Crash Variant #1 Sometimes flvtool2 1.0.6 crashes on FLVs created by ffmpeg or mencoder. The FLV video itself is playable without the metadata and looks fine, still flvtool2 crashes like this: $ flvtool2 -kUP -metadatacreator:'some label' video.flv ERROR: EOFError ERROR: /usr/lib/ruby/site_ruby/1.8/flv/amf_string_buffer.rb:37:in `read' ERROR: /usr/lib/ruby/site_ruby/1.8/flv/amf_string_buffer.rb:243:in `read__STRING' ERROR: /usr/lib/ruby/site_ruby/1.8/flv/audio_tag.rb:56:in `read_header' ERROR: /usr/lib/ruby/site_ruby/1.8/flv/audio_tag.rb:47:in `after_initialize' ERROR: /usr/lib/ruby/site_ruby/1.8/flv/tag.rb:56:in `initialize' ERROR: /usr/lib/ruby/site_ruby/1.8/flv/stream.rb:447:in `new' ERROR: /usr/lib/ruby/site_ruby/1.8/flv/stream.rb:447:in `read_tags' ERROR: /usr/lib/ruby/site_ruby/1.8/flv/stream.rb:58:in `initialize' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2/base.rb:272:in `new' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2/base.rb:272:in `open_stream' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2/base.rb:238:in `process_files' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2/base.rb:225:in `each' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2/base.rb:225:in `process_files' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2/base.rb:44:in `execute!' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2.rb:168:in `execute!' ERROR: /usr/lib/ruby/site_ruby/1.8/flvtool2.rb:228 ERROR: /usr/bin/flvtool2:2:in `require' ERROR: /usr/bin/flvtool2:2 $ In the Wowza Media Server support forum is a hint on how to patch flvtool2 to solve the issue: 
--- /usr/local/lib/site_ruby/1.8/flv/audio_tag.rb	2009-11-12 10:46:13.000000000 +0100
+++ lib/flv/audio_tag.rb	2010-03-17 11:25:35.000000000 +0100
@@ -44,7 +44,9 @@
     
     def after_initialize(new_object)
       @tag_type = AUDIO
-      read_header
+      if data_size > 0
+      	read_header
+      end
     end
 
     def name
Crash Variant #2 Here is another crashing variant: $ flvtool2 -kUP -metadatacreator:'some label' video.flv ERROR: EOFError ERROR: /usr/local/lib/site_ruby/1.8/flv/amf_string_buffer.rb:37:in `read' ERROR: /usr/local/lib/site_ruby/1.8/flv/amf_string_buffer.rb:75:in `read__AMF_string' ERROR: /usr/local/lib/site_ruby/1.8/flv/amf_string_buffer.rb:90:in `read__AMF_mixed_array' ERROR: /usr/local/lib/site_ruby/1.8/flv/amf_string_buffer.rb:134:in `read__AMF_data' ERROR: /usr/local/lib/site_ruby/1.8/flv/meta_tag.rb:40:in `after_initialize' ERROR: /usr/local/lib/site_ruby/1.8/flv/tag.rb:56:in `initialize' ERROR: /usr/local/lib/site_ruby/1.8/flv/stream.rb:451:in `new' ERROR: /usr/local/lib/site_ruby/1.8/flv/stream.rb:451:in `read_tags' ERROR: /usr/local/lib/site_ruby/1.8/flv/stream.rb:58:in `initialize' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2/base.rb:272:in `new' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2/base.rb:272:in `open_stream' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2/base.rb:238:in `process_files' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2/base.rb:225:in `each' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2/base.rb:225:in `process_files' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2/base.rb:44:in `execute!' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2.rb:168:in `execute!' ERROR: /usr/local/lib/site_ruby/1.8/flvtool2.rb:228 ERROR: /usr/local/bin/flvtool2:2:in `require' ERROR: /usr/local/bin/flvtool2:2 $ I have not yet found a solution... Update: I have found crash variant #2 to often happen with larger files. Using flvtool++ instead of flvtool2 always solved the problem. Using flvtool++ is also a good idea as it is much faster than flvtool2. Still both tools have their problems. More about this in the Comparison of FLV and MP4 metadata tagging tools.