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Webcam resolution in VLC (and elsewhere)

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  Webcam resolution in VLC (and elsewhere) Celejar <celejar@gmail.com> - 2020-12-30 16:40 +0100
    Re: Webcam resolution in VLC (and elsewhere) didier gaumet <didier.gaumet@gmail.com> - 2020-12-30 20:20 +0100
      Re: Webcam resolution in VLC (and elsewhere) Celejar <celejar@gmail.com> - 2020-12-31 17:00 +0100
        Re: Webcam resolution in VLC (and elsewhere) Michael Stone <mstone@debian.org> - 2020-12-31 17:20 +0100
          Re: Webcam resolution in VLC (and elsewhere) Celejar <celejar@gmail.com> - 2021-01-01 16:00 +0100
            Re: Webcam resolution in VLC (and elsewhere) Michael Stone <mstone@debian.org> - 2021-01-01 18:50 +0100
              Re: Webcam resolution in VLC (and elsewhere) Celejar <celejar@gmail.com> - 2021-01-01 22:20 +0100
        Re: Webcam resolution in VLC (and elsewhere) Gene Heskett <gheskett@shentel.net> - 2020-12-31 18:20 +0100
          Re: Webcam resolution in VLC (and elsewhere) Brian <ad44@cityscape.co.uk> - 2021-01-08 21:20 +0100
            Re: Webcam resolution in VLC (and elsewhere) Charles Curley <charlescurley@charlescurley.com> - 2021-01-09 00:50 +0100
              Re: Webcam resolution in VLC (and elsewhere) Brian <ad44@cityscape.co.uk> - 2021-01-09 01:20 +0100
                Re: Webcam resolution in VLC (and elsewhere) Charles Curley <charlescurley@charlescurley.com> - 2021-01-09 02:10 +0100
                Re: Webcam resolution in VLC (and elsewhere) Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-09 07:30 +0100
                  Re: Webcam resolution in VLC (and elsewhere) David <bouncingcats@gmail.com> - 2021-01-09 13:30 +0100
                    Re: Webcam resolution in VLC (and elsewhere) rhkramer@gmail.com - 2021-01-09 15:50 +0100
                  Re: Webcam resolution in VLC (and elsewhere) Brian <ad44@cityscape.co.uk> - 2021-01-09 21:30 +0100
    Re: Webcam resolution in VLC (and elsewhere) didier gaumet <didier.gaumet@gmail.com> - 2020-12-30 20:30 +0100
      Re: Webcam resolution in VLC (and elsewhere) Celejar <celejar@gmail.com> - 2020-12-31 17:00 +0100
    Re: Webcam resolution in VLC (and elsewhere) Eugen Dedu <eugen.dedu@univ-fcomte.fr> - 2020-12-31 22:10 +0100
      Re: Webcam resolution in VLC (and elsewhere) Celejar <celejar@gmail.com> - 2021-01-01 15:50 +0100

#230129 — Webcam resolution in VLC (and elsewhere)

Hi,

I'm puzzled by VLC's handling of my webcam. When I open it using
default settings, either via the GUI or CLI ('vlc v4l2://'), it opens
(according to 'Tools / Media Information / Codec') in 848x480. The
camera supports HD, however, and I can get that by 'vlc
v4l2://:width=1280:height=720' (or by making up random higher numbers
for width and height).

1) Why does VLC default to the lower resolution? Incidentally, I see
that Cheese also opens the camera by default at a lower resolution -
but a different one: 960x540. Why? Is this to save space when recording?

2) VLC's GUI doesn't seem to offer any way to set the resolution.
I see all kind of references on the internet to knobs to turn to set
resolution, but none of them seem available in my VLC when using a v4l2
camera. Why?

VLC's documentation is often terrible, and in this case, it says:

"For Video4Linux devices, you can set the name of the video and audio
devices using the "Video device name" and "Audio device name" text
inputs. The "Advanced options..." button allows you to select some
further settings useful in some rare cases, such as the chroma of the
input (the way colors are encoded) and the size of the input buffer."

https://wiki.videolan.org/Documentation:Open_Media/#Play_from_an_acquisition_card

So does this mean what I think it means? The standard settings don't
have a resolution knob, and neither do the advanced ones (which should
only be necessary "in some rare cases" anyway)?

Here's VLC's v4l2 module's (CLI) documentation:

https://wiki.videolan.org/Documentation:Modules/v4l2/

So there's no way to just tell VLC to use the highest resolution, and
the user has to somehow figure out that he has to first discover the
offered resolutions via something like lsusb or Cheese [0], and then enter
them manually via the 'width' and 'height' parameters?!

Who designed this thing's UIs? At least Cheese offers a relatively
straightforward way of setting the resolution.

[0] https://askubuntu.com/questions/214977/how-can-i-find-out-the-supported-webcam-resolutions

Celejar

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#230137

Le mercredi 30 décembre 2020 à 16:40:06 UTC+1, Celejar a écrit :
[...]
> 1) Why does VLC default to the lower resolution? Incidentally, I see 
> that Cheese also opens the camera by default at a lower resolution - 
> but a different one: 960x540. Why? Is this to save space when recording? 

I don't know: one possibility is that either Linux or VLC/Cheese incorrectly detects the webcam resolution? Another possibility could be a marketing trick: an higher resolution is claimed through interpolation  while actual optical resolution is lower.

> 2) VLC's GUI doesn't seem to offer any way to set the resolution. 
> I see all kind of references on the internet to knobs to turn to set 
> resolution, but none of them seem available in my VLC when using a v4l2 
> camera. Why? 

I use VLC from Buster. the following is the rough english translation of my VLC that is in french.

- To set up the resolution of the webcam for a session and begin the session:  Media>Open a capture device, then set up the capture mode to video camera, click on advanced options button and fill the width and height fields.
- To set up the default resolution of the webcam: Tools>Preferences, then click on display parameters: all, then input/codecs>access modules>v4l, fill the width and height fields

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#230168

On Wed, 30 Dec 2020 10:53:37 -0800 (PST)
didier gaumet <didier.gaumet@gmail.com> wrote:

> Le mercredi 30 décembre 2020 à 16:40:06 UTC+1, Celejar a écrit :
> [...]
> > 1) Why does VLC default to the lower resolution? Incidentally, I see 
> > that Cheese also opens the camera by default at a lower resolution - 
> > but a different one: 960x540. Why? Is this to save space when recording? 
> 
> I don't know: one possibility is that either Linux or VLC/Cheese
> incorrectly detects the webcam resolution? Another possibility could be

The manufacturer claims that it's 720p HD:

https://www.lenovo.com/us/en/laptops/thinkpad/w-series/w550s/

> a marketing trick: an higher resolution is claimed through
> interpolation  while actual optical resolution is lower.

I don't know how to evaluate this. But still, if the camera is
reporting 720p, shouldn't the applications default to that? Do they
somehow figure out that the 720p mode is cheating and therefore ignore
it by default?

> > 2) VLC's GUI doesn't seem to offer any way to set the resolution. 
> > I see all kind of references on the internet to knobs to turn to set 
> > resolution, but none of them seem available in my VLC when using a v4l2 
> > camera. Why? 
> 
> I use VLC from Buster. the following is the rough english translation of my VLC that is in french.
> 
> - To set up the resolution of the webcam for a session and begin the session:  Media>Open a capture device, then set up the capture mode to video camera, click on advanced options button and fill the width and height fields.
> - To set up the default resolution of the webcam: Tools>Preferences, then click on display parameters: all, then input/codecs>access modules>v4l, fill the width and height fields

You're right, I was mistaken. The Advanced option do contain height and
width fields (parelleling the height and width CLI parameters I
mentioned).

But I still think it's ridiculous that a) VLC doesn't provide a list of
supported resolutions to choose from, instead making the user figure
these out using other tools, and then enter the values manually and b)
hides these fields under the Advanced options, which, as I noted, the
documentation describes as "useful in some rare cases"

Celejar

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#230169

On Thu, Dec 31, 2020 at 10:59:36AM -0500, Celejar wrote:
>I don't know how to evaluate this. But still, if the camera is
>reporting 720p, shouldn't the applications default to that?

The optical quality on most small web cams is so bad that increasing the 
resolution just means significantly more bandwidth is used to produce a 
picture that's visually indistinguishable from the lower resolution 
version. Most video chat applications will downsample a high res image 
anyway, so generating a high res stream is just making more work. There 
are cameras and applications where the increased resolution matter, but 
they're the exception IME.

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#230193

On Thu, 31 Dec 2020 11:13:54 -0500
Michael Stone <mstone@debian.org> wrote:

> On Thu, Dec 31, 2020 at 10:59:36AM -0500, Celejar wrote:
> >I don't know how to evaluate this. But still, if the camera is
> >reporting 720p, shouldn't the applications default to that?
> 
> The optical quality on most small web cams is so bad that increasing the 
> resolution just means significantly more bandwidth is used to produce a 
> picture that's visually indistinguishable from the lower resolution 
> version. Most video chat applications will downsample a high res image 
> anyway, so generating a high res stream is just making more work. There 
> are cameras and applications where the increased resolution matter, but 
> they're the exception IME.

Very interesting, thanks. Zoom does offer standard HD and even FHD in
some cases:

https://support.zoom.us/hc/en-us/articles/115002595343-Video-enhancements#h_01EEEKVD06W1QDZ5GXCS2B9KYN
https://support.zoom.us/hc/en-us/articles/207347086-Group-HD

Celejar

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#230201

On Fri, Jan 01, 2021 at 09:50:00AM -0500, Celejar wrote:
>On Thu, 31 Dec 2020 11:13:54 -0500
>Michael Stone <mstone@debian.org> wrote:
>
>> On Thu, Dec 31, 2020 at 10:59:36AM -0500, Celejar wrote:
>> >I don't know how to evaluate this. But still, if the camera is
>> >reporting 720p, shouldn't the applications default to that?
>>
>> The optical quality on most small web cams is so bad that increasing the
>> resolution just means significantly more bandwidth is used to produce a
>> picture that's visually indistinguishable from the lower resolution
>> version. Most video chat applications will downsample a high res image
>> anyway, so generating a high res stream is just making more work. There
>> are cameras and applications where the increased resolution matter, but
>> they're the exception IME.
>
>Very interesting, thanks. Zoom does offer standard HD and even FHD in
>some cases:

"Note: Due to recent events with COVID-19, meetings in 720p-quality 
video are only available to Pro account users or higher, and only for 
meetings with a maximum of 2 participants; 1080p quality is for 
special-use cases currently."

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#230209

On Fri, 1 Jan 2021 12:41:38 -0500
Michael Stone <mstone@debian.org> wrote:

> On Fri, Jan 01, 2021 at 09:50:00AM -0500, Celejar wrote:
> >On Thu, 31 Dec 2020 11:13:54 -0500
> >Michael Stone <mstone@debian.org> wrote:
> >
> >> On Thu, Dec 31, 2020 at 10:59:36AM -0500, Celejar wrote:
> >> >I don't know how to evaluate this. But still, if the camera is
> >> >reporting 720p, shouldn't the applications default to that?
> >>
> >> The optical quality on most small web cams is so bad that increasing the
> >> resolution just means significantly more bandwidth is used to produce a
> >> picture that's visually indistinguishable from the lower resolution
> >> version. Most video chat applications will downsample a high res image
> >> anyway, so generating a high res stream is just making more work. There
> >> are cameras and applications where the increased resolution matter, but
> >> they're the exception IME.
> >
> >Very interesting, thanks. Zoom does offer standard HD and even FHD in
> >some cases:
> 
> "Note: Due to recent events with COVID-19, meetings in 720p-quality 
> video are only available to Pro account users or higher, and only for 
> meetings with a maximum of 2 participants; 1080p quality is for 
> special-use cases currently."

Yes - that's what it says on the page that I linked to. And I have a
Pro account at work, and I often have extended one-on-one meetings with
a total of exactly two participants ;)

https://support.zoom.us/hc/en-us/articles/115002595343-Video-enhancements#h_01EEEKVD06W1QDZ5GXCS2B9KYN

Celejar

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#230170

On Thursday 31 December 2020 10:59:36 Celejar wrote:

> On Wed, 30 Dec 2020 10:53:37 -0800 (PST)
>
> didier gaumet <didier.gaumet@gmail.com> wrote:
> > Le mercredi 30 décembre 2020 à 16:40:06 UTC+1, Celejar a écrit :
> > [...]
> >
> > > 1) Why does VLC default to the lower resolution? Incidentally, I
> > > see that Cheese also opens the camera by default at a lower
> > > resolution - but a different one: 960x540. Why? Is this to save
> > > space when recording?
> >
> > I don't know: one possibility is that either Linux or VLC/Cheese
> > incorrectly detects the webcam resolution? Another possibility could
> > be
>
> The manufacturer claims that it's 720p HD:
>
> https://www.lenovo.com/us/en/laptops/thinkpad/w-series/w550s/
>
> > a marketing trick: an higher resolution is claimed through
> > interpolation  while actual optical resolution is lower.
>
> I don't know how to evaluate this. But still, if the camera is
> reporting 720p, shouldn't the applications default to that? Do they
> somehow figure out that the 720p mode is cheating and therefore ignore
> it by default?
>
> > > 2) VLC's GUI doesn't seem to offer any way to set the resolution.
> > > I see all kind of references on the internet to knobs to turn to
> > > set resolution, but none of them seem available in my VLC when
> > > using a v4l2 camera. Why?
> >
> > I use VLC from Buster. the following is the rough english
> > translation of my VLC that is in french.
> >
> > - To set up the resolution of the webcam for a session and begin the
> > session:  Media>Open a capture device, then set up the capture mode
> > to video camera, click on advanced options button and fill the width
> > and height fields. - To set up the default resolution of the webcam:
> > Tools>Preferences, then click on display parameters: all, then
> > input/codecs>access modules>v4l, fill the width and height fields
>
> You're right, I was mistaken. The Advanced option do contain height
> and width fields (parelleling the height and width CLI parameters I
> mentioned).
>
> But I still think it's ridiculous that a) VLC doesn't provide a list
> of supported resolutions to choose from, instead making the user
> figure these out using other tools, and then enter the values manually
> and b) hides these fields under the Advanced options, which, as I
> noted, the documentation describes as "useful in some rare cases"
>
> Celejar


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>

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#230451

On Thu 31 Dec 2020 at 12:15:13 -0500, Gene Heskett wrote:

[Snipped Celejar's comments. The only thing added to it is below]

> Cheers, Gene Heskett

> -- 
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."

DT tried the soapbox. It didn't work out.

DT was spurned at the ballot box.

Jury box? The legal system didn't substantiate any of DT's
untrue claims.

DT's supporters resorted to the ammo box with his support.
Only five dead. Is that a good result?

> -Ed Howdershelt (Author)

Someone who believes in radicalising people? We see what that
has led to in other parts of the world.

-- 
Brian.

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#230458

On Fri, 8 Jan 2021 20:10:05 +0000
Brian <ad44@cityscape.co.uk> wrote:

> > -- 
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."  
> 
> DT tried the soapbox. It didn't work out.

...

> > -Ed Howdershelt (Author)  
> 
> Someone who believes in radicalising people? We see what that
> has led to in other parts of the world.

This is inappropriate on this list. Please take it elsewhere. Thank you.

-- 
Does anybody read signatures any more?

https://charlescurley.com
https://charlescurley.com/blog/

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#230460

On Fri 08 Jan 2021 at 16:46:53 -0700, Charles Curley wrote:

> On Fri, 8 Jan 2021 20:10:05 +0000
> Brian <ad44@cityscape.co.uk> wrote:
> 
> > > -- 
> > > "There are four boxes to be used in defense of liberty:
> > >  soap, ballot, jury, and ammo. Please use in that order."  
> > 
> > DT tried the soapbox. It didn't work out.
> 
> ...
> 
> > > -Ed Howdershelt (Author)  
> > 
> > Someone who believes in radicalising people? We see what that
> > has led to in other parts of the world.
> 
> This is inappropriate on this list. Please take it elsewhere. Thank you.

The political statement inciting violence I responded to is also
inappropriate. That is to be tolerated?

-- 
Brian.

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#230461

On Sat, 9 Jan 2021 00:13:06 +0000
Brian <ad44@cityscape.co.uk> wrote:

> > This is inappropriate on this list. Please take it elsewhere. Thank
> > you.  
> 
> The political statement inciting violence I responded to is also
> inappropriate. That is to be tolerated?

Take it elsewhere.

-- 
Does anybody read signatures any more?

https://charlescurley.com
https://charlescurley.com/blog/

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#230465

[Multipart message — attachments visible in raw view] — view raw

On Sb, 09 ian 21, 00:13:06, Brian wrote:
> On Fri 08 Jan 2021 at 16:46:53 -0700, Charles Curley wrote:
> > 
> > This is inappropriate on this list. Please take it elsewhere. Thank you.
> 
> The political statement inciting violence I responded to is also
> inappropriate. That is to be tolerated?

Arguing whether something is inappropriate or not is also inappropriate 
for debian-user, so I will refrain from doing so.

I kindly ask other list subscribers to do the same.

If you think something posted on debian-user is in violation of the 
Debian Code of Conduct please contact the Debian Community Team.

https://www.debian.org/code_of_conduct
https://wiki.debian.org/Teams/Community

Kind regards,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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#230470

On Sat, 9 Jan 2021 at 17:19, Andrei POPESCU <andreimpopescu@gmail.com> wrote:

> If you think something posted on debian-user is in violation of the
> Debian Code of Conduct please contact the Debian Community Team.

I've always found email signatures to be entirely pointless,
except that they help me to identify people to avoid.

Especially on mailing lists where we get to read the
stupid things over and over again.

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#230482

On Saturday, January 09, 2021 07:25:57 AM David wrote:
> Especially on mailing lists where we get to read the
> stupid things over and over again.

+1 (or more)

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#230488

On Sat 09 Jan 2021 at 08:19:36 +0200, Andrei POPESCU wrote:

> On Sb, 09 ian 21, 00:13:06, Brian wrote:
> > On Fri 08 Jan 2021 at 16:46:53 -0700, Charles Curley wrote:
> > > 
> > > This is inappropriate on this list. Please take it elsewhere. Thank you.
> > 
> > The political statement inciting violence I responded to is also
> > inappropriate. That is to be tolerated?
> 
> Arguing whether something is inappropriate or not is also inappropriate 
> for debian-user, so I will refrain from doing so.
> 
> I kindly ask other list subscribers to do the same.
> 
> If you think something posted on debian-user is in violation of the 
> Debian Code of Conduct please contact the Debian Community Team.
> 
> https://www.debian.org/code_of_conduct
> https://wiki.debian.org/Teams/Community

Thanks for this.

The poster may, of course, reconsider the wisdom of advocating the
assault on a democratcally elected government by violent means and
decide to remove his support of the statement from his posts. We can
rely on good sense instead of arm twisting? 

I am havng trouble working out which heading of the Code of Conduct
applied to the post I commented on.

-- 
Brian.

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#230140

Le mercredi 30 décembre 2020 à 16:40:06 UTC+1, Celejar a écrit :
[...]
> 1) Why does VLC default to the lower resolution? Incidentally, I see 
> that Cheese also opens the camera by default at a lower resolution - 
> but a different one: 960x540. Why? Is this to save space when recording? 

to set up the default video resolution of your webcam in Cheese, install dconf editor, launch it and set up the the video-x-resolution and video-y-resolution in /org/gnome/cheese/

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#230167

On Wed, 30 Dec 2020 11:02:31 -0800 (PST)
didier gaumet <didier.gaumet@gmail.com> wrote:

> Le mercredi 30 décembre 2020 à 16:40:06 UTC+1, Celejar a écrit :
> [...]
> > 1) Why does VLC default to the lower resolution? Incidentally, I see 
> > that Cheese also opens the camera by default at a lower resolution - 
> > but a different one: 960x540. Why? Is this to save space when recording? 
> 
> to set up the default video resolution of your webcam in Cheese, install dconf editor, launch it and set up the the video-x-resolution and video-y-resolution in /org/gnome/cheese/

Thanks. Once I set it once, the setting seems to survive restarts of
the program, and I'm currently only using Cheese for testing anyway ;)

Celejar

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#230173

Hi Celejar,

To find out the capabilities of your camera, you can install v4l-utils 
and execute:
v4l2-ctl --list-devices
v4l2-ctl -d /dev/video0 --list-formats
v4l2-ctl -d /dev/video0 --list-formats-ext
Check also the other /dev/video* files.

Another method is to use qv4l2 (provided by the homonym package), which 
is very user-friendly and I think it uses v4l2-ctl to find information.

The above information comes from 
https://wiki.archlinux.org/index.php/webcam_setup.

Cheese and vlc must not be used to find out available resolutions.  On 
my Dell built-in webcam both show 640x480 and below, whereas my camera 
supports 1280x720, as given by the laptop specification and 
v4l2-ctl/qv4l2.  As about why do these applications use this resolution, 
I do not have any idea.

Best regards.

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#230192

On Thu, 31 Dec 2020 21:48:33 +0100
Eugen Dedu <eugen.dedu@univ-fcomte.fr> wrote:

> Hi Celejar,
> 
> To find out the capabilities of your camera, you can install v4l-utils 
> and execute:
> v4l2-ctl --list-devices
> v4l2-ctl -d /dev/video0 --list-formats
> v4l2-ctl -d /dev/video0 --list-formats-ext
> Check also the other /dev/video* files.
> 
> Another method is to use qv4l2 (provided by the homonym package), which 
> is very user-friendly and I think it uses v4l2-ctl to find information.

Thanks. I used the lsusb method described here:

https://askubuntu.com/questions/214977/how-can-i-find-out-the-supported-webcam-resolutions

> The above information comes from 
> https://wiki.archlinux.org/index.php/webcam_setup.
> 
> Cheese and vlc must not be used to find out available resolutions.  On 
> my Dell built-in webcam both show 640x480 and below, whereas my camera 
> supports 1280x720, as given by the laptop specification and 
> v4l2-ctl/qv4l2.  As about why do these applications use this resolution, 
> I do not have any idea.

Interesting. On my machine, Cheese does seem to correctly list the
available resolutions.

Thanks again,

Celejar

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