Bug 226776 – Colorimetry-related warnings with H264 encoded with iOS Safari

• Status: NEW
• Component: WebRTC

[Nazar Mokrynskyi]

When encoding H264 on iOS, its contents doesn't seem to contain colorimetry information when decoded by GStreamer, resulting in following warnings:
> 2:59:30.649107764     1 0x7f0298049400 WARN              video-info video-info.c:204:validate_colorimetry: Need to specify a color matrix when using YUV format (I420)
> 2:59:30.649125302     1 0x7f0298049400 WARN              video-info video-info.c:520:gst_video_info_from_caps: invalid colorimetry, using default

Those warnings are not present when VP8 is used, not present with desktop Safari and H264 (which makes me think it is related to hardware-accelerated encoder) and not present with Firefox/Chromium.

Those are annoying warnings and would be nice to fix in iOS version of Safari.

[youenn fablet]

Thanks Nazar, can you detail whether this is with high profile or baseline?
Can you detail the impact of the issue?

[Nazar Mokrynskyi]

This is baseline. The impact is primarily A HUGE amount of warnings in logs, visually there doesn't seem to be anything bad, I guess GStreamer's default works fine there.

[youenn fablet]

It would help to understand what the spec says here.
That will tell us whether encoder should be fixed, or decoder, or application using decoder output.

[Nazar Mokrynskyi]

Decoding is done by libav integration in GStreamer, so application using it doesn't do anything special.
And since it works fine with every other browser I tried so far except mobile Safari, I believe it is mobile Safari that needs to be tweaked here. But I'm not an expert in the field to suggest something more specific.

[Radar WebKit Bug Importer]

<rdar://problem/79357214>