Fix live transcription: use raw PCM extraction instead of soxi

soxi and sox trim rely on the WAV header, which rec does not finalize
until recording stops. This caused the duration check to always return 0,
so no chunks were ever extracted during live recording.

Fix: calculate duration from file size (16kHz * 1ch * 16-bit = 32000 B/s),
extract raw PCM bytes with dd, and convert to WAV with sox for whisper-cli.

Also fix double .txt extension in saved transcript filename.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: maxitoon

whisper-transcribe-with-download.sh

@@ -132,7 +132,7 @@ original_live_transcription() {
     local model_file=$1
     local language=$2
     local recording_file="$AUDIO_DOWNLOAD_DIR/${TIMESTAMP}_live_recording.wav"
-    local transcript_file="$TRANSCRIPT_DIR/${TIMESTAMP}_live_transcript.txt"
+    local transcript_file="$TRANSCRIPT_DIR/${TIMESTAMP}_live_transcript"
 
     print_color "$CYAN" "🎙️  ORIGINAL Live Transcription Setup"
     echo "" >&2
@@ -190,30 +190,38 @@ original_live_transcription() {
     trap cleanup SIGINT SIGTERM
 
     # Incremental chunk-based live transcription
-    local last_transcribed=0
-    local chunk_count=0
+    # rec writes 16kHz mono 16-bit PCM = 32000 bytes/sec
+    # WAV header is not finalized until rec stops, so we calculate
+    # duration from file size and extract raw PCM bytes directly.
+    local BYTES_PER_SEC=32000
+    local WAV_HEADER_SIZE=44
     local MIN_CHUNK_SECS=5
+    local last_byte_offset=$WAV_HEADER_SIZE
+    local chunk_count=0
     local running_transcript="/tmp/running_transcript_${TIMESTAMP}.txt"
     touch "$running_transcript"
 
     while kill -0 $rec_pid 2>/dev/null; do
-        if [ -f "$recording_file" ] && [ -s "$recording_file" ]; then
-            # Get current recording duration in seconds
-            local current_duration
-            current_duration=$(soxi -D "$recording_file" 2>/dev/null || echo "0")
-            # Convert to integer for comparison
-            local current_int=${current_duration%.*}
-            local last_int=${last_transcribed%.*}
-            current_int=${current_int:-0}
-            last_int=${last_int:-0}
-            local new_audio=$((current_int - last_int))
+        if [ -f "$recording_file" ]; then
+            local current_size
+            current_size=$(stat -f%z "$recording_file" 2>/dev/null || echo "0")
+            local new_bytes=$((current_size - last_byte_offset))
+            local new_secs=$((new_bytes / BYTES_PER_SEC))
 
-            if [ "$new_audio" -ge "$MIN_CHUNK_SECS" ]; then
+            if [ "$new_secs" -ge "$MIN_CHUNK_SECS" ]; then
                 chunk_count=$((chunk_count + 1))
 
-                # Extract only the new audio chunk
+                # Align to full seconds of audio
+                local chunk_bytes=$((new_secs * BYTES_PER_SEC))
+                local raw_file="/tmp/chunk_raw_${TIMESTAMP}_${chunk_count}.pcm"
                 local chunk_file="/tmp/chunk_${TIMESTAMP}_${chunk_count}.wav"
-                sox "$recording_file" "$chunk_file" trim "$last_transcribed" 2>/dev/null
+
+                # Extract raw PCM bytes (bypass incomplete WAV header)
+                dd if="$recording_file" of="$raw_file" bs=1 skip="$last_byte_offset" count="$chunk_bytes" 2>/dev/null
+
+                # Convert raw PCM to valid WAV for whisper-cli
+                sox -t raw -r 16000 -c 1 -b 16 -e signed-integer -L "$raw_file" "$chunk_file" 2>/dev/null
+                rm -f "$raw_file"
 
                 if [ -f "$chunk_file" ] && [ -s "$chunk_file" ]; then
                     local chunk_transcript="/tmp/chunk_transcript_${TIMESTAMP}_${chunk_count}"
@@ -225,18 +233,15 @@ original_live_transcription() {
                         local new_text
                         new_text=$(cat "${chunk_transcript}.txt" | sed '/^$/d')
                         if [ -n "$new_text" ] && [ "$new_text" != " " ]; then
-                            # Append to running transcript and display
                             echo "$new_text" >> "$running_transcript"
                             print_color "$GREEN" "$new_text" >&2
                         fi
                     fi
 
-                    # Clean up chunk files
                     rm -f "$chunk_file" "${chunk_transcript}.txt" 2>/dev/null
                 fi
 
-                # Update position to current duration
-                last_transcribed=$current_duration
+                last_byte_offset=$((last_byte_offset + chunk_bytes))
             fi
         fi
         sleep 2