Add audio

Add an audio track to a video. This one can be tricky if both video and audio don't have the same length.

POST /add-audio
Content-Type: application/json

{
  "videoFileId": "string",
  "audioFileId": "string",
  "outputFormat": "mp4" | "mkv" | "webm" | "mov" | "avi",
  "mode": "replace" | "append"
}

Technical Details:

• Smart codec selection based on output format:
  • MP4/MOV: AAC (192kbps) or copy if compatible
  • WebM: Opus (128kbps) or copy if compatible
  • MKV: Supports multiple codecs, defaults to AAC
  • AVI: MP3 or WAV
• Uses -shortest flag to match video duration
• Preserves video quality with -c:v copy