Editing DirectShow (section)

===Codec hell===
Codec hell (a term derived from [[DLL hell]]) is when multiple DirectShow filters conflict for performing the same task. A large number of companies now develop codecs in the form of DirectShow filters, resulting in the presence of several filters that can decode the same media type.<ref>{{cite web|url=http://www.homevideo101.com/codec-hell/|title=Codec Hell|work=HomeVideo101 Blog|date=2007-06-22|access-date=2010-08-18|url-status=dead|archive-url=https://web.archive.org/web/20120211125026/http://www.homevideo101.com/codec-hell/|archive-date=2012-02-11}}</ref><ref name="Arms Race">{{cite web |url=http://msmvps.com/blogs/chrisl/archive/2005/01/27/34039.aspx#34071 |title=New Age DLL Hell? Hell Yes |author=Lanier, Chris |work=Chris Lanier's Blog |publisher=MSMVPS.COM |date=2005-01-27 |access-date=2007-02-27 |url-status=dead |archive-url=https://web.archive.org/web/20070212213535/http://msmvps.com/blogs/chrisl/archive/2005/01/27/34039.aspx#34071 |archive-date=2007-02-12 }}</ref> This issue is further exacerbated by DirectShow's merit system, where filter implementations end up competing with one another by registering themselves with increasingly elevated priority.<ref name="Arms Race"/>

Microsoft's Ted Youmans explained that "DirectShow was based on the merit system, with the idea being that, using a combination of the filter’s merit and how specific the media type/sub type is, one could reasonably pick the right codec every time. It wasn't really designed for a competing merit nuclear arms race."<ref name="Arms Race"/>

A tool to help in the troubleshooting of "codec hell" issues usually referenced is the GSpot Codec Information Appliance, which can be useful in determining what codec is used to render video files in [[Audio Video Interleave|AVI]] and other containers.<ref>{{cite web|url=http://www.headbands.com/gspot/|title=The GSpot Codec Information Appliance|access-date=2010-08-18}}</ref> [[GraphEdit]] can also help understanding the sequence of filters that DirectShow is using to render the media file. Codec hell can be resolved by manually building filter graphs, using a media player that supports ignoring or overriding filter merits, or by using a filter manager that changes filter merits in the [[Windows Registry]].<ref name="GraphEdit"/>