New element to parse Chinese AVS video streams

Submitted by Aurélien Zanelli

Link to original bug (#741868)

Description

Created attachment 293191
Chinese AVS video extract

I would like to propose a new element to parse Chinese AVS video stream, obviously named 'cavsvideoparse' :)

It is built against gst-plugins-bad codecparsers/videoparsers.

Currently, it only knows Jizhun profile, which is the only one supported by libav decoder iirc.
For parse element, I currently use video/x-gst-av-cavs as media type to be compatible with the current one of gst-libav. But I propose to define a shorter media-type like video/x-cavs if you are agree with that.

At this moment, this element is not complete as some features are missing (timestamping...) and still quite simple but it is usable and enables raw AVS byte stream to be played.

For an exemple of use, I attached an extract of AVS video stream which has been cutted quickly with 'dd' and which can be played with the following pipeline:
gst-launch-1.0 filesrc location=test.avs ! cavsvideoparse ! video/x-gst-av-cavs,stream-format=unit-frame ! avdec_cavs ! autovideosink

Attachment 293191, "Chinese AVS video extract":
test.avs