Fallback to non worker tfjs when on Safari (#193)

Safari's worker limitations mean that detection threads in the worker barely function. Until Apple quits being whiny jerks about PWAs, this workaround is required to bypass the message calls to the workers and use the old single threaded system when Safari is detected.

Reviewed-on: #193

src/assets/detect-worker.js

@@ -57,7 +57,7 @@ async function loadModel(weights, preload) {
 }
 
 async function localDetect(imageData) {
-  console.time('pre-process')
+  console.time('sw: pre-process')
   const [modelWidth, modelHeight] = model.inputs[0].shape.slice(1, 3)
   let gTense = null
   const input = tf.tidy(() => {
@@ -65,15 +65,15 @@ async function localDetect(imageData) {
     return tf.concat([gTense,gTense,gTense],3)
   })
   tf.dispose(gTense)
-  console.timeEnd('pre-process')
+  console.timeEnd('sw: pre-process')
 
-  console.time('run prediction')
+  console.time('sw: run prediction')
   const res = model.predict(input)
   const tRes = tf.transpose(res,[0,2,1])
   const rawRes = tRes.arraySync()[0]
-  console.timeEnd('run prediction')
+  console.timeEnd('sw: run prediction')
 
-  console.time('post-process')
+  console.time('sw: post-process')
   const outputSize = res.shape[1]
   let rawBoxes = []
   let rawScores = []
@@ -138,14 +138,14 @@ async function localDetect(imageData) {
   }
   tf.dispose(res)
   tf.dispose(input)
-  console.timeEnd('post-process')
+  console.timeEnd('sw: post-process')
 
   return output || { detections: [] }
 }
 
 async function videoFrame (vidData) {
   const [modelWidth, modelHeight] = model.inputs[0].shape.slice(1, 3)
-  console.time('frame-process')
+  console.time('sw: frame-process')
   let rawCoords = []
   try {
     const input = tf.tidy(() => {
@@ -171,6 +171,6 @@ async function videoFrame (vidData) {
   } catch (e) {
     console.log(e)
   }
-  console.timeEnd('frame-process')
+  console.timeEnd('sw: frame-process')
   return {cds: rawCoords, mW: modelWidth, mH: modelHeight}
 }