 776a326369..ff5bb5297c 100644
--- a/doc/avconv.texi
+++ b/doc/avconv.texi
@@ -805,6 +805,9 @@ the matching type.
 Output link labels are referred to with @option{-map}. Unlabeled outputs are
 added to the first output file.
 
+Note that with this option it is possible to use only lavfi sources without
+normal input files.
+
 For example, to overlay an image over video
 @example
 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
@@ -827,6 +830,11 @@ graph will be added to the output file automatically, so we can simply write
 @example
 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
 @end example
+
+To generate 5 seconds of pure red video using lavfi @code{color} source:
+@example
+avconv -filter_complex 'color=red' -t 5 out.mkv
+@end example
 @end table
 @c man end OPTIONS