Show HN: Kling 3.0 video generation with native audio synthesis

Hi HN,

  I've been testing Kling 3.0 (Kuaishou's latest video generation model) and wanted to share what makes it technically interesting.

  **Key technical features:**

  1. Native audio-visual synchronization - The model generates audio that syncs with video content during generation, not
  post-processing. This is different from adding stock music after the fact.

  2. Start-end frame interpolation (I2V mode) - You can provide both a starting and ending frame, and the model interpolates motion
  between them. Useful for controlled transitions.

  3. Flexible temporal control - 3-15 second generation with 13 granular duration options.

  **Technical implementation on our platform (FreyaVideo):**

  - Cost calculation based on duration + audio flag (duration_audio mode)
  - Async job processing through FAL API
  - Credit-based pricing to handle variable generation costs

  **Limitations:**

  - Generation time: 60-120 seconds
  - 1080p max resolution
  - Audio quality varies depending on prompt specificity
  - Higher cost with audio enabled ($0.252/sec vs $0.168/sec from FAL)

  The audio generation is genuinely novel - I haven't seen other models (Sora, Veo, Runway) do this natively. Happy to answer 
  technical questions about integration or model behavior.

  ---

  **Tech stack:** Next.js, PostgreSQL, FAL API integration
  **Pricing:** Credit-based, configurable via JSON config in database