1776361 - Issue with DASH Media Encryption for video streams with multiple sub-samples.

Status: UNCONFIRMED

(Core :: Audio/Video: Playback, defect, P3)

Description

[Adarsha Manjunatha]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.0.0 Safari/537.36

Steps to reproduce:

Encrypted DASH video segments according to the ISO specifications and tried the playback on DASH js player on Firefox browser.

Player used for testing: DASH js player (https://reference.dashif.org/dash.js/nightly/samples/dash-if-reference-player/index.html)

Browser's user agent string: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:101.0) Gecko/20100101 Firefox/101.0

Firefox version: 101.0.1 (64-bit)

Actual results:

Playback of DASH Media Encrypted stream on DASH js player has distortions when video samples contain more than one sub-sample.

Video playback works fine without distortions when each sample has only one sub-sample. Example 'senc' box:
<SampleEncryptionBox Size="400" Type="senc" Specification="cenc" Container="trak traf" sampleCount="48">
<FullBoxInfo Version="0" Flags="0x2"/>
<SampleEncryptionEntry sampleNumber="1" IV_size="0" SubsampleCount="1">
<SubSampleEncryptionEntry NumClearBytes="768" NumEncryptedBytes="1371"/>
</SampleEncryptionEntry>
<SampleEncryptionEntry sampleNumber="2" IV_size="0" SubsampleCount="1">
<SubSampleEncryptionEntry NumClearBytes="10" NumEncryptedBytes="108"/>
</SampleEncryptionEntry>
...

When each sample contains multiple sub-samples, playback has distortions. Example 'senc' box:
<SampleEncryptionBox Size="1576" Type="senc" Specification="cenc" Container="trak traf" sampleCount="60">
<FullBoxInfo Version="0" Flags="0x2"/>
<SampleEncryptionEntry sampleNumber="1" IV_size="0" SubsampleCount="4">
<SubSampleEncryptionEntry NumClearBytes="48" NumEncryptedBytes="43572"/>
<SubSampleEncryptionEntry NumClearBytes="13" NumEncryptedBytes="44958"/>
<SubSampleEncryptionEntry NumClearBytes="13" NumEncryptedBytes="39499"/>
<SubSampleEncryptionEntry NumClearBytes="13" NumEncryptedBytes="37690"/>
</SampleEncryptionEntry>
<SampleEncryptionEntry sampleNumber="2" IV_size="0" SubsampleCount="4">
<SubSampleEncryptionEntry NumClearBytes="32" NumEncryptedBytes="3469"/>
<SubSampleEncryptionEntry NumClearBytes="12" NumEncryptedBytes="2760"/>
<SubSampleEncryptionEntry NumClearBytes="12" NumEncryptedBytes="3787"/>
<SubSampleEncryptionEntry NumClearBytes="13" NumEncryptedBytes="4037"/>
</SampleEncryptionEntry>
...

Please note that there were no error messages seen on the console.

Expected results:

Playback should be seamless without any distortions.

Please note that this issue is NOT observed on Chrome. Same encrypted video stream plays seamlessly on the chrome browser.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:jimm, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 2

[az [:az]]

Thanks for the report!

To help diagnose, can you please capture a profile using the Firefox Profiler with the media preset? Please also copy and paste the results of your about:support page.

I was unable to repro, though I might be missing a setting on my side. Would it be possible to click the "Copy Settings URL" button on the DASH js page and share the results? :alwu, would you have any insights here?

Comment 3

[Alastor Wu [:alwu]]

Unfortunately I am not familiar with the encrypted content. It would be great if you could help us capture debug log by using MOZ_LOG=MediaFormatReader:5,MediaDecoder:5,EME:5. Thank you.

Comment 4

[secretchin27]

Attachment: debug logs.zip - Debug logs

Comment 5

[secretchin27]

(In reply to Alastor Wu [:alwu] from comment #3)

Unfortunately I am not familiar with the encrypted content. It would be great if you could help us capture debug log by using MOZ_LOG=MediaFormatReader:5,MediaDecoder:5,EME:5. Thank you.

I have attached the debug logs. Please take a look.