2013-01-17 - a1a707f - lavf 54.61.100
Add av_codec_get_tag2().
-2012-12-20 - xxxxxxx - lavfi 3.28.100 - avfilter.h
+2012-12-20 - 34de47aa - lavfi 3.29.100 - avfilter.h
Add AVFilterLink.channels, avfilter_link_get_channels()
and avfilter_ref_get_channels().