Re: nasty bug at qv4l2

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Em 24-12-2010 16:54, Hans Verkuil escreveu:
> On Friday, December 24, 2010 15:41:10 Hans de Goede wrote:
>> Hi,
>>
>> On 12/24/2010 03:20 PM, Hans Verkuil wrote:
>>> On Friday, December 24, 2010 15:19:26 Hans de Goede wrote:
>>>> Hi,
>>>>
>>>> On 12/22/2010 12:30 PM, Mauro Carvalho Chehab wrote:
>>>>> Hans V/Hans G,
>>>>>
>>>>> There's a nasty bug at qv4l2 or at libv4l: it is not properly updating
>>>>> all info, if you change the video device. On my tests with uvcvideo (video0)
>>>>> and a gspca camera (pac7302, video1), it was showing the supported formats
>>>>> for the uvcvideo camera when I changed from video0 to video1.
>>>>>
>>>>> The net result is that the image were handled with the wrong decoder
>>>>> (instead of using fourcc V4L2_PIX_FMT_PJPG, it were using BGR3), producing
>>>>> a wrong decoding.
>>>>>
>>>>> Could you please take a look on it?
>>>>
>>>> I'm pretty sure this is not a libv4l issue (other apps which allows witching
>>>> the source work fine), but rather a qv4l2 problem, esp. as it uses libv4lconvert
>>>> directly rather then going through libv4l (iirc).
>>>
>>> And I'm pretty sure it isn't a qv4l2 issue :-)
>>>
>>> For the record: qv4l2 can open a device node either in 'raw' mode bypassing libv4l
>>> and using v4lconvert to convert unsupported pixformats, or in 'wrapped' mode where
>>> libv4l is used for all device node accesses.
>>>
>>
>> Interesting, how does it switch between the modes?
> 
> In the File menu there is an entry "Open device" (uses libv4l) and "Open raw device"
> (opens the device node directly).
> 
> Depending on how the device is opened, all calls to the device node either go through
> libv4l or are direct system calls.
> 
>> Mauro were you using wrapped mode
>> or raw mode when you saw this ?
> 
> The button on the toolbar will always use libv4l. But if you add the device node on
> the command line (e.g. qv4l2 /dev/video0), then it will open the device node in raw
> mode. That's rather inconsistent and it should also use libv4l. I've just fixed
> this: 'qv4l2 /dev/video0' will now also use libv4l. If you want to test a device node
> bypassing libv4l, then you have to open the device node using "Open raw device" in
> the File menu.

Maybe you may add a "--raw" parameter for the command line call.
> 
> I wonder if Mauro got confused by the different behavior as well.

I think I used the libv4l way. I'll re-try on both modes. This way, we'll know for sure if
the issue is at libv4l or not.

Cheers,
Mauro