[FFmpeg-user] All the video captures are made at a resolution of 176x144

DiegoUG diego.uribe.gamez at gmail.com
Wed Feb 28 01:00:32 EET 2018

2018-02-27 8:58 GMT-05:00 Moritz Barsnick <barsnick at gmx.net>:

> On Mon, Feb 26, 2018 at 16:43:50 -0500, Lindsey Williams wrote:
> > "-r 1 " is just going to use the input file sampling rate, no?
> Input file? We are talking about an input device (as this is a camera),
> and the term is "frame rate". "-r" should be "-framerate" for a v4l2
> input, but "-r" works. It requests the driver to provide this
> framerate. The original poster used this in their command line.
> > "You need to check with V4L utilities or ffmpeg, which formats /
> > resolutions your v4l2 device provides. I would guess that docker gives
> you
> > only an abstraction (it's a kind of virtualization, right?)."
> >
> > Agree with that.  Cameras are getting smaller and smaller.... and in
> order
> > to get away with that software is used on the the intake signal and
> > unwrapped/decompressed into larger resolutions as it goes to our screens.
> But physically, they provide a certain resolution via the wire. (Only
> the cra**y Windows drivers or apps upscale automatically, fooling the
> user into thinking there's a larger resolution, as printed on the box.
> But we're talking Linux here - no such issue from
> ffmpeg's/video4linux's point of view.)
> > The reason I suggested scaling is because you didn't complain about the
> > image not making sense... which means ffmpeg was able to decode the
> stream
> > and encode it into some format ( maybe not the ideal one. )
> No, the issue the original poster was complaining about was that the
> camera delivers the desired resolution perfectly when accessing it from
> the bare operating system. When operating from with a docker container
> (some sort of virtualization) on the same machine, the device driver
> only presents a lower resolution. My guess: Either the default is
> different inside the docker, or the "virtualization" doesn't pass on
> the camera's full feature set, for whatever reason.

Yes Moritz Barsnick, one thing that can be seen in the commands that I
place, where I show a list of the resolutions that the device supports in
my localhost, detects that yuyv422 in my local takes the maximum resolution
is 1280x720 but in the container it is 176x144 and the other curious thing
is that inside the container appears another format that has the resolution
of 1280x720, and that is that I do not have a deep knowledge of ffmpeg to
use the mjpeg or h264 format and take the photo at the maximum resolution
inside the container.

Docker ------------------------------------------------------------
# ffmpeg -f v4l2 -list_formats all -i /dev/video0
[video4linux2,v4l2 @ 0x55e122701f60] Raw       :     yuyv422 :
 YUYV 4:2:2 : 160x90 160x120 176x144
[video4linux2,v4l2 @ 0x55e122701f60] Compressed:        h264 :
  H.264 : 640x480 160x90 160x120 176x144 320x180 320x240 352x288 432x240
640x360 800x448 800x600 864x480 960x720 1024x576 1280x720
[video4linux2,v4l2 @ 0x55e122701f60] Compressed:       mjpeg :
Motion-JPEG : 640x480 160x90 160x120 176x144 320x180 320x240 352x288
432x240 640x360

local ------------------------------------------------------
# ffmpeg -f v4l2 -list_formats all -i /dev/video0

[video4linux2,v4l2 @ 0x55b84fec19c0] Raw       :     yuyv422 :
 YUYV 4:2:2 : 640x480 320x180 320x240 352x288 424x240 640x360 848x480
960x540 1280x720
[video4linux2,v4l2 @ 0x55b84fec19c0] Compressed:       mjpeg :
Motion-JPEG : 640x480 320x180 320x240 352x288 424x240 640x360 848x480
960x540 1280x720


> Moritz
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  *Diego Alonso Uribe Gamez*

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