1 files changed, 63 insertions, 0 deletions
diff --git a/parakeet-rs/src/decoder_tdt.rs b/parakeet-rs/src/decoder_tdt.rs
new file mode 100644
index 0000000..65f576d
--- /dev/null
+++ b/parakeet-rs/src/decoder_tdt.rs
@@ -0,0 +1,63 @@
+use crate::decoder::TranscriptionResult;
+use crate::error::Result;
+use crate::vocab::Vocabulary;
+
+/// TDT greedy decoder for Parakeet TDT models
+#[derive(Debug)]
+pub struct ParakeetTDTDecoder {
+    vocab: Vocabulary,
+}
+
+impl ParakeetTDTDecoder {
+    /// Load decoder from vocab file
+    pub fn from_vocab(vocab: Vocabulary) -> Self {
+        Self { vocab }
+    }
+
+    /// Decode tokens with timestamps
+    /// For TDT models, greedy decoding is done in the model, here we just convert to text
+    pub fn decode_with_timestamps(
+        &self,
+        tokens: &[usize],
+        frame_indices: &[usize],
+        _durations: &[usize],
+        hop_length: usize,
+        sample_rate: usize,
+    ) -> Result<TranscriptionResult> {
+        let mut result_tokens = Vec::new();
+        let mut full_text = String::new();
+         // TDT encoder does 8x subsampling
+        let encoder_stride = 8;
+
+        for (i, &token_id) in tokens.iter().enumerate() {
+            if let Some(token_text) = self.vocab.id_to_text(token_id) {
+                let frame = frame_indices[i];
+                let start = (frame * encoder_stride * hop_length) as f32 / sample_rate as f32;
+                let end = if i + 1 < frame_indices.len() {
+                    (frame_indices[i + 1] * encoder_stride * hop_length) as f32 / sample_rate as f32
+                } else {
+                    start + 0.01
+                };
+
+                // Handle SentencePiece format (▁ prefix for word start)
+                let display_text = token_text.replace('▁', " ");
+
+                // Skip special tokens
+                if !(token_text.starts_with('<') && token_text.ends_with('>') && token_text != "<unk>") {
+                    full_text.push_str(&display_text);
+
+                    result_tokens.push(crate::decoder::TimedToken {
+                        text: display_text,
+                        start,
+                        end,
+                    });
+                }
+            }
+        }
+
+        Ok(TranscriptionResult {
+            text: full_text.trim().to_string(),
+            tokens: result_tokens,
+        })
+    }
+}