The purpose of this guide is to provide you with information regarding the files we need from you in order to get your audiobooks onto our store. Each audiobook on the Rakuten Kobo site is made up of five components:
- the audio files of the book itself
- the manifest file
- the metadata file containing information about the audiobook
- a cover image
- an optional sample preview file
Components of a Kobo Audiobook
Audio Files
These are the files containing the tracks of your audiobook. We currently only accept MP3 files. Below are some rules and guidelines to ensure the best user experience for customers listening to your audiobooks on our app:
- Individual MP3 files should be between 200 MB and 800 MB. The maximum size for an MP3 is 2 GB per file.
- There is an upload limit of 1500 audio files. If the number of audio files in your delivery exceeds this limit, your delivery will fail ingestion.
- For bitrate, our system will compress any audio files with a bitrate of 96kbps or more to 64kbps. For this reason, we recommend that you send us the best quality bitrate possible so that there's no loss of quality when the bitrate is then compressed. We recommend a minimum bitrate of 192kbps.
| File Naming Convention | Examples |
| Up to your discretion. Please send file names using Latin characters and numbers only. Please avoid any special characters or the ingestion will fail. |
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Manifest
The manifest is an essential part of your audiobook delivery, and must be delivered along with your audio files. It serves 2 purposes:
- Assures Kobo that your audio delivery is complete and removes the need for file naming conventions.
- It allows you, the publisher, to provide Kobo customers and devices with a table of contents to navigate through the audiobook. This way, you can provide customers with an experience that closely mirrors that of a print book or eBook.
There are 2 ways for you to provide this asset to us: JSON or Excel.
| File Naming Convention | Examples |
| Up to your discretion but needs to contain the word “manifest” |
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The maximum size for a manifest is 5 MB per file.
Option 1: JSON Manifest
In the JSON Manifest, there are 3 top-level fields: the manifest version (“manifest_version”), the list of files (“file_list”), and the table of contents (“table_of_contents”). Samples for JSON manifests can be found here:
The following breaks down the components of the JSON manifest.
Manifest Version: The version of the manifest you are using. This allows us to evolve the manifest overtime, while remaining backwards compatible.
File_list: The list of files associated with a product. Each entry should have:
| Field | Definition | Examples |
| duration | The duration of the file in seconds. This allows us to flag any discrepancies, since the audiobook will fail to be processed in our system if the duration provided in the manifest does not match the actual audio duration of the product.(We do allow for a 1 second discrepancy, but anything over that will fail.) Please note that this piece is optional. If you choose not to include the duration, please remove this field from the JSON to prevent failure. |
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| media_type | The MIME type of the audio file. This should be consistent for a single product. We currently support either audio/mpeg or audio/m4a for this piece. |
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| file_name | The file name that you have assigned to the file. Please make sure that you input the exact name of the mp3 file, otherwise it will fail to be processed. |
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| file_order_id | The order in which the file should appear in the audiobook, with the first file starting at 0. |
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Table_of_contents: This element is how you can provide the user-facing chapter names. Each entry should have:
| Field | Definition | Examples |
| title | The name of the chapter or track, as it should appear to the customer. This should be in the same language as the audiobook. If you do not have chapter names, we recommend using “Track 1”, “Track 2”, etc. If your chapter extends beyond 1 MP3 file, please designate the second file as part 2 of the previous chapter. |
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| file_order_id | The order in which the file should appear in the audiobook, with the first file starting at 0. This should match the file_order_id assigned to it in the “file_list”. |
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| offset | If not 0, the number of seconds into the file the chapter starts at. |
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NOTE: the JSON manifest should NOT include your sample preview file. Your sample preview file is delivered separately (see section "Sample Preview File" below) and is not part of the manifest.
Option 2: Excel Manifest
If you are not familiar with JSON files and would like to choose a different delivery method, you can send an Excel file instead. This option supports audiobook delivery in any case where 1 file is equal to 1 chapter and table of contents entry. You can download the Excel manifest template HERE. (Note: please don't modify the formatting of the template as this may cause the file to fail ingestion in our system.)
The following breaks down the components of the Excel manifest.
| Column A | Contains all the audio files that make up the product. Include here the full name of the files, including the extension. |
| Column B | The name of each file, as you would like it to appear in the Table of Contents. If a chapter spans two files, you can designate a second file as part 2 of the previous chapter, e.g., Chapter 1: Part 2. |
| Column C | Please note that this piece is optional. The duration of the file in seconds. This allows us to flag any discrepancies, since the audiobook will fail to be processed in our system if the duration provided in the manifest does not match the actual audio duration of the product. However, if you choose to not include the duration, please keep the “Duration” header included in the original template. Any changes to these headers will result in the failure of the Excel manifest file. |
NOTE: the Excel manifest should NOT include your sample preview file. Your sample preview file is delivered separately (see section "Sample Preview File" below) and is not part of the manifest.
Metadata
Along with your audiobook and manifest files, information about each of your audiobooks must be sent to us in a metadata file. This should contain everything that makes your audiobook sellable on the Kobo store - from the title, author, and description to prices, sales rights, and publication dates. We prefer to handle metadata in the industry-standard ONIX format, but we can also send you an Excel template if you’re unfamiliar with ONIX. You can look up our best practices for audiobooks metadata here.
Cover Image
The cover image of your audiobook. We request that you send square-shaped covers. Our preference is to provide the highest quality available, and preferably with 1:1 aspect ratio. If square-shaped images are not provided, our system will add letterboxing or slightly skew the image to fit industry standard. We accept JPG or PNG files for cover images.
| File Naming Convention | Example |
| Must be named by the title’s 13-digit ISBN |
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Sample Preview File
You have the option of providing a sample audio file, which provides customers with a way to preview your product on our website and in our apps.
We highly encourage you to provide a customized audio sample for your title, as it allows you to choose the parts of your audiobook that you'd like to highlight in the sample. However, if you don't provide a customized sample for your title, our system will automatically create a sample for your audiobook based on either the first 5 minutes of the title or the first 5% of the title (whichever value is smallest).
Please note that if your title is 5 minutes long or less, we will not be automatically generating a sample preview for it.
Note: samples will not appear on the product page until the title is officially for sale. So for audiobooks that are on preorder, there will be no sample available on our site.
| File Naming Convention | Example |
| Should include the word “sample” or “preview” |
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Upload Process
FTP Access
To deliver your audiobook assets, you will require access to an FTP client. We recommend Filezilla if you don’t already have a preferred client yourself.
In your onboarding email, you will find the login details for your SFTP (Secure File Transfer Protocol) account. The following outlines how each asset should be uploaded. Please note that everything should be dropped directly into the /incoming folder icon. Anything dropped outside this folder will not be ingested in our system
Audio Files and Manifest Delivery
Your audio files and manifest must be contained within the same folder. This ensures that your files and manifest are delivered at the same time. If they are not delivered at the same time, within the same folder, it will fail to be processed in our system.
In addition, this folder must be named by the audiobook’s 13-digit ISBN.
Metadata, Cover Images, and Sample Preview File Delivery
Unlike your audio files and manifest, the metadata, cover images, and sample preview should not be included within the 13-digit ISBN folder. Please refer to “Components of a Kobo Audiobook” for file naming conventions.
Finished Product
In the end, your uploaded assets should look like this in the FTP:
File Size Limitations
The maximum size for the entire audiobook package (audio files + manifest) is 10 GB.
Please note that due to the large-size of audiobooks, we request that you send no more than 60GB of files per day. Any deliveries larger than that can slow down ingestion across all of our accounts. For any large delivery of files exceeding 60 GB, please deliver your titles in batches.