Chris@8: 
Chris@93: module yetilab.stream.framer;
Chris@8: 
Chris@25: /**
Chris@25:  * Framer expresses a stream (or a file) as a lazy list of (possibly
Chris@25:  * overlapping) frames of mono data.
Chris@25:  */
Chris@25: 
Chris@93: block = load yetilab.block.block;
Chris@93: bf = load yetilab.block.blockfuncs;
Chris@93: af = load yetilab.stream.audiofile;
Chris@93: win = load yetilab.transform.window;
Chris@93: fft = load yetilab.transform.fft;
Chris@8: 
Chris@32: blockList framesize stream =
Chris@14:     if stream.finished? then
Chris@14:        (stream.close (); [] );
Chris@13:     else
Chris@32:         block.resizedTo framesize (stream.readMono framesize)
Chris@32:             :. \(blockList framesize stream);
Chris@13:     fi;
Chris@13: 
Chris@47: overlappingBlockList size hop stream valid buffer =
Chris@29:    (
Chris@29:     b = stream.readMono hop;
Chris@24:     obtained = block.length b;
Chris@23: 
Chris@32:     // Retain framesize - hop samples from old buffer, add hop samples
Chris@29:     // (zero-padded if necessary) just read
Chris@47:     buffer = block.concat
Chris@47:        [block.rangeOf buffer hop (size-hop),
Chris@47:         block.resizedTo hop b];
Chris@23: 
Chris@23:     // Number of "valid" elements (not tail-end zero-padding) left in buffer
Chris@24:     remaining = valid - (hop - obtained);
Chris@23: 
Chris@23:     if remaining <= 0 then
Chris@23:         stream.close ();
Chris@23:         [];
Chris@12:     else
Chris@47:         buffer :. \(overlappingBlockList size hop stream remaining buffer);
Chris@23:     fi);
Chris@14: 
Chris@32: frames { framesize, hop } stream =
Chris@32:     if framesize == hop then
Chris@32:         blockList framesize stream
Chris@30:     else
Chris@32:         overlappingBlockList framesize hop stream 
Chris@47:             framesize (block.zeros framesize);
Chris@30:     fi;
Chris@14: 
Chris@49: windowedFrames { framesize, hop, window } stream =
Chris@49:    (win = window framesize;
Chris@49:     map (bf.multiply win) (frames { framesize, hop } stream));
Chris@49: 
Chris@49: frequencyDomainFrames { framesize, hop } stream =
Chris@49:    (f = fft.realForward framesize;
Chris@49:     map f (windowedFrames { framesize, hop, window = win.hann } stream));
Chris@23: 
Chris@11: { 
Chris@30:     frames,
Chris@49:     windowedFrames,
Chris@49:     frequencyDomainFrames,
Chris@49: 
Chris@49:     framesOfFile parameters filename =
Chris@81:         case af.open filename of
Chris@81:         Stream s: Frames (frames parameters s);
Chris@81:         Error e: Error e;
Chris@81:         esac,
Chris@49: 
Chris@49:     windowedFramesOfFile parameters filename = 
Chris@81:         case af.open filename of
Chris@81:         Stream s: Frames (windowedFrames parameters s);
Chris@81:         Error e: Error e;
Chris@81:         esac,
Chris@49: 
Chris@49:     frequencyDomainFramesOfFile parameters filename = 
Chris@81:         case af.open filename of
Chris@81:         Stream s: Frames (frequencyDomainFrames parameters s);
Chris@81:         Error e: Error e;
Chris@81:         esac,
Chris@11: }
Chris@8: