faq: suggest the concat filter.

doc/faq.texi

@@ -252,6 +252,15 @@ the other; it can be done using the
 @anchor{How can I concatenate video files}
 @section How can I concatenate video files?
 
+There are several solutions, depending on the exact circumstances.
+
+@subsection Concatenating using filters
+
+FFmpeg has a @url{http://ffmpeg.org/ffmpeg.html#concat-1, @code{concat}}
+filter designed specifically for that, with examples in the documentation.
+
+@subsection Concatenating at the file level
+
 A few multimedia containers (MPEG-1, MPEG-2 PS, DV) allow to concatenate
 video by merely concatenating the files them.
 
@@ -291,6 +300,8 @@ cat intermediate1.mpg intermediate2.mpg |\
 ffmpeg -f mpeg -i - -qscale:v 2 -c:v mpeg4 -acodec libmp3lame -q:a 4 output.avi
 @end example
 
+@subsection Concatenating using raw audio and video
+
 Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also
 allow concatenation, and the transcoding step is almost lossless.
 When using multiple yuv4mpegpipe(s), the first line needs to be discarded