| The avi decoder plugins |
| ----------------------- |
| |
| The avi decoder consists of a set of gstreamer plugins: |
| |
| - demuxer (avidemux) |
| - avi to gstreamer type converter (avitypes) |
| - windows dlls wrappers. |
| |
| the avidecoder element uses the above plugins to perform the avi |
| decoding. It is constructed as a custom bin which initially only has |
| the demuxer element in it. The demuxer has a set of padtemplates for |
| raw audio and video. |
| |
| (------------------------------------) |
| ! avidecoder ! |
| ! (video/raw)... |
| ! (----------) ! |
| ! ! demuxer (video/x-msvideo, auds).. |
| ! ! ! ! |
| ! -src ! ! |
| ! / ! (video/x-msvideo, vids).. |
| - src ! ! ! |
| ! (----------) (audio/raw)... |
| ! ! |
| (------------------------------------) |
| |
| the demuxer has a set of padtemplates for the raw avi header properties. |
| |
| The avi decoder will act on the new_pad signal of the demuxer element |
| and will attach an avitype plugin to the new pad. Caps negotiation will |
| convert the raw avi caps to the gstreamer caps. If the src pad of the |
| avitypes plugin are compatible with the avidecoder padtemplate, the |
| avitype pad is ghosted to the avidecoder bin, this is the case where no |
| codec is needed (for raw PCM samples, for example). |
| |
| When the avitypes caps are not compatible with one of the avidecoder |
| templates, a static autoplugger is used the find an element to connect |
| the demuxers pad to the decoders padtemplate. |
| |
| When no element could be found, an windec plugin is attached to the |
| demuxers pad and the avitypes plugin is removed from the decoder. |
| |
| |
| example: |
| -------- |
| |
| An avidecoder that has a video pad (decoded with windows dlls) and an |
| audio pad (raw PCM). |
| |
| (----------------------------------------------------------------) |
| ! avidecoder (--------) (------) ! |
| ! !avitypes! !windec! /-- (video/raw) |
| ! (----------) /-sink src--sink src ----- ! |
| ! !demuxer (video/x-msvideo, ! ! ! ! |
| ! ! ! auds).. (--------) (------) ! |
| ! -sink ! (--------) ! |
| ! / ! (video/x-..,!avitypes! ! |
| -sink ! ! vids).. ! ! ! |
| ! (----------) \-sink src -------------------- (audio/raw) |
| ! (--------) ! |
| (----------------------------------------------------------------) |
| |
| |
| |
| TODO |
| ---- |
| |
| automatically generate the padtemplates from all possible avi types |
| found in the registry. |
| |
| |
