[FFmpeg-devel] [PATCH] lavd/v4l2: do not fail when VIDIOC_ENUMSTD returns ENODATA

Andre Wolokita andre.wolokita at analog.com
Mon Aug 18 04:18:35 CEST 2014

As of September 14 2012, v4l_enumstd() will return ENODATA
when a device's std field is set to 0. That is, the device
does not have a standard format. In order to properly
handle this case, v4l2_set_parameters should catch the
ENODATA code and break instead of failing.

Below is the v4l2-core commit describing this change.

 >>commit a5338190efc7cfa8c99a6856342a77d21c9a05cf
 >>Author: Hans Verkuil <hans.verkuil at cisco.com>
 >>Date:   Fri Sep 14 06:45:43 2012 -0300
 >>    [media] v4l2-core: tvnorms may be 0 for a given input, handle 
that case
 >>    Currently the core code looks at tvnorms to see whether ENUMSTD
 >>    or G_PARM should be enabled. This is not a good check for drivers
 >>    that support the STD API on one input and the DV Timings API on 
 >>    In that case tvnorms may be 0.
 >>    Instead check whether s_std is present (for ENUMSTD) or whether 
g_std or
 >>    current_norm is present for g_parm.
 >>    Also, in the enumstd core function return ENODATA if tvnorms is 0,
 >>    because in that case the current input does not support the STD API
 >>    and ENUMSTD should return ENODATA for that.
 >>    Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
 >>    Reviewed-by: Sakari Ailus <sakari.ailus at iki.fi>
 >>    Signed-off-by: Mauro Carvalho Chehab <mchehab at redhat.com>

Signed-off-by: Andre Wolokita <andre.wolokita at analog.com
  libavdevice/v4l2.c |    2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavdevice/v4l2.c b/libavdevice/v4l2.c
index 64df0c7..fc87d6c 100644
--- a/libavdevice/v4l2.c
+++ b/libavdevice/v4l2.c
@@ -688,7 +688,7 @@ static int v4l2_set_parameters(AVFormatContext *s1)
              standard.index = i;
              if (v4l2_ioctl(s->fd, VIDIOC_ENUMSTD, &standard) < 0) {
                  ret = AVERROR(errno);
-                if (ret == AVERROR(EINVAL)) {
+                if (ret == AVERROR(EINVAL) || ret == AVERROR(ENODATA) {
                      tpf = &streamparm.parm.capture.timeperframe;

More information about the ffmpeg-devel mailing list