Package limn.video.decode

package limn.video.decode

Decoders, and the pooling every decoder needs. The toolkit's limn.video publishes what a picture is and how a source is driven; this is where implementations of that live, so that a codec dependency has somewhere to land that is not a module everything else depends on.

Install what an application wants and open through the facade:

 Videos.installDecoder(new Y4mDecoder());
 Videos.installDecoder(new SyntheticVideoDecoder());
 try (VideoStreamSource source = Videos.open(file)) {
     while (source.readFrame() == VideoStreamSource.Read.FRAME) {
         VideoFrame frame = source.frame();
         // ... upload it, draw it ...
         frame.release();
     }
 }
 

The application installs decoders, not the backend. Which decoders exist is an application's decision (it is what it ships and what it is licensed for), and the install order is the probe order, so a backend that installed its own would silently take priority over the application's.

Both decoders here are pure Java with no dependency of any kind, which is why they are the ones that came first: a Y4M file proves the seam against real bytes somebody else's tool wrote, and a synthetic stream proves it against arithmetic, with no codec, no native and no committed media in either direction.

Related Packages

Package	Description
limn.video	Backend-neutral video: a pooled VideoFrame of planar YCbCr samples described by a PixelFormat layout and a VideoColor interpretation, produced by a VideoStreamSource that a VideoDecoder opened through the Videos facade, timed by VideoClock and shown by uploading it to a VideoSurface that the VideoSurfaces facade created, or, where no device conversion exists, turned into RGBA by YuvConverter.
limn.video.ffmpeg	H.264 and AAC out of MP4, through a trimmed FFmpeg behind a hand-written JNI shim.

Class	Description
FramePool	A fixed set of pictures a decoder fills and hands out, and the free list that takes them back.
SyntheticPattern	What a synthetic stream draws.
SyntheticSpec	The whole description of a synthetic stream: what it draws, how big, in which layout, under which colour interpretation, how fast, for how long, and how many pictures it keeps in flight.
SyntheticVideoDecoder	A decoder with nothing to decode: it draws its pictures, so a video is available on any machine, in every layout, under every colour interpretation and at any size, with no file to ship and nothing to go missing.
Y4mDecoder	Reads YUV4MPEG2: a text header, then a FRAME line and raw planes per picture, with no compression and no container.
Y4mWriter	Writes what a source produces as a YUV4MPEG2 file: the counterpart that makes Y4mDecoder verifiable, and the only way to get a real video file out of this project without shipping one.