Widevine updates#

Widevine is a system addon allowing Firefox users to read DRM’d content (like Netflix). We provide updates via Balrog.


The request comes from the media team. They usually file a bug like this one.

Sometimes updates must be done because Google (the owner of Widevine) deprecates a version that still may be used by a supported Firefox version (e.g.: Firefox ESR).


Ensure what Firefox version is able to run the new version#


There are 2 types of patches the Media team makes:

  1. The actual patch to make Firefox compatible with the new API (for example: bug 1420836). This kind of patch must happen before the balrog rule is set.

  2. Another patch that updates the fallback downloader (like bug 1479579). This kind of patch can be landed after the balrog rule is set

Take a look at Widevine version numbers to determine whether Firefox needs to be updated.

Old schema (< 1.4.9.X)#

For instance:






It has always been 1, so far



Significant changes must happen on the Firefox side



If this number changes, some Firefox internals must be changed

10 88


This number keeps increasing even if the other numbers got bumped

If the API level (or higher) is bumped, please check with the Media team what Firefox is able to run this Widevine.

New schema (> 1.4.9.x)#

For instance: TBD





See old schema


See old schema


See old schema



Create the blob#

Unlike Firefox, no automation creates a blob. Nor do we have a script (patch welcome!) to generate one. Therefore we need to create a new blob based on the most recent release. You can view existing releases at https://balrog.services.mozilla.com/releases. Then download the most recent blob: e.g.Widevine-4.10.2391.0. and open the downloaded blob in an editor. It’s small and should be like:

  "hashFunction": "sha512",
  "name": "Widevine-4.10.2391.0",
  "product": "Widevine",
  "schema_version": 1000,
  "vendors": {
    "gmp-widevinecdm": {
      "platforms": {
        "Darwin_aarch64-gcc3": {
          "fileUrl": "https://redirector.gvt1.com/edgedl/widevine-cdm/4.10.2391.0-mac-arm64.zip",
          "filesize": 6511203,
          "hashValue": "041a9bbe89160f604d72db92fc9c1fdce75d528706245c837d4d0ea71e96c1b5106e512ca37e075373ceaeda64e6dd42e02889edaee8dc3077718620a16b4f2e"
        "Darwin_x86_64-gcc3": {
          "alias": "Darwin_x86_64-gcc3-u-i386-x86_64"
        "Darwin_x86_64-gcc3-u-i386-x86_64": {
          "fileUrl": "https://redirector.gvt1.com/edgedl/widevine-cdm/4.10.2391.0-mac-x64.zip",
          "filesize": 6942023,
          "hashValue": "2cf195a99dd13019c2f29e036f98e10905d1472f013970bd8b2f0ff65fe2b20a9058570c57b3595c1b9824326ac11a185a80008d618c673736323355345d69fe"
        "Linux_x86_64-gcc3": {
          "fileUrl": "https://redirector.gvt1.com/edgedl/widevine-cdm/4.10.2391.0-linux-x64.zip",
          "filesize": 6328796,
          "hashValue": "8ce16faae96274e1f5ec63f6f543fa33ab3b7d469e59fac2d8b45cb27d3c95820cf80cd362d6e972a1c3c27e5c1b28c018fbdc2bb7df50f095391a646e277a99"
        "Linux_x86_64-gcc3-asan": {
          "alias": "Linux_x86_64-gcc3"
        "WINNT_aarch64-msvc-aarch64": {
          "alias": "WINNT_x86-msvc"
        "WINNT_x86-msvc": {
          "fileUrl": "https://redirector.gvt1.com/edgedl/widevine-cdm/4.10.2391.0-win-ia32.zip",
          "filesize": 6331242,
          "hashValue": "24569de210f6a6d47daf0e64441f0c575dcbb23e5ff2fcb705edcd6e0fce9378caafd84e81a1c0efd25056a686ab8cb47855f43230ee37ddabc97453b72024ff"
        "WINNT_x86-msvc-x64": {
          "alias": "WINNT_x86-msvc"
        "WINNT_x86-msvc-x86": {
          "alias": "WINNT_x86-msvc"
        "WINNT_x86_64-msvc": {
          "fileUrl": "https://redirector.gvt1.com/edgedl/widevine-cdm/4.10.2391.0-win-x64.zip",
          "filesize": 6537814,
          "hashValue": "81b2329d38a9370afc490db805a05c4b506b113ebd00f4e488bca97fd96267d92cb477e3a635880464ca66ed32f448e46ad3645f6af072547b5f09100db2bf74"
        "WINNT_x86_64-msvc-x64": {
          "alias": "WINNT_x86_64-msvc"
        "WINNT_x86_64-msvc-x64-asan": {
          "alias": "WINNT_x86_64-msvc"
      "version": "4.10.2391.0"

From the above, edit the name and version to match the new version. Then under each platform, update the hashValue, filesize, and fileUrl based on the values provided to you in the widevine tracking bug. e.g. bug 1801201. (Recently, the media team has kindly provided the blob definition in the bug – all the better!) Save the new blob as a .json file.

Create the Balrog release#

Create a new release and upload the new blob to Balrog:
  • on https://balrog.services.mozilla.com/releases click the “Add new release” button;

  • on the Create Release page, select “Widevine” as the Product;

  • on the Create Release page, click “Upload Release” and select the file containing the new release blob;

  • verify that the new release blob has been uploaded and the “Release” name correctly identifies the release (eg. “Widevine-4.10.2391.0”);

  • on the Create Release page, click “Create Release” button in the lower right to create the release.

Create the Balrog rule#

Create a new rule to use the release you just created:
  • on https://balrog.services.mozilla.com/rules click the “Add Rule” button

  • on the Create Rule page, set Product = “Widevine”, Channel = “nightlytest” (or as specified in the bug), Mapping = the release you just created, Background Rate = 100 (or as specified in the bug), and set the Priority as needed, typically just a little higher than the priority for the default rule.

  • on the Create Rule page, click “Create Rule” button in the lower right to create the rule.

Deployment usually proceeds in a series of steps over several days. Usually the Media team requests initial deployment to only the nightlytest channel, then the nightlytest and nightly channels, then also the beta channel, etc. To implement this (assuming an existing default Widevine rule with priority 420):

  • create a rule for nightlytest with priority 425

  • when requested to add nightly, create a new rule for the nightly channel with priority 425

  • when requested to add beta, create a new rule for beta with priority 425

  • when requested to add esr, create a new rule for esr* with priority 425

  • when requested to make the new CDM the default, update the default rule’s release, then delete the other rules (nightlytest, nightly, beta, esr*).

See this page for general guidance on rule matching.

Unlike Firefox updates, Widevine ones all happen in the same channel (except for the nightlytest, the internal testing channel). This means users are given a new widevine based on their Firefox version. For instance: if we provide a new widevine to 98.0 at the time 98.0b15 ships, then users with 98.0b1-b14 will also get this version. Make sure with the media team these betas are compatible! In the case it’s not, please remember Firefox doesn’t send which beta it’s on to Balrog. You have to filter out based on the version and the buildID (the buildID alone doesn’t work if a 97 dot release happens afterwards).

In the end, a rule that filters on both looks like this one: Balrog rule


You can use the nightlytest channel to test changes before sending them to production. A widevine request to balrog is like this one: https://aus5.mozilla.org/update/3/GMP/98.0/20180802174131/WINNT_x86_64-msvc-x64/en-US/nightlytest/default/default/default/update.xml


Reminder: In this URL, 98.0 can’t be 98.0b14. Even though it works from Balrog’s point of view, Firefox doesn’t send this piece of data.