Patch libav to avoid waveformatextensible header in AVI with >2 channels audio streams

nowaveformatextensible.patch

--- a/libavformat/riffenc.c	2014-02-23 22:59:10.000000000 +0100
+++ b/libavformat/riffenc.c	2014-03-26 15:12:11.000000000 +0100
@@ -70,7 +70,10 @@
     if (!frame_size)
         frame_size = enc->frame_size;
 
-    waveformatextensible = (enc->channels > 2 && enc->channel_layout) ||
+    /* Patched libav to avoid waveformatextensible header in AVI with
+     * >2 channels audio streams to improve compatibility as per
+     * http://ffmpeg-users.933282.n4.nabble.com/AC3-encoding-problem-wrong-audio-tag-tp4651779p4651810.html */
+    waveformatextensible = (enc->channels > 20 && enc->channel_layout) ||
                            enc->sample_rate > 48000 ||
                            av_get_bits_per_sample(enc->codec_id) > 16;
 

Updated for ffmpeg 2.0+