Decode Dirac video using the <video> tag

Dirac is the BBC's wavelet codec. The signal is a raw elementary stream - a chain of parse units, each opening with a 13-byte "BBCD" header - decoded here by libschro_1, on top of schroedinger, and re-encoded to MP4 by libx264_1 with isobmff_1 for the <video> element. Note what this does not cover: schroedinger predates VC-2's high-quality profile, which is what today's VC-2 encoders emit, and would decode those pictures into a uniform grey - so the filter refuses them rather than pretending. This clip is Dirac core syntax, inter-coded.

Code snippet

<video is="universal-video_1" src="testcard.drc" using="solver_1"
        with="libschro_1;isobmff_1;libx264_1" controls> </video>

Specifications :

The specifications of the test sequence are :