2008-08-04 11:17:18

by Mario 'BitKoenig' Holbe

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Subject: bttv: video grabbing via v4l1 does not work since 2.6.25

Hello,

with 2.6.25 bttv video grabbing via vlc stopped working.
vlc is stable version 0.8.6.h which uses v4l(1) interface only.
Up to 2.6.24 everything was working well.
I suspect the reason to be somewhere in the v4l1->v4l2 conversion done
in 2.6.25:

commit 402aa76aa5e57801b4db5ccf8c7beea9f580bb1b
Author: Douglas Schilling Landgraf <[email protected]>
V4L/DVB (6911): Converted bttv to use video_ioctl2

commit e84619b17440ccca4e4db7583d126c4189b987e5
Author: Nickolay V. Shmyrev <[email protected]>
V4L/DVB (6410): Partial conversion from V4L1 to V4L2

Video capturing via xawtv (overlay as well as grabdisplay method) does
still work with 2.6.25/26.

I attached the relevant dmesg snippets from bttv initialization and vlc
debugging output both for 2.6.24 and 2.6.26 as well as v4l1-compat debug
messages for 2.6.26 (there are no v4l1-compat messages for 2.6.24).

It seems like vlc is no longer able to select the I420 chroma. Please
also note the changed vlc device recognition from "1 audios" to
"0 audios" in .26. Audio grabbing did stop working as well.

The card in question is a Hauppauge WinTV PCI FM.
The vlc commandline is:
vlc -vv v4l:///dev/video0:adev=/dev/dsp:audio=0:tuner=0:norm=pal:frequency=182250:size=720x576

If you need more info, please let me know.

Please CC: me in replies, M-F'up2 should be set correctly.


regards
Mario
--
There are two major products that come from Berkeley: LSD and UNIX.
We don't believe this to be a coincidence. -- Jeremy S. Anderson


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2008-10-16 19:31:39

by Mario 'BitKoenig' Holbe

[permalink] [raw]
Subject: Re: bttv: video grabbing via v4l1 does not work since 2.6.25

Hello again,

even though I doubt somebody cares, I tried to collect some more
information in the vague hope to get previously working features back,
maybe in two years or three...

On Mon, Aug 04, 2008 at 01:16:54PM +0200, Mario 'BitKoenig' Holbe wrote:
> with 2.6.25 bttv video grabbing via vlc stopped working.
> vlc is stable version 0.8.6.h which uses v4l(1) interface only.
> Up to 2.6.24 everything was working well.

With the release of vlc 0.9 I can confirm that grabbing over V4L2 works,
V4L, of course, is still broken.

> Please also note the changed vlc device recognition from "1 audios" to
> "0 audios" in .26.

The reason for this is probably that the volume control disappeared
(which was there and working in .24, of course). mute, balance, bass and
trebble controls are still there and working in .26 and to some extent
the driver seems to have some knowledge about a "volume" as well, as
v4l2-dbg --log-status shows. And some applications are somehow able to
set it to 0 from time to time - re-adjusting it is quite hard without
the volume control mentioned above.


Mario
--
Doing it right is no excuse for not meeting the schedule.
-- Plant Manager, Delphi Corporation


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