Improve Whisper WASM UI example (#669)

* wip add module and js worker example

* params

* clean up, send error

* final UI with whisper webworker

* add simple instructions

candle-wasm-examples/whisper/src/bin/m.rs

@@ -0,0 +1,41 @@
+use candle_wasm_example_whisper::worker::{Decoder as D, ModelData};
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen]
+pub struct Decoder {
+    decoder: D,
+}
+
+#[wasm_bindgen]
+impl Decoder {
+    #[wasm_bindgen(constructor)]
+    pub fn new(
+        weights: Vec<u8>,
+        tokenizer: Vec<u8>,
+        mel_filters: Vec<u8>,
+    ) -> Result<Decoder, JsError> {
+        let decoder = D::load(ModelData {
+            tokenizer,
+            mel_filters,
+            weights,
+        });
+
+        match decoder {
+            Ok(decoder) => Ok(Self { decoder }),
+            Err(e) => Err(JsError::new(&e.to_string())),
+        }
+    }
+
+    #[wasm_bindgen]
+    pub fn decode(&self, wav_input: Vec<u8>) -> Result<String, JsError> {
+        let segments = self
+            .decoder
+            .convert_and_run(&wav_input)
+            .map_err(|e| JsError::new(&e.to_string()))?;
+
+        let json = serde_json::to_string(&segments)?;
+        Ok(json)
+    }
+}
+
+fn main() {}

candle-wasm-examples/whisper/src/lib.rs

@@ -24,6 +24,6 @@ impl Drop for Timer {
 mod app;
 mod audio;
 mod model;
-mod worker;
+pub mod worker;
 pub use app::App;
 pub use worker::Worker;

candle-wasm-examples/whisper/src/worker.rs

@@ -222,7 +222,7 @@ impl Decoder {
         Ok(segments)
     }
 
-    fn load(md: ModelData) -> anyhow::Result<Self> {
+    pub fn load(md: ModelData) -> anyhow::Result<Self> {
         let device = Device::Cpu;
         let tokenizer = Tokenizer::from_bytes(&md.tokenizer).map_err(anyhow::Error::msg)?;
 
@@ -239,7 +239,7 @@ impl Decoder {
         Ok(decoder)
     }
 
-    fn convert_and_run(&self, wav_input: &[u8]) -> anyhow::Result<Vec<Segment>> {
+    pub fn convert_and_run(&self, wav_input: &[u8]) -> anyhow::Result<Vec<Segment>> {
         let device = Device::Cpu;
         let mut wav_input = std::io::Cursor::new(wav_input);
         let (header, data) = wav::read(&mut wav_input)?;