feat(video): Add VideoTextOverlayBlock

2026-01-21 04:57:58 -05:00 · 2026-01-18 15:33:47 -06:00
parent d0f7ba8cfd
commit c19c3c834a
1 changed files with 135 additions and 0 deletions
--- a/backend/blocks/video/text_overlay.py
+++ b/backend/blocks/video/text_overlay.py
@@ -0,0 +1,135 @@
+"""
+VideoTextOverlayBlock - Add text overlay to video
+"""
+import uuid
+from typing import Literal
+
+from backend.data.block import Block, BlockCategory, BlockOutput
+from backend.data.block import BlockSchemaInput, BlockSchemaOutput
+from backend.data.model import SchemaField
+from backend.util.exceptions import BlockExecutionError
+
+
+class VideoTextOverlayBlock(Block):
+    """Add text overlay/caption to video."""
+
+    class Input(BlockSchemaInput):
+        video_in: str = SchemaField(
+            description="Input video file",
+            json_schema_extra={"format": "file"}
+        )
+        text: str = SchemaField(
+            description="Text to overlay on video"
+        )
+        position: Literal[
+            "top", "center", "bottom",
+            "top-left", "top-right",
+            "bottom-left", "bottom-right"
+        ] = SchemaField(
+            description="Position of text on screen",
+            default="bottom"
+        )
+        start_time: float | None = SchemaField(
+            description="When to show text (seconds). None = entire video",
+            default=None,
+            advanced=True
+        )
+        end_time: float | None = SchemaField(
+            description="When to hide text (seconds). None = until end",
+            default=None,
+            advanced=True
+        )
+        font_size: int = SchemaField(
+            description="Font size",
+            default=48,
+            ge=12,
+            le=200,
+            advanced=True
+        )
+        font_color: str = SchemaField(
+            description="Font color (hex or name)",
+            default="white",
+            advanced=True
+        )
+        bg_color: str | None = SchemaField(
+            description="Background color behind text (None for transparent)",
+            default=None,
+            advanced=True
+        )
+
+    class Output(BlockSchemaOutput):
+        video_out: str = SchemaField(
+            description="Video with text overlay",
+            json_schema_extra={"format": "file"}
+        )
+
+    def __init__(self):
+        super().__init__(
+            id="d4e5f6a7-b8c9-0123-def4-567890123456",
+            description="Add text overlay/caption to video",
+            categories={BlockCategory.MULTIMEDIA},
+            input_schema=self.Input,
+            output_schema=self.Output,
+            test_input={"video_in": "/tmp/test.mp4", "text": "Hello World"},
+            test_output=[("video_out", str)],
+            test_mock={"_add_text": lambda *args: "/tmp/overlay.mp4"}
+        )
+
+    async def run(self, input_data: Input, **kwargs) -> BlockOutput:
+        try:
+            from moviepy.editor import VideoFileClip, TextClip, CompositeVideoClip
+        except ImportError:
+            raise BlockExecutionError(
+                message="moviepy is not installed. Please install it with: pip install moviepy",
+                block_name=self.name,
+                block_id=str(self.id)
+            )
+
+        video = None
+        final = None
+        try:
+            video = VideoFileClip(input_data.video_in)
+
+            txt_clip = TextClip(
+                input_data.text,
+                fontsize=input_data.font_size,
+                color=input_data.font_color,
+                bg_color=input_data.bg_color,
+            )
+
+            # Position mapping
+            pos_map = {
+                "top": ("center", "top"),
+                "center": ("center", "center"),
+                "bottom": ("center", "bottom"),
+                "top-left": ("left", "top"),
+                "top-right": ("right", "top"),
+                "bottom-left": ("left", "bottom"),
+                "bottom-right": ("right", "bottom"),
+            }
+
+            txt_clip = txt_clip.set_position(pos_map[input_data.position])
+
+            # Set timing
+            start = input_data.start_time or 0
+            end = input_data.end_time or video.duration
+            txt_clip = txt_clip.set_start(start).set_end(end)
+
+            final = CompositeVideoClip([video, txt_clip])
+
+            output_path = f"/tmp/overlay_{uuid.uuid4()}.mp4"
+            final.write_videofile(output_path, logger=None)
+
+            yield "video_out", output_path
+
+        except Exception as e:
+            raise BlockExecutionError(
+                message=f"Failed to add text overlay: {e}",
+                block_name=self.name,
+                block_id=str(self.id)
+            )
+        finally:
+            if final:
+                final.close()
+            if video:
+                video.close()