Snapshot Capturing

Process Flow

Figure 1 shows the process for configuring a snapshot template.

Figure 1 Process for configuring a snapshot template

1. (Optional) Create an OBS bucket for storing live video snapshots. If you already have one, go to 2.
   

   The OBS bucket for storing live video snapshots must be in the same region as the Live service. For example, if you use Live in the CN North-Beijing4 region, then snapshots must be stored in an OBS bucket in the CN North-Beijing4 region.

2. Authorize access to the OBS bucket so that the system can save the snapshots in the OBS bucket.
3. Configure a snapshot template to capture snapshots from a video stream at a specified interval and save them as JPG files in an authorized OBS bucket.
4. View snapshots in the output path.

Notes

• The region where the Live service is located must be the same as the OBS bucket for storing snapshots.
• Only JPG files can be generated.
• In the AP-Bangkok region, submit a service ticket for review after configuring a template. The configuration takes effect only after it is approved.

Prerequisites

• Domain names have been added.
• CNAME records have been added to your domains' DNS records.
• Snapshots are stored in OBS. Therefore, you must enable OBS before storing snapshots in OBS. For details, see OBS Getting Started Guide.

Pricing Notes

• Snapshot capturing is a billing item. You are billed based on the number of snapshots. For details, see Live Pricing Details.
• Snapshots are stored in OBS. Therefore, OBS charges you for the storage. For details, see OBS Pricing Details.

Step 1: (Optional) Create an OBS Bucket

If you have not created an OBS bucket, create one in the same region as Live by referring to Creating a Bucket. If you already have one, go to Step 2: Authorize Access to the OBS Bucket.

Step 2: Authorize Access to the OBS Bucket

Perform the following steps to authorize Live to store snapshots in your OBS bucket.

After access to the OBS bucket is authorized, Live can access the OBS bucket. Ensure that the bucket processes only workloads related to Live. Do not store confidential files in the bucket.

1. Log in to the Live console.
2. In the navigation pane, choose Authorization.
3. On the OBS Authorization tab, click Authorize in the Operation column of the row containing the target OBS bucket.
   Figure 2 OBS authorization
   

Step 3: Configure a Snapshot Template

After OBS authorization is successful, you can configure a snapshot template.

1. Log in to the Live console.
2. In the navigation pane, choose Domains.
3. Click Manage in the Operation column of the desired ingest domain name.
4. In the navigation pane, choose Template > Snapshot.
5. Click Create Snapshot Template.
   Figure 3 Creating a snapshot template
   

   Table 1 describes the parameters.

   Table 1 Template parameters

   Parameter	Description
   AppName	Application name. The default value is live. You can customize the application name. Only letters, digits, underscores (_), and hyphens (-) are allowed.
   Storage Bucket	OBS bucket for storing snapshots
   Storage Path	OBS storage path
   Screenshot Frequency	The unit is second. Value range: 5 to 3600
   Storage Mode	The value can be Full storage or Instant storage. Full storage: All snapshot files are stored. A snapshot file is named as follows: {domain}/{app_name}/{stream_name}/{UTCTimestamp}.jpg Instant storage: Only the latest snapshot is saved. A snapshot file is named as follows: {domain}/{app_name}/{stream_name}.jpg
   Callback	Whether to enable callback
   Callback URL	Enter a callback URL when Callback is enabled. A callback URL cannot contain message headers or parameters. HTTP and HTTPS are supported. HTTPS is recommended. Callback messages in JSON format are sent in POST requests to your server through HTTP APIs. For details about a callback message body, see Callback Message.
   Authentication Key	Authentication key. If callback authentication is required, set this parameter. Otherwise, leave it empty. A key contains 32 to 128 characters. A key can also be automatically generated.

6. Click OK.

   After a snapshot template is configured, stream push starts. During stream push, the system takes snapshots of the live stream based on template settings.

7. Click Edit in the Operation column to modify template parameters. AppName cannot be modified.

Step 4: View Snapshots

View the snapshots in the predefined output path or from a download link in your received callback message.

• Viewing the snapshots on the console
  1. Log in to the Live console.
  2. In the navigation pane, choose Domains.
  3. Click Manage in the Operation column of the desired ingest domain name.
  4. In the navigation pane, choose Template > Snapshot.
  5. Click the output path in the Storage Location column to go to the OBS bucket and view snapshot details.
     Figure 4 Viewing snapshot details
     

     You can download and share the snapshots. For details, see OBS Help Center.

• Viewing snapshots through a callback message

  If you set a callback URL when configuring a snapshot template, then you will receive a message each time a snapshot is generated. Table 2 describes the fields in a callback message.

  { 
      "domain": "play.example.com",
      "app": "live",
      "stream_name": "test001",
      "snapshot_url": "https://xxx.obs.cn-north-4.myhuaweicloud.com:443...",
      "width":"720",
      "height":"1280",
      "obs_addr": {
          "bucket": "xxx",
          "location": "cn-north-4",
          "object": "xxx.jpg"
      },
     "auth_timestamp":1587954140,
      "auth_sign":"4918b1axxxxxxb583cffa119d72513bbc35a989f8569fxxxxxx057646154a04a"
  }

  Table 2 Message body

  Field	Description
  domain	Ingest domain name
  app	Application name
  stream_name	Stream name
  snapshot_url	URL to download snapshots
  width	Image width Unit: pixel
  height	Image height Unit: pixel
  obs_addr	Address of the OBS bucket where snapshots are stored. bucket: OBS bucket name location: Region where the OBS bucket is located object: OBS object path
  auth_timestamp	UNIX timestamp when the event notification signature expires. This parameter is carried when an authentication key is configured. The value is a decimal UNIX timestamp, that is, the number of seconds that have elapsed since January 1, 1970 (midnight UTC/GMT). Example: 1592639100 (June 20, 2020 15:45)
  auth_sign	Event notification signature. This parameter is carried when an authentication key is configured. auth_sign = HmacSHA256(domain + app + stream_name + snapshot_url + width + height + obs_addr.bucket + obs_addr.location + obs_addr.object + auth_timestamp,key) key indicates the key used for authentication.