Translate a Pre-Recorded Audio File

#!/usr/bin/env bash
set -euo pipefail

AUTH_KEY="YOUR_AUTH_KEY"
FILE="podcast-episode-42.mp3"
FILE_SIZE=$(wc -c < "$FILE")
API_BASE="https://api.deepl.com"  # DeepL API Free users: use https://api-free.deepl.com

# Step 1: Create the job
# curl uses -sf so that any non-2xx HTTP response is treated as an error and
# causes the script to exit immediately via set -e. If the job creation fails
# (e.g. invalid auth key or malformed request), the script stops here and
# curl prints the HTTP status to stderr.
echo "Creating job..."
RESPONSE=$(curl -sf -X POST "$API_BASE/v1/jobs/voice/translate" \
  -H "Authorization: DeepL-Auth-Key $AUTH_KEY" \
  -H "Content-Type: application/json" \
  -d "{
    \"source_file\": {
      \"name\": \"$FILE\",
      \"content_type\": \"audio/mpeg\",
      \"content_length\": $FILE_SIZE
    },
    \"parameters\": { \"source_language\": \"en\" },
    \"targets\": [
      { \"language\": \"de\", \"type\": \"text/plain\" },
      { \"language\": \"es\", \"type\": \"audio/pcm;encoding=s16le;rate=16000\" }
    ]
  }")

JOB_ID=$(echo "$RESPONSE" | jq -r '.job_id')
UPLOAD_URL=$(echo "$RESPONSE" | jq -r '.upload_url')
echo "Job ID: $JOB_ID"

# Step 2: Upload the file
# Same -sf behaviour as above: a non-2xx response from the storage endpoint
# (e.g. expired upload URL or size mismatch) exits the script immediately.
echo "Uploading $FILE..."
curl -sf -X PUT "$UPLOAD_URL" \
  -H "Content-Type: audio/mpeg" \
  --data-binary @"$FILE"
echo "Upload complete."

# Step 3: Poll for status
# Note: -f is intentionally omitted from the polling curl. Transient errors
# such as 429 (rate limit) or 503 (service unavailable) are realistic during
# polling. Without -f, curl returns the response body so the script can log
# the error and retry on the next loop iteration rather than exiting silently.
echo "Polling for results..."
while true; do
  STATUS=$(curl -s "$API_BASE/v1/jobs/voice/translate/$JOB_ID" \
    -H "Authorization: DeepL-Auth-Key $AUTH_KEY") || { echo "Poll failed — check your auth key and job ID"; exit 1; }

  RESULTS=$(echo "$STATUS" | jq '.results')
  ALL_DONE=true

  for i in $(echo "$RESULTS" | jq 'keys[]'); do
    TARGET_STATUS=$(echo "$RESULTS" | jq -r ".[$i].status")
    if [[ "$TARGET_STATUS" == "processing" || "$TARGET_STATUS" == "pending" || "$TARGET_STATUS" == "uploaded" ]]; then
      ALL_DONE=false
    fi
  done

  echo "$STATUS" | jq '.results | map({status, error: .error.message})'

  if $ALL_DONE; then
    break
  fi

  sleep 5
done

# Step 4: Download completed results
# Derive language and extension from the job status response so that this loop
# stays correct even if the targets array order changes or additional targets
# are added in Step 1.
NUM_TARGETS=$(echo "$STATUS" | jq '.results | length')

for i in $(seq 0 $((NUM_TARGETS - 1))); do
  TARGET_STATUS=$(echo "$STATUS" | jq -r ".results[$i].status")

  # Read language and type from the targets array in the status response
  LANG=$(echo "$STATUS" | jq -r ".targets[$i].language")
  CONTENT_TYPE=$(echo "$STATUS" | jq -r ".targets[$i].type")

  # Derive a file extension from the declared content type
  if [[ "$CONTENT_TYPE" == text/* ]]; then
    EXT="txt"
  elif [[ "$CONTENT_TYPE" == audio/pcm* ]]; then
    EXT="pcm"
  else
    # Fallback: use the subtype portion of the content type
    EXT=$(echo "$CONTENT_TYPE" | cut -d'/' -f2 | cut -d';' -f1)
  fi

  if [[ "$TARGET_STATUS" == "complete" ]]; then
    DOWNLOAD_URL=$(echo "$STATUS" | jq -r ".results[$i].download_url")
    OUTPUT="output-$LANG.$EXT"
    echo "Downloading $LANG result to $OUTPUT..."
    curl -sf -o "$OUTPUT" "$DOWNLOAD_URL"
    echo "Saved $OUTPUT."
  else
    echo "Target $LANG finished with status: $TARGET_STATUS"
  fi
done