In this article
The short answer
- OpenAI is an easy place to start if you mainly listen to major languages such as English or Japanese and want straightforward time-based pricing.
- Gemini offers a broader choice when you need more than 70 languages and regional language variants.
- The official effective rates are $0.034 per minute for OpenAI and about $0.0368 per minute for Gemini. Confirm the final bill in the provider console.
- Gemini 3.5 Live Translate is a Preview model, so test long-session stability with your own content before using it for important work.
Start with the models actually used for translation
This is not a general chatbot comparison. As of August 2026, kkamagi connects to OpenAI gpt-realtime-translate and Google gemini-3.5-live-translate-preview. Both behave more like interpretation pipelines that turn incoming speech into translated audio and text than general assistants that answer questions.
| Item | OpenAI | Gemini |
|---|---|---|
| Model | gpt-realtime-translate | gemini-3.5-live-translate-preview |
| Primary output | Translated audio and text deltas | Translated audio plus input and output transcripts |
| kkamagi input | 24 kHz mono PCM16 | 16 kHz mono PCM16 |
| Model status | Dedicated Realtime Translation model | Preview model |
Languages: OpenAI for 13 major outputs, Gemini for breadth
kkamagi exposes 13 OpenAI output languages: Korean, English, Japanese, Chinese, Spanish, Portuguese, French, German, Italian, Russian, Hindi, Indonesian, and Vietnamese. That covers most common English-video and Japanese-event listening needs for Korean users.
- Choose OpenAI first when you repeatedly listen to English, Japanese, Chinese, and major European languages.
- Choose Gemini first when researchers or marketers move between conferences and interviews from many countries.
- Gemini also separates variants such as Simplified and Traditional Chinese and Brazilian and European Portuguese.
Google states that Gemini Live Translation supports more than 70 languages. Listed support does not guarantee equal quality for every accent, dialect, or technical domain. Test low-resource languages and mixed-language audio with representative content.
Cost: monthly listening time matters more than a small rate gap
OpenAI lists gpt-realtime-translate at $0.034 per minute of audio. Google's pricing combines about $0.0053 per minute for input audio and $0.0315 per minute for output audio, for an effective rate of roughly $0.0368 per minute.
| Interpretation time | OpenAI | Gemini |
|---|---|---|
| 1 hour | $2.04 | About $2.21 |
| 5 hours | $10.20 | About $11.04 |
| 10 hours | $20.40 | About $22.08 |
| 30 hours | $61.20 | About $66.24 |
Compare quality with the same segments of the same audio
Real-time interpretation behaves differently with a single-speaker lecture, an interrupt-heavy podcast, music-heavy video, or a technical presentation. Your own recurring content is more useful than a one-off demo.
- Pick five minutes each from the introduction, a fast section, and a technical section.
- Record first-audio delay and whether sentence endings are clipped.
- Check numbers, negation, and names of people, companies, and products.
- Compare original-to-translation balance and fatigue after at least 15 minutes.
- Note stalls, duplicated audio, and reconnects at the end.
For important meetings, verify numbers, contractual terms, dates, and negative statements against the original audio, chat, or official minutes. AI interpretation helps comprehension; it is not certified interpretation or a legal record.
Privacy: separate app storage from provider processing
kkamagi uses a bring-your-own-key model. API keys are stored in macOS Keychain and original or translated audio is not saved as an audio file. While interpretation is on, capturable system audio may still be sent to the selected external provider.
- Stored locally by kkamagi: provider settings, translation history, and usage estimates
- Not saved as files by kkamagi: original and translated audio
- Check separately: data use and retention policies for each OpenAI or Google account type
Recommendations by scenario
| Scenario | Start with | Why |
|---|---|---|
| English or Japanese YouTube | OpenAI | Major languages are covered and per-minute cost is simple |
| Research across many countries | Gemini | More than 70 languages and finer output-language choices |
| Long daily listening | A/B test both | Stability and actual billing matter more at scale |
| Important business meeting | Prepare a fallback | High error cost requires original and official-record verification |
Start with OpenAI when major languages, simple hourly cost, and less Preview risk matter most. Start with Gemini when broad language coverage is essential. A practical setup is to run a 15-minute comparison, keep one provider as the default, and retain the other as a fallback.
Frequently asked questions
Do I need both OpenAI and Gemini API keys?
No. One key is enough if you use only one provider. Both are useful for comparison and failover.
Does ChatGPT Plus or a Google AI subscription include API use?
Consumer subscriptions and developer API billing are generally separate. Check billing and credits in each API console.
Does broader language support mean better translation quality?
No. It expands choice, while actual quality still varies with pronunciation, accent, audio quality, terminology, and overlapping speech.
Can I use real-time interpretation as meeting minutes?
It is not recommended. Important records should be checked against the source and reviewed by a person, especially numbers and proper nouns.
Official sources
Choose by real listening results, not language count alone
Neither provider wins every scenario. Compare the same 15 minutes of your usual content and choose a default based on delay, meaning preservation, listening fatigue, and long-session stability.
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