Add video caption upload documentation and improve error message

fixes #2038

server/middlewares/validators/videos/video-captions.ts

@@ -2,7 +2,7 @@ import * as express from 'express'
 import { areValidationErrors } from '../utils'
 import { isIdOrUUIDValid } from '../../../helpers/custom-validators/misc'
 import { body, param } from 'express-validator'
-import { CONSTRAINTS_FIELDS } from '../../../initializers/constants'
+import { CONSTRAINTS_FIELDS, MIMETYPES } from '../../../initializers/constants'
 import { UserRight } from '../../../../shared'
 import { logger } from '../../../helpers/logger'
 import { isVideoCaptionFile, isVideoCaptionLanguageValid } from '../../../helpers/custom-validators/video-captions'
@@ -13,9 +13,9 @@ const addVideoCaptionValidator = [
   param('videoId').custom(isIdOrUUIDValid).not().isEmpty().withMessage('Should have a valid video id'),
   param('captionLanguage').custom(isVideoCaptionLanguageValid).not().isEmpty().withMessage('Should have a valid caption language'),
   body('captionfile')
-    .custom((value, { req }) => isVideoCaptionFile(req.files, 'captionfile')).withMessage(
-    'This caption file is not supported or too large. Please, make sure it is of the following type : '
-    + CONSTRAINTS_FIELDS.VIDEO_CAPTIONS.CAPTION_FILE.EXTNAME.join(', ')
+    .custom((_, { req }) => isVideoCaptionFile(req.files, 'captionfile')).withMessage(
+    `This caption file is not supported or too large. Please, make sure it is under ${CONSTRAINTS_FIELDS.VIDEO_CAPTIONS.CAPTION_FILE.FILE_SIZE} and one of the following mimetypes: `
+    + Object.keys(MIMETYPES.VIDEO_CAPTIONS.MIMETYPE_EXT).map(key => `${key} (${MIMETYPES.VIDEO_CAPTIONS.MIMETYPE_EXT[key]})`).join(', ')
   ),
 
   async (req: express.Request, res: express.Response, next: express.NextFunction) => {

support/doc/api/openapi.yaml

@@ -1292,7 +1292,7 @@ paths:
                   format: binary
             encoding:
               captionfile:
-                contentType: text/vtt, application/x-subrip
+                contentType: text/vtt, application/x-subrip, text/plain
       responses:
         '204':
           $ref: '#/paths/~1users~1me/put/responses/204'