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feat(dash): Construct ClearKey PSSH based on MPD ContentProtection #4104

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merged 3 commits into from
Apr 13, 2022
Merged

feat(dash): Construct ClearKey PSSH based on MPD ContentProtection #4104

merged 3 commits into from
Apr 13, 2022

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sr1990
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@sr1990 sr1990 commented Apr 8, 2022 •
edited by joeyparrish
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This PR parses default_KID from ContentProtection in the manifest and constructs a PSSH box from it to feed to the ClearKey CDM only if clear key content is detected.

Example:

<ContentProtection
    schemeIdUri="urn:mpeg:dash:mp4protection:2011" value="cenc"
    cenc:default_KID="9eb4050d-e44b-4802-932e-27d75083e266" />
<ContentProtection
    value="ClearKey1.0" schemeIdUri="urn:uuid:e2719d58-a985-b3c9-781a-b030af78d30e">
         <clearkey:Laurl Lic_type="EME-1.0">https://drm-clearkey-testvectors.axtest.net/AcquireLicense</clearkey:Laurl>
 </ContentProtection>

PSSH is based on https://www.w3.org/TR/eme-initdata-cenc/

Tested content:
https://media.axprod.net/TestVectors/v7-MultiDRM-SingleKey/Manifest_1080p_ClearKey.mpd

joeyparrish
joeyparrish requested changes Apr 12, 2022
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lib/util/pssh.js Outdated
@@ -124,6 +124,49 @@ shaka.util.Pssh = class {
return psshBox;
}

/**
* Creates a ClearKey cenc pssh blob from the given system ID and data.
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In fact, this only creates a ClearKey PSSH blob if the system ID is right. It seems more that what this method does is create a v1 PSSH.

It's confusing, though, because you treat "data" as a single key ID, and leave the "data" payload of the PSSH box empty.

There are very few differences between this method and createPssh. If you add version and key ID parameters to createPssh, you could make that method support v1 PSSHs. Then, you could make a convenience method for ClearKey that provides the correct system ID, an empty data field, and passes along a list of key IDs.

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Thanks for the review. Your suggestion sounds good.
Sorry about the confusion regarding "data".
Have made the changes. Please take a look.

lib/dash/content_protection.js
if (element.schemeUri ===
shaka.dash.ContentProtection.ClearKeySchemeUri_) {
clearKeyInitData =
ContentProtection.getInitDataClearKey_(element, keyIds);
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Should be indented 4, not 2, if I'm not mistaken.

lib/dash/content_protection.js Outdated
}

const Uint8ArrayUtils = shaka.util.Uint8ArrayUtils;
const [first] = keyIds;
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It seems like you should probably use all the key IDs in constructing the PSSH, instead of just the first one.

avelad
avelad reviewed Apr 13, 2022
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lib/util/pssh.js Outdated
* @return {!Uint8Array}
*/
static createPssh(data, systemId) {
static createPssh(data,
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I think all the parameters should go into one line. There is no need to have two lines.

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Sounds good. Will make the change.
Thought there was a line length limit.

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The line limit is 80 characters. :-)

lib/util/pssh.js Outdated
@@ -124,7 +144,6 @@ shaka.util.Pssh = class {
return psshBox;
}


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Is it necessary?

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added the line.

@sr1990 sr1990 requested a review from joeyparrish April 13, 2022 06:31
joeyparrish
joeyparrish approved these changes Apr 13, 2022
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Looks good. Thanks!

@joeyparrish joeyparrish changed the title feat(dash): [ClearKey] Construct pssh box based on ContentProtection … feat(dash): Construct ClearKey PSSH based on MPD ContentProtection Apr 13, 2022
@joeyparrish joeyparrish merged commit b83b412 into shaka-project:main Apr 13, 2022
@github-actions github-actions bot mentioned this pull request Apr 13, 2022
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@avelad avelad added this to the v4.0 milestone May 4, 2022
@github-actions github-actions bot added the status: archived Archived and locked; will not be updated label Jul 25, 2023
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@sr1990 @joeyparrish @avelad