2056029 - Buffers with padding (stride bigger than width*bpp) are not supported (breaking negotiation with libcamera in some cases)

Status: ASSIGNED

(Core :: WebRTC, task)

Description

[Robert Mader [:rmader]]

From https://gitlab.freedesktop.org/pipewire/pipewire/-/work_items/5285: sometimes buffer allocations fail if the buffer stride chosen by the PW camera plugin - notably libcamera when using the softISP with GPU backend - includes padding. Camera backends sometimes require padding, so this is hard to fix on the PW/libcamera side - let's just add support padded buffers. We can do so by either doing a copy - line-by-line - or using some existing utilities for that.

Edit: the relevant code is around here: https://searchfox.org/firefox-main/rev/7f94689f2c228a96f6c271e30880e72778b7ab15/third_party/libwebrtc/modules/video_capture/linux/video_capture_pipewire.cc#355-383

Comment 1

[Robert Mader [:rmader]]

Attachment: WIP: Bug 2056029 - Implement stride handling for libwebrtc video capture

A very simple ad-hoc implementation for now.

Comment 2

[Robert Mader [:rmader]]

See https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/105605 for an experimental build for postmarketOS.

Comment 3

[Robert Mader [:rmader]]

The latest push seems to work pretty well - but requires a change to libyuv, on top of libwebrtc. Upstreaming will thus take some effort.

Comment 4

[Robert Mader [:rmader]]

Opened https://issues.chromium.org/issues/538875176 / https://chromium-review.googlesource.com/c/libyuv/libyuv/+/8146821 /