[Stream] Expanded language support for automated captions (#19562)

* [Stream] Clarify delivery pricing mechanics

* [Stream] Prep announcement for expanded language support for auto-captions

* [Stream] Expanded Language Support

* catastropostrophe

* Update src/content/docs/stream/pricing.mdx

grammar fix

* fix link

---------

Co-authored-by: Denise Peña <[email protected]>

Author: tsmith512

src/content/changelogs-next/2025-01-30-stream-generated-captions-new-languages.mdx

@@ -0,0 +1,25 @@
+---
+title: Expanded language support for Stream AI Generated Captions
+description: Captions can now be generated for 11 additional spoken languages at no cost!
+products:
+  - stream
+date: 2025-01-30T12:00:00Z
+---
+
+Stream's [generated captions](/stream/edit-videos/adding-captions/#generate-a-caption)
+leverage Workers AI to automatically transcribe audio and provide captions to
+the player experience. We have added support for these languages:
+
+- `cs` - Czech
+- `nl` - Dutch
+- `fr` - French
+- `de` - German
+- `it` - Italian
+- `ja` - Japanese
+- `ko` - Korean
+- `pl` - Polish
+- `pt` - Portuguese
+- `ru` - Russian
+- `es` - Spanish
+
+For more information, learn about [adding captions to videos](/stream/edit-videos/adding-captions/).

src/content/changelogs/stream.yaml

@@ -5,6 +5,10 @@ productLink: "/stream/"
 productArea: Developer platform
 productAreaLink: /workers/platform/changelog/platform/
 entries:
+  - publish_date: "2025-01-30"
+    title: Expanded Language Support for Generated Captions
+    description: |-
+      Eleven new languages are now supported for transcription when using [generated captions](/stream/edit-videos/adding-captions/#generate-a-caption), available for free for video stored in Stream.
   - publish_date: "2024-08-15"
     title: Full HD encoding for Portrait Videos
     description: |-

src/content/docs/stream/edit-videos/adding-captions.mdx

@@ -15,7 +15,7 @@ caption file.
 
 To create or modify a caption on a video a [Cloudflare API Token](https://www.cloudflare.com/a/account/my-account) is required.
 
-The `<LANGUAGE_TAG>` must adhere to the [BCP 47 format](http://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers). For convenience, the most common
+The `<LANGUAGE_TAG>` must adhere to the [BCP 47 format](http://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers). For convenience, many common
 language codes are provided [at the bottom of this document](#most-common-language-codes).
 If the language you are adding isn't included in the table, you can find the value
 through the [The IANA registry](https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry), which maintains a list of language codes. To find the
@@ -45,19 +45,34 @@ Generated captions use artificial intelligence based speech-to-text technology
 to generate closed captions for your videos.
 
 A video must be uploaded and in a ready state before captions can be generated.
-In the following example URLs, the video’s UID is referenced as \<VIDEO\_UID>.
+In the following example URLs, the video's UID is referenced as `<VIDEO_UID>`.
 To receive webhooks when a video transitions to ready after upload, follow the
 instructions provided [here](/stream/manage-video-library/using-webhooks/).
 
-Only English language caption generation is currently supported.
+Captions can be generated for the following languages:
 
-Videos may include several language captions, but each language must be unique.
+- `cs` - Czech
+- `nl` - Dutch
+- `en` - English
+- `fr` - French
+- `de` - German
+- `it` - Italian
+- `ja` - Japanese
+- `ko` - Korean
+- `pl` - Polish
+- `pt` - Portuguese
+- `ru` - Russian
+- `es` - Spanish
+
+When generating captions, generate them for the spoken language in the audio.
+
+Videos may include captions for several languages, but each language must be unique.
 For example, a video may have English, French, and German captions associated
 with it, but it cannot have two English captions. If you have already uploaded
 an English language caption for a video, you must first delete it in order to
 create an English generated caption. Instructions on how to delete a caption can be found below.
 
-The \<LANGUAGE\_TAG> must adhere to the BCP 47 format. The tag for English is `en`.
+The `<LANGUAGE_TAG>` must adhere to the BCP 47 format. The tag for English is `en`.
 You may specify a region in the tag, such as `en-GB`, which will render a label
 that shows `British English` for the caption.
 
@@ -171,7 +186,7 @@ https://api.cloudflare.com/client/v4/accounts/<ACCOUNT_ID>/stream/<VIDEO_UID>/ca
 
 ### Example response to get the caption file for a video
 
-```bash
+``` text
 WEBVTT
 
 1

src/content/docs/stream/pricing.mdx

@@ -55,7 +55,7 @@ Delivery is counted by HTTP requests for video segments or parts of the MP4. The
 - Content played from client-side/browser cache is not billable, like a short looping video. Some mobile app player libraries do not cache HLS segments by default.
 - MP4 Downloads are billed by percentage of the file delivered.
 
-HLS and DASH playback is rounded to the segment length. For uploaded content, HLS and DASH segments are four seconds. Live broadcast segments are determined by the keyframe interval or GOP size.
+Minutes delivered for web playback (HLS and DASH) are rounded to the _segment_ length: for uploaded content, segments are four seconds. Live broadcast and recording segments are determined by the keyframe interval or GOP size of the original broadcast.
 
 ## Example scenarios