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    Live Subtitling

    Last updated: 2024-09-18 16:00:53
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      The live subtitling feature can perform real-time Automatic Speech Recognition (ASR) in live streaming, convert the speech into subtitles, and support translation into the target language. Currently, the feature offers multilingual speech translation services. In practical applications, choose appropriate target language combinations based on your service needs and audiences.
      This document describes how to create, modify, and delete subtitle templates through the console.

      Points of Attention

      A template takes effect about 5 to 10 minutes after successfully created.
      To use the live subtitling function, after binding a subtitle template to a transcoding template, you should obtain the subtitle stream with the suffix of a playback address corresponding to the name of a transcoding template.
      Live subtitling function is a premium service. Utilizing this function will incur live transcoding fees and ASR fees of MPS. Cross-language translation may generate voice translation fees of MPS. For the specific billing rules, please refer to billing document.

      Prerequisites for Use

      The CSS service has been activated.

      Creating Subtitle Template

      1. Log in to the CSS console. Choose Feature Configuration > Live Subtitles.
      Note:
      Due to the use of the live subtitling function, creating a service role and authorizing the current account role to use MPS product services are required for the first creation of a subtitle template.
      2. Click Grant access to enter the CAM role management page.
      
      3. On the role management page, click Grant. After completing identity authentication to finish the MPS authorization, you can utilize the MPS service normally.
      
      
      4. After successful authorization, select the service agreement and click Start. The system will automatically activate the MPS product and open the live subtitling management page.
      5. Click Create template to enter the subtitle template creation page and configure the template as follows:
      
      Note:
      The font selection for subtitles will vary depending on the Audio and Video Language, Target language, and Subtitles you select. Please select the appropriate type according to your actual needs.
      Configuration Item
      Description
      Template Name
      The prefix for the template name is fixed to "subtitle". The template name cannot exceed 30 characters and only supports English letters and digits.
      Template Description
      Subtitle template description. It contains up to 100 characters, only supporting letters, digits, underscores, and dashes.
      Dynamic/Steady State Effect
      The default setting is delayed steady-state sentence-by-sentence subtitles. You can switch it to real-time dynamic subtitles or delayed steady-state word-by-word subtitles.
      When choosing the Delayed Steady State Subtitles mode, it's necessary to set the latency, with a default value of 10 seconds. Available latency options include 20 seconds, 30 seconds, and 60 seconds.
      Note:
      When you choose real-time dynamic subtitles, subtitles in live streaming will be dynamically corrected word by word based on changes in speech. When you choose delayed steady-state word-by-word subtitles, the system will delay the display of live streaming based on the set time, but the full-sentence subtitle mode provides a better viewing experience.
      Source language
      The default language is Chinese, and English, Japanese, and Korean are also supported.
      Target language
      It is set to None by default. Switching to any of the three other options not selected in the source language is supported. For instance, if English is selected as the source language, the available options for the target language include No Selection, Chinese, and Japanese, Korean.
      Cross-language translation will incur voice translation fees of MPS. ASR fees will be generated without translation. For more details, please see Content II.
      If you need to translate it into other languages, please submit a ticket to contact us.
      Subtitles
      Source is supported by default. Target and Source + target are also supported.
      By choosing the Source language , Target language , and Subtitles options, you can achieve subtitle effects in different languages.
      ASR Associating with Custom Hotwords
      The feature of ASR associating with custom hotwords is disabled by default and can be manually enabled based on your service needs.
      After enabling the feature of custom hotword lexicons, you need to select the hotword lexicon you want to apply. If you have not created a hotword lexicon, you can click Add to jump to the Create Hotword Lexicon page. For detailed steps, see Creating Library.
      
      Preset styles
      The default option is Small text without bar. You may select Small text without bar, Large text without bar, Small text with bar, or Large text with bar to configure the settings.
      Once selected, the system will automatically set the corresponding subtitle style, which can be manually modified.
      Modifying the configuration will clear the preset style selection status.
      Font
      The font selection for subtitles will vary depending on the Source language, Target language, and Subtitles you select.
      You may choose a variety of fonts such as DIN Alternate Bold, Helvetica, or HelveticalnseratLTPro-Roman, or select a custom font according to your service needs.
      If you need a custom font, click Custom to upload the font. The system will display a confirmation box. Before uploading and using the font, check the notice, and then click OK . Note that only .ttf files are supported. Before using a custom font, make sure that you have obtained legal authorization, otherwise Tencent Cloud will not bear any legal responsibility arising from the use.
      When the Original Text + Translated Subtitles mode is selected, the default font for both source and target is Heiti. If the subtitles displayed are in English, the "Helvetica" font can be chosen.
      Lines
      Options are 1 or 2, with 1 selected by default.
      When lines exceed the displayed range, only the latest content will be displayed.
      Characters per line
      Value range: 1-100. Default value: 45. One Chinese character count as one word. One English character or number counts as half a word. The fewer the characters per line are, the larger the font size is.
      
      Color
      The default font color is black. The color can be customized.
      The default background color is black. The customization of level of transparency is supported.
      Preview
      You can preview the subtitle effects configured in the current template. The subtitle effects are only for reference. The content is not translated.
      In the preview window, you can adjust the size and position of the subtitle block by dragging it.
      Horizontal elongation or shortening: You can adjust the width of the subtitle block by dragging its edge horizontally. This will adjust the value of the horizontal distance simultaneously.
      Dragging upwards or downwards as a whole: You can change the position of the subtitle block on the screen by dragging it. This will adjust the value of the vertical distance simultaneously.
      Preview window size
      Set the subtitle preview window size:
      Default values for width and height: 1920px for width and 1080px for height.
      Value range for width and height: 360px - 4096px.
      If you need to modify the size of the preview window, you can enter new width and height values. After inputting the new width and height values, click Update ; the size of the preview window will change proportionally. You can set the most suitable preview window size according to your needs and screen size.
      Line spacing
      The vertical distance percentage represents the ratio of the vertical distance to the vertical width of the subtitles from the bottom of the screen. The vertical position of the subtitles is configured by adjusting the vertical distance percentage.
      Value range: 0 - 100%.
      Margins
      The horizontal distance percentage represents the ratio of the horizontal distance to the horizontal width of the subtitles and the side of the screen. The horizontal position of the subtitles is configured by adjusting the horizontal distance percentage.
      Value range: 0 - 50%.
      Test subtitle
      Entering the subtitle test content is to add new subtitles to videos for previewing the subtitle effects.
      6. Click Save to save the current template.

      Binding Transcoding Template

      1. Log in to the CSS console. Choose Feature Configuration > Live Subtitles.
      2. The system allows subtitle templates to bind transcoding templates or adaptive bitrate templates. Both transcoding templates and adaptive bitrate templates have similar subsequent use procedures. A transcoding template serves as an example for description below:
      2.1 Direct association with transcoding templates:
      2.1.1 Associate a transcoding template after it is successfully created: After the successful creation of a transcoding template, click Bind transcoding template in the upper left corner.
      
      2.1.2 Select Transcoding template or Adaptive bitrate template according to your actual business requirements, then click Confirm.
      
      2.2 In order to bind a playback domain to the corresponding transcoding template, the subtitle effects will be output at the same time when the transcoding stream is obtained subsequently (add _ transcoding template name after the corresponding live stream StreamName to generate a transcoding stream address).
      Note:
      Once the transcoding template is bound, the subtitle function configured in the transcoding template will be synchronously activated.

      Unbinding

      1. Log in to the CSS console. Choose Feature Configuration > Live Subtitles.
      2. Select the transcoding template associated with a domain name and click Unbind.
      
      3. Confirm whether to unbind the current associated domain. Click Confirm to unbind it.
      

      Modifying a Template

      1. Log in to the CSS console. Choose Feature Configuration > Live Subtitles.
      2. Select the successfully created subtitle template and click Edit on the right to go to the template information modification page. Click Save to finish the modification.
      

      Deleting a Template

      Note:
      If the template has already been associated, you must first unbind it before you proceed with the deletion process.
      Note that a template cannot be restored after deleted. Be careful when performing operations.
      1. Log in to the CSS console. Choose Feature Configuration > Live Subtitles.
      2. Select the successfully created subtitle template and click Delete above.
      
      3. Confirm whether to delete the current subtitle template, then click Confirm to successfully delete it.
      
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