byted-tos-video-process（字节跳动 tos 视频流程）

Bytedance TOS Video Process Skill

This skill provides essential video processing functions for video files stored in Bytedance's TOS (TeraObjectStore). It allows you to retrieve video metadata and perform single-frame or multi-frame snapshots directly using the Volcengine TOS SDK.

Quick Start

1. Client Initialization

The following Python snippet demonstrates how to initialize the TosClientV2 from environment variables.

import os
import tos
from tos.exceptions import TosClientError, TosServerError

def create_client() -> tos.TosClientV2:
    """Initializes a TosClientV2 using AK/SK (and optional STS token) from environment variables."""
    try:
        ak = os.getenv('TOS_ACCESS_KEY')
        sk = os.getenv('TOS_SECRET_KEY')
        endpoint = os.getenv('TOS_ENDPOINT')
        region = os.getenv('TOS_REGION')
        security_token = os.getenv('TOS_SECURITY_TOKEN') # Optional, for STS

        if not all([ak, sk, endpoint, region]):
            raise ValueError("Required environment variables are missing (AK, SK, Endpoint, Region).")

        return tos.TosClientV2(
            ak=ak,
            sk=sk,
            endpoint=endpoint,
            region=region,
            security_token=security_token,
        )
    except (ValueError, ImportError) as e:
        print(f"Error initializing client: {e}")
        # Handle initialization failure
        return None

# Create the client
client = create_client()

2. Basic Workflow

# (Assumes 'client' is initialized and 'bucket_name', 'object_key' are set)

# 1. Get Video Info
try:
    response = client.get_object(bucket_name, object_key, process="video/info")
    info_data = response.read()
    print("Video Info:", info_data.decode('utf-8'))
except TosServerError as e:
    print(f"Error getting video info: {e}")

# 2. Take a Single Snapshot and save locally
try:
    client.get_object_to_file(
        bucket_name,
        object_key,
        "snapshot_1000ms.jpg",
        process="video/snapshot,t_1000,f_jpg,w_720"
    )
    print("Snapshot saved to snapshot_1000ms.jpg")
except TosServerError as e:
    print(f"Error taking snapshot: {e}")

# 3. Take a Snapshot and save back to TOS
try:
    response = client.get_object(
        bucket_name,
        object_key,
        process="video/snapshot,t_5000,f_jpg",
        save_bucket=bucket_name,
        save_object="processed/snapshot_5000ms.jpg"
    )
    save_result = response.read()
    print("Snapshot saved to TOS:", save_result.decode('utf-8'))
except TosServerError as e:
    print(f"Error saving snapshot to TOS: {e}")

Core Operations

All video processing is achieved via the process parameter in the get_object or get_object_to_file SDK methods.

1. Get Video Info (videoInfo)

Retrieves metadata of a video file, such as resolution, duration, and format.

SDK Method: client.get_object(..., process="video/info")

# 'client', 'bucket_name', and 'object_key' must be defined
try:
    response = client.get_object(bucket_name, object_key, process="video/info")
    # The response body is a JSON string
    video_metadata = response.read().decode('utf-8')
    print(video_metadata)
except TosServerError as e:
    print(f"Server Error: {e.code} - {e.message}")

2. Take a Single Snapshot (videoSnapshot)

Captures a single frame from a video. It supports various parameters for customization and can either return the image data or save the result directly back to TOS.

SDK Method: client.get_object_to_file(..., process="video/snapshot,...") for local save. SDK Method: client.get_object(..., process="video/snapshot,...", save_bucket=..., save_object=...) for saving to TOS.

# Example: Take a snapshot at 10 seconds, resize to 720p width, and save locally
try:
    client.get_object_to_file(
        bucket_name,
        object_key,
        file_path="local_snapshot.jpg",
        process="video/snapshot,t_10000,w_720,f_jpg"
    )
    print("Snapshot saved successfully to local_snapshot.jpg")
except (TosClientError, TosServerError) as e:
    print(f"An error occurred: {e}")

3. Take Multiple Snapshots (videoSnapshots)

This is a client-side orchestration pattern. You loop through a series of timestamps and make multiple calls to the videoSnapshot operation. The scripts/video_snapshots.py provides a reference implementation for parallel execution.

# (Assumes 'client', 'bucket_name', 'object_key' are set)
timestamps = [1000, 5000, 10000]  # In milliseconds

for i, ts in enumerate(timestamps):
    output_filename = f'snapshot_{i+1}_at_{ts}ms.jpg'
    process_rule = f"video/snapshot,t_{ts},w_720,f_jpg"
    try:
        client.get_object_to_file(
            bucket_name,
            object_key,
            output_filename,
            process=process_rule
        )
        print(f"Saved snapshot to {output_filename}")
    except (TosClientError, TosServerError) as e:
        print(f"Failed for timestamp {ts}: {e}")

Authorization

Authentication is handled directly by the tos.TosClientV2 constructor. Provide credentials via environment variables.

Required Environment Variables

• TOS_ACCESS_KEY: Your Access Key ID.
• TOS_SECRET_KEY: Your Secret Access Key.
• TOS_ENDPOINT: The endpoint for the TOS service (e.g., https://tos-cn-beijing.volces.com).
• TOS_REGION: The region for the TOS service (e.g., cn-beijing).

Optional for STS

• TOS_SECURITY_TOKEN: If using a temporary token (STS), provide the session token here. The client will automatically use it if present.

Best Practices

• Error Handling: Always wrap SDK calls in try...except blocks to handle TosClientError and TosServerError.
• Parameter Validation: Validate parameters like time, width, and height on the client side before making an API call to prevent unnecessary errors.
• Batch Operations: For videoSnapshots, use a thread pool (like ThreadPoolExecutor) to perform multiple snapshot requests in parallel for better performance. See scripts/video_snapshots.py for an example.
• Credentials Management: Use a secure method to manage and refresh credentials, especially when using short-lived STS tokens.

Additional Resources

• For detailed parameters of each operation, see REFERENCE.md.
• For common end-to-end examples, see WORKFLOWS.md.
• For executable Python examples, see the scripts/ directory.