1765187 - Video with mismatched matrix coefficients and color primaries will ignore color primaries

Status: RESOLVED FIXED

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

Description

[Brad Werth [:bradwerth]]

What Firefox code refers to as a video's colorspace is derived from the video's matrix coefficients, during the demuxing step of the video pipeline. Later in the video pipeline, Firefox decoders set color primaries and transfer functions based on the colorspace. This works as long as the matrix coefficients match the color primaries.

Instead, Firefox decoders could independently track color primaries and set the corresponding flags when using an OS-defined display compositor.

Comment 1

[Brad Werth [:bradwerth]]

Attachment: BT709_matrix_BT2020_primaries.webm

Output from MediaInfo:

Format                                   : WebM
Format version                           : Version 2
File size                                : 22.8 MiB
Duration                                 : 8 s 341 ms
Overall bit rate                         : 22.9 Mb/s
Writing application                      : Lavf59.16.100
Writing library                          : Lavf59.16.100

Video
ID                                       : 1
Format                                   : VP9
HDR format                               : SMPTE ST 2086, HDR10 compatible
Codec ID                                 : V_VP9
Duration                                 : 8 s 341 ms
Bit rate                                 : 22.0 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Bits/(Pixel*Frame)                       : 0.111
Stream size                              : 21.9 MiB (96%)
Language                                 : English
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.709
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0050 cd/m2, max: 1000 cd/m2

Comment 3

[Brad Werth [:bradwerth]]

Attachment: Bug 1765187 Part 1: Track color primaries independently from coefficients.

Comment 4

[Brad Werth [:bradwerth]]

Attachment: Bug 1765187 Part 2: Make macOS video decoder recognize and use color primaries.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1b7467ce135d
Part 1: Track color primaries independently from coefficients. r=media-playback-reviewers,jgilbert,alwu
https://hg.mozilla.org/integration/autoland/rev/449e728b3f9c
Part 2: Make macOS video decoder recognize and use color primaries. r=media-playback-reviewers,jgilbert,alwu

Comment 6

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/1b7467ce135d
https://hg.mozilla.org/mozilla-central/rev/449e728b3f9c