add support for NVIDIA llm (#1645)

### What problem does this PR solve?

add support for NVIDIA llm
### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>

rag/llm/cv_model.py

@@ -137,7 +137,6 @@ class Base(ABC):
         ]
 
 
-
 class GptV4(Base):
     def __init__(self, key, model_name="gpt-4-vision-preview", lang="Chinese", base_url="https://api.openai.com/v1"):
         if not base_url: base_url="https://api.openai.com/v1"
@@ -619,3 +618,65 @@ class LocalCV(Base):
 
     def describe(self, image, max_tokens=1024):
         return "", 0
+
+
+class NvidiaCV(Base):
+    def __init__(
+        self,
+        key,
+        model_name,
+        lang="Chinese",
+        base_url="https://ai.api.nvidia.com/v1/vlm",
+    ):
+        if not base_url:
+            base_url = ("https://ai.api.nvidia.com/v1/vlm",)
+        self.lang = lang
+        factory, llm_name = model_name.split("/")
+        if factory != "liuhaotian":
+            self.base_url = os.path.join(base_url, factory, llm_name)
+        else:
+            self.base_url = os.path.join(
+                base_url, "community", llm_name.replace("-v1.6", "16")
+            )
+        self.key = key
+
+    def describe(self, image, max_tokens=1024):
+        b64 = self.image2base64(image)
+        response = requests.post(
+            url=self.base_url,
+            headers={
+                "accept": "application/json",
+                "content-type": "application/json",
+                "Authorization": f"Bearer {self.key}",
+            },
+            json={
+                "messages": self.prompt(b64),
+                "max_tokens": max_tokens,
+            },
+        )
+        response = response.json()
+        return (
+            response["choices"][0]["message"]["content"].strip(),
+            response["usage"]["total_tokens"],
+        )
+
+    def prompt(self, b64):
+        return [
+            {
+                "role": "user",
+                "content": (
+                    "请用中文详细描述一下图中的内容，比如时间，地点，人物，事情，人物心情等，如果有数据请提取出数据。"
+                    if self.lang.lower() == "chinese"
+                    else "Please describe the content of this picture, like where, when, who, what happen. If it has number data, please extract them out."
+                )
+                + f' <img src="data:image/jpeg;base64,{b64}"/>',
+            }
+        ]
+
+    def chat_prompt(self, text, b64):
+        return [
+            {
+                "role": "user",
+                "content": text + f' <img src="data:image/jpeg;base64,{b64}"/>',
+            }
+        ]