[MPlayer-users] Bug in V4L support. Failing VIDIOC_G_STD crashes Mplayer

Jouni.Lohikoski@iki.fi jlohikos at cc.hut.fi
Wed Jun 8 17:36:34 CEST 2005

Pwc webcam driver's V4L2 part does not support ioctl VIDIO_G_STD
It cannot support it, because it doesn't support any of the video
standards available in the table
< http://v4l2spec.bytesex.org/spec/vidioc-enumstd.html#V4L2-STANDARD >

It could return V4L2_STD_UNKNOWN though. But now the ioctl returns just
EINVAL, and that makes Mplayer crash with SIGSEGV.

$ mplayer -tv driver=v4l2:device=/dev/video1:fps=15:width=640:height=480
tv://> MPlayer 1.0pre7-3.4.3 (C) 2000-2005 MPlayer Team

open("/dev/video1", O_RDWR|O_LARGEFILE) = 3
ioctl(3, VIDIOC_QUERYCAP or VT_OPENQRY, 0x86232a4) = 0
ioctl(3, VIDIOC_G_FMT or VT_SENDSIG, 0x8623358) = 0
ioctl(3, VIDIOC_G_STD, 0xbfffdff8)      = -1 EINVAL (Invalid argument)
write(2, "v4l2: ioctl get standard failed:"..., 50v4l2: ioctl get standard failed: Invalid argument
) = 50
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++

MPlayer should have bugzilla.mplayerhq.hu, so bugs would have a ticket
number and would have some sense in fixing the bugs. Currently MPlayer 
crashes too often that I bet many, like me, do not even report them 
anymore or try to debug them.

// jouni

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