Live subtitles (public preview)

ApsaraVideo Live provides live subtitles that use real-time speech recognition to convert live stream audio into subtitles with translation support for Chinese, English, Spanish, and Russian.

Usage notes

Supported regions are listed in Regions.
Live subtitles is in public preview. Each user can create up to 300 subtitle templates. One template can be associated with multiple subtitle rules.
A subtitle template defines subtitle properties such as content and layout, but does not specify a streaming domain or AppName.
After you create a subtitle template, create a subtitle rule that references it. In the rule, specify a streaming domain and an AppName that matches the AppName in the ingest URL. Restart stream ingest for subtitles to take effect.
Live subtitles is a paid service, free during public preview. Standard billing applies after the preview ends. You will be notified of the billing start date in advance.

Procedure

Step 1: Add a subtitle template

Console

Log on to the ApsaraVideo Live console.
In the navigation pane on the left, choose Feature Management > Real-time Subtitles. On the Real-time Subtitles page, select the Subtitle Templates tab.
Select the region for the subtitle template, and then click Add Subtitle Template to configure it.

Preview subtitle effects in the preview area by adjusting the video resolution, subtitle size, and position. The following table describes the subtitle template parameters.

Parameter	Description
Creation method	Create New Subtitle Template: Create a custom subtitle template from scratch. Copy Existing Subtitle Template: Select an existing subtitle template to copy its parameters and quickly create a new template.
Subtitle template name	The template name. Can contain digits, letters, and hyphens (-). Cannot start with a hyphen.
Template description	Up to 128 characters, including Chinese characters, letters, digits, and symbols.
Source language	Supported languages: Chinese, English, and Russian.
Translation	Valid values: Chinese, English, Spanish, Russian, and No Translation. If you select Chinese, English, Spanish, or Russian as the target language, you can choose whether to display the source language. If you select No Translation, the source language must be displayed.
Maximum lines	Maximum lines to display. Valid values: 1 to 300.
Max characters per line	Maximum characters per line. Valid values: 10 to 320.
Font	Subtitle font. Valid values: KaiTi Alibaba PuHuiTi-Regular Alibaba PuHuiTi-Bold Alibaba PuHuiTi-Light Source Han Sans-Regular Source Han Sans-Bold Source Han Sans-Light
Font size	The font size for subtitles.
Subtitle background	If enabled, you can set the background color and opacity. If disabled, the background is hidden.
Color settings	Set the color and opacity of the subtitles and their background.
Resolution (width × height)	Preview resolution. Valid values: Landscape LD (360p) 640×360 Portrait LD (360p) 360×640 Landscape SD (480p) 854×480 Portrait SD (480p) 480×854 Landscape HD (720p) 1280×720 Portrait HD (720p) 720×1280 Landscape FHD (1080p) 1920×1080 Portrait FHD (1080p) 1080×1920

Click Submit to complete the configuration.
After the template is added, a dialog box prompts you to add a subtitle rule. Click Add to add a rule for this template, or click Later to skip.

On the Subtitle Templates tab, find the template that you want to manage. In the Actions column, you can click Preview, Modify, or Delete.

Actions	Description
Preview	Preview subtitle effects.
Modify	Edit the template parameters.
Delete	On the subtitle template list, if the Bound Subtitle Rules column shows 0, the template has no bound rules. Click Delete to delete it. If a template is bound to subtitle rules (Bound Subtitle Rules is not 0), the Delete button is disabled. Delete the bound rules first. Click the number in the Bound Subtitle Rules column to view them.
Add Subtitle Rule	Add a subtitle rule for this template. Step 2: Add a subtitle rule.

Note

Template changes do not affect active streams. Restart stream ingest to apply changes.

API

Use the following API operations to manage subtitle templates.

API	Reference
AddLiveAISubtitle	Add a live subtitle template
DeleteLiveAISubtitle	Delete a subtitle template
UpdateLiveAISubtitle	Update a subtitle template
DescribeLiveAISubtitle	Query subtitle templates

Step 2: Add a subtitle rule

Console

Log on to the ApsaraVideo Live console.
In the navigation pane on the left, choose Feature Management > Real-time Subtitles. On the Real-time Subtitles page, select the Subtitle Rules tab.
Select the region for the subtitle rule. Only domains and templates within that region are available. Then, click Add Subtitle Rule.

The following table describes the subtitle rule parameters.

Parameter	Description
Rule description	Up to 128 characters. Can contain Chinese characters, letters, digits, and symbols.
Streaming domain	Select the primary streaming domain for this rule.
AppName	The application name for the stream. Must match the AppName in the ingest URL for the subtitle template to take effect. Up to 256 characters: digits, letters, hyphens (-), and underscores (_).
Subtitle template	Select a subtitle template. If none exists, create one first. Step 1: Add a subtitle template.
Output settings	For best results, match the output resolution with the resolution set in the subtitle template. Supported output resolutions: Landscape LD (360p) 640×360 Portrait LD (360p) 360×640 Landscape SD (480p) 854×480 Portrait SD (480p) 480×854 Landscape HD (720p) 1280×720 Portrait HD (720p) 720×1280 Landscape Full HD 1080p 1920x1080 Portrait FHD (1080p) 1080×1920
Triggered by stream pulling	Controls when the subtitled stream is generated. Enabled: Subtitles are generated only when viewers are pulling the stream. Generation stops after 5 minutes of no stream pulling and resumes when pulling restarts. Disabled: Subtitles are generated whenever stream ingest is active, regardless of viewer activity.

Click Submit to complete the rule configuration.

Note
Restart stream ingest after configuring a subtitle rule for subtitles to appear in the stream.
On the Subtitle Rules tab, find the rule you want to manage. In the Actions column, click Preview, Edit, or Delete.
- Preview: Preview subtitle effects.
- Edit: Edit the rule parameters.
- Delete: Delete the subtitle rule.

API

Use the following API operations to manage subtitle rules.

API	Reference
AddLiveAIProduceRules	Add a live subtitle rule
UpdateLiveAIProduceRules	Update a live subtitle rule
DescribeLiveAIProduceRules	Query subtitle rules
DeleteLiveAIProduceRules	Delete a subtitle rule

Step 3: Ingest a live stream

Generate an ingest URL by using the console URL generator or by constructing it manually. Generate ingest and streaming URLs.

Step 4: Play the subtitled stream

To play the subtitled stream, append _{subtitle_template_name} to the StreamName in the playback URL.

RTMP: rtmp://example.aliyundoc.com/app/stream_{subtitle_template_name}?auth_key={access_token}
FLV: http://example.aliyundoc.com/app/stream_{subtitle_template_name}.flv?auth_key={access_token}
M3U8: http://example.aliyundoc.com/app/stream_{subtitle_template_name}.m3u8?auth_key={access_token}

Note

Subtitled streams do not support the ARTC protocol.