Hi,
On 06/29/2011 02:01 PM, Mauro Carvalho Chehab wrote:
Em 29-06-2011 08:01, Hans de Goede escreveu:
Hi,
On 06/28/2011 07:32 PM, Mauro Carvalho Chehab wrote:
This is an automatic generated email to let you know that the following patch were queued at the
http://git.linuxtv.org/xawtv3.git tree:
Subject: xawtv: reenable its usage with webcam's
Author: Mauro Carvalho Chehab<mchehab@xxxxxxxxxx>
Date: Tue Jun 28 14:22:55 2011 -0300
git changeset c28978f3693bc0f40607d0b3e589774b9452608d was requiring that
tuner would be available, in order to allow it to run. Relax the restriction,
in order to allow using xawtv to test webcams, restoring the previous
behavior.
Signed-off-by: Mauro Carvalho Chehab<mchehab@xxxxxxxxxx>
libng/grab-ng.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
---
http://git.linuxtv.org/xawtv3.git?a=commitdiff;h=2238f79d9fb2801a3acd114242b437686fa2f0c8
diff --git a/libng/grab-ng.c b/libng/grab-ng.c
index f5203cc..94f31e8 100644
--- a/libng/grab-ng.c
+++ b/libng/grab-ng.c
@@ -563,9 +563,9 @@ static void *ng_vid_open_auto(struct ng_vid_driver *drv, char *devpath)
continue;
}
- /* Check caps return this device if it can capture and has a tuner */
+ /* Check caps return this device if it can capture */
caps = drv->capabilities(handle);
- if ((caps& CAN_CAPTURE)&& (caps& CAN_TUNE))
+ if (caps& CAN_CAPTURE)
break;
drv->close(handle);
Hmm, this changes the behavior from what I intended, the idea was to select the
first *tv-card*, without checking for a tuner, there is little value in the auto
device feature. Granted it will still skip v4l2 output only devices but those are
very rare.
Your patch broke support for vivi and for video grabber devices. Those devices don't
have a tuner.
I did no such thing as "break support". The new xawtv will still work fine with
them with an explicit "-c /dev/video#" argument.
Note that only the xawtv binary is using a device value of "auto" by default,
the webcam tool still defaults to /dev/video0
It is not "by default", as there's was way to override the CAN_TUNE check logic.
calling xawtv without my changes with vivi or a webcam would simply return as if
there's no supported V4L device.
One can override the CAN_TUNE logic quite simply, revert your patch and do:
xawtv -c /dev/video#
On a device without a tuner, and it will work fine, if you don't specify the
device and don't have a device with a tuner you will get the following error:
vid-open: could not find a suitable videodev
Which sounds like a sane error for a tv viewing app when it cannot find
a tv-card. Granted, maybe the error should be changed to:
vid-open: could not find a suitable tv-card
To make things even more clear.
This is only the default behavior, and in *no way* have I *broken* use
with a webcam, simply doing:
xawtv -c /dev/video#
Will work fine with any device which worked before as can been clearly
seen from the new code:
+#ifdef __linux__
+ if (!strcmp(*device, "auto")) {
+ char devpath[PATH_MAX];
+ *handle = ng_vid_open_auto(drv, devpath);
+ if (*handle == NULL) {
+ fprintf(stderr, "vid-open: could not find a suitable videodev\n");
+ return NULL;
+ }
+ *device = strdup(devpath);
+ } else
+#endif
+ {
+ if (ng_debug)
+ fprintf(stderr,"vid-open: trying: %s... \n", drv->name);
+ if (!(*handle = (drv->open)(*device))) {
+ fprintf(stderr,"vid-open: failed: %s\n", drv->name);
+ return NULL;
+ }
+ if (ng_debug)
+ fprintf(stderr,"vid-open: ok: %s\n", drv->name);
}
Specify anything other then auto and the code you've changed simply does
not get called.
Given that xawtv is specifically meant for tv-cards (unlike the webcam tool)
failing if it cannot find a tv-card and no device is explicitly specified seems
reasonable.
Well, xawtv ever worked also with webcams, and with the libv4l, it is now
working even better. I don't see any reason why removing such support for it.
Again I did not remove support for that, you should have studied my patch /
the problem a bit better before making such claims.
Btw, with the changes I've made, the TV-specific controls are now removed if
the device is a grabber or a webcam.
Nice!
There's currently just one detail to be
fixed: the window title will be changed to "???" on those devices. This is an
old bug, as changing from Television to S-Video or Composite, on a device that
has both tuner and grabber capabilities, it will still keep the channel name
there. It probably makes sense to print there the input name instead, if the
input is not Television.
Agreed.
Alternatively we could make the desired caps a param too ng_vid_open_auto
and first try with (CAN_CAPTURE | CAN_TUNE) and then retry with only
CAN_CAPTURE.
A logic like that would be better, although, IMO, we should print a message
saying that we're not using video0. Also, if we're willing to do such logic,
it makes sense to implement the auto mode also for "scantv".
Why should we print a message that we're not using video0? In the modern
dynamic device discovery world, the # in /dev/video# is as good as meaningless.
The above patch definitely is not what I had in mind. My system has a
bt878 tv card, and a varying number of webcams connected, thus constantly
changing the /dev/video# for the tv-card. The intent of my "auto" device
patches was to make xawtv automatically pick the tvcard.
Well, a varying device for /dev/video is something that we need to fix at udev.
There are some ways to create persistent rules for that.
In a matter of fact, IMO, we should change the V4L2 device nodes reported via
udev, to be more intuitive, e. g. instead of creating /dev/video for everything,
create /dev/webcam? /dev/grabber? /dev/analog_tv? device nodes, while creating
a symlink to /dev/video, in order to not break existing applications that have
it hardcoded.
That sounds like a good idea, but first needs to be written and then make its
way into distributions, I wanted something which would improve the user experience
right now, rather then in 2 years.
I intented to mail you about my get_media_devices fixes as well as my
auto device patches, and suggest that we do a new release soon.
Yes, I think we should make a release for it soon. There are enough features
added on xawtv that justifies doing a new release.
Agreed,
Regards,
Hans
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