Bug 236673 - multimedia/gstreamer1-plugins-good 1.14.4: problem with v4l2src
Summary: multimedia/gstreamer1-plugins-good 1.14.4: problem with v4l2src
Status: Closed FIXED
Alias: None
Product: Ports & Packages
Classification: Unclassified
Component: Individual Port(s) (show other bugs)
Version: Latest
Hardware: Any Any
: --- Affects Only Me
Assignee: Christoph Moench-Tegeder
Depends on:
Reported: 2019-03-20 20:03 UTC by Per Gunnarsson
Modified: 2020-05-06 13:57 UTC (History)
3 users (show)

See Also:

catch EINVAL errno when probing DMA capabilities (453 bytes, text/plain)
2020-04-06 19:37 UTC, Christoph Moench-Tegeder
no flags Details

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Description Per Gunnarsson 2019-03-20 20:03:08 UTC
I tried a gst-launch-1.0 which used to work, and which works if I use ximagesrc instead of v4l2src. I got the error message below.

ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Failed to allocate required memory.
Additional debug info:
gstv4l2src.c(658): gst_v4l2src_decide_allocation (): /GstPipeline:pipeline0/GstV4l2Src:v4l2src0:
Buffer pool activation failed

I had problems with cheese too which mentioned v4l2src. The wencam works fine with obs-studio
Comment 1 JavaShin 2019-07-18 01:26:37 UTC
Im having the same problem on 13-current with cheese the webcam works on firefox but not on cheese 

libGL: pci id for fd 16: 8086:0416, driver i965
libGL: OpenDriver: trying /usr/local/lib/dri/i965_dri.so
libGL: Using DRI3 for screen 0

(cheese:58465): Gtk-WARNING **: 21:25:41.380: Theme parsing error: cheese.css:7:35: The style property GtkScrollbar:min-slider-length is deprecated and shouldn't be used anymore. It will be removed in a future version

(cheese:58465): cheese-WARNING **: 21:25:42.168: Failed to allocate required memory.: gstv4l2src.c(658): gst_v4l2src_decide_allocation (): /GstCameraBin:camerabin/GstWrapperCameraBinSrc:camera_source/GstBin:bin35/GstV4l2Src:v4l2src1:
Buffer pool activation failed
Comment 2 Christoph Moench-Tegeder freebsd_committer 2020-04-06 19:37:08 UTC
Created attachment 213136 [details]
catch EINVAL errno when probing DMA capabilities

to be dropped into multimedia/gstreamer1-plugins-good/files/ (bump PORTREVISION on multimedia/gstreamer1-plugins-v4l2).

poking at an old-ish Logitech C270 cam, I noticed the same problem ("Buffer pool activation failed" and camera not working in gstreamer-based applications).
Working backwards through gstreamer and cuse) it became obvious that gstreamer probes the DMA capabilities of the device using ioctls, expecting ENOTTY (as it is customary when the request is not applicable to the object in question) in case DMA capabilities are not available. Unfortunately, FreeBSD's cuse returns EINVAL for this ioctl.

As it's easier to fix the port than to fix the kernel: Here's the workaround, catching both ENOTTY and EINVAL on the DMA probing. With that, my camery works with gstreamer.
Comment 3 Christoph Moench-Tegeder freebsd_committer 2020-04-06 19:39:32 UTC
hselasky: as the author of cuse, can you give some input on the ioctls here?
Comment 4 commit-hook freebsd_committer 2020-05-06 13:53:54 UTC
A commit references this bug:

Author: cmt
Date: Wed May  6 13:53:34 UTC 2020
New revision: 534176
URL: https://svnweb.freebsd.org/changeset/ports/534176

  gstreamer1-plugins-v4l2: fix for (some) webcams

  The gstreamer v4l2 plugin probes the DMA capabilities of the webcam
  device via ioctl VIDIOC_EXPBUF, expecting ENOTTY in case that's not
  implemented (and will act accordingly). On our cuse, we get EINVAL
  for that case (which, from my reading of ioctl(2) woulndn't be correct
  here), which gstreamer neither expects nor handles and thus cannot
  use this device as a video source. As we cannot fix the kernel on short
  notice (cuse is part of the base system), the workaround is to handle
  EINVAL like ENOTTY in this specific place. (Tested with an old
  Logitech camera).

  PR:		236673
  Approved by:	maintainer-timeout (multimedia)

Comment 5 Christoph Moench-Tegeder freebsd_committer 2020-05-06 13:57:43 UTC
committed as ports r534176