Skip to content

Commit

Permalink
Added image capturing and text drawing.
Browse files Browse the repository at this point in the history
  • Loading branch information
@interkosmos
interkosmos committed Oct 19, 2024
1 parent bde5502 commit a56c100
Showing 1 changed file with 211 additions and 24 deletions.
235 changes: 211 additions & 24 deletions src/dm_camera.f90
View file
Original file line number Diff line number Diff line change
@@ -1,12 +1,14 @@
! Author: Philipp Engel
! Licence: ISC
module dm_camera
!! Module for handling IP cameras and webcams using FFmpeg.
!! Module for taking still images from RTSP video streams and USB webcams,
!! using FFmpeg.
!!
!! On Linux, install the packages `ffmpeg` and `v4l-utils`:
!! On Linux, install the packages `ffmpeg`, `graphicsmagick`, and
!! `v4l-utils`:
!!
!! ```
!! $ sudo apt-get install ffmpeg v4l-utils
!! $ sudo apt-get install ffmpeg graphicsmagick v4l-utils
!! ```
!!
!! List connected USB cameras:
Expand All @@ -19,37 +21,222 @@ module dm_camera
!! /dev/media0
!! ```
!!
!! Capture a still image from the camera attached to `/dev/video0`, add a
!! timestamp to the bottom right corner, and save it to `/tmp/image.jpg`:
!! GraphicsMagick is required to add text to captured camera frames. For a
!! list of all supported font names, run:
!!
!! ```
!! $ ffmpeg -f video4linux2 -i /dev/video0 -vframes 1 -video_size 640x480 \
!! -vf "drawtext=fontfile=DejaVuMono.ttf:fontsize=12:fontcolor=white:box=1:boxcolor=black:text='%{localtime}':x=(w-text_w):y=(h-text_h)" \
!! -hide_banner -loglevel error -nostats -y \
!! /tmp/image.jpg
!! $ gm convert -list font
!! Path: /usr/local/lib/GraphicsMagick/config/type-windows.mgk
!!
!! Name Family Style Stretch Weight
!! --------------------------------------------------------------------------------
!! Arial Arial normal normal 400
!! Arial-Black Arial normal normal 900
!! Arial-Bold Arial normal normal 700
!! Arial-Bold-Italic Arial italic normal 700
!! Arial-Italic Arial italic normal 400
!! ...
!! ```
!!
!! The default font used is `Lucida-Console` in 12 points size.
!!
!! The following example captures an image from an attached USB webcam at
!! `/dev/video0` and adds a timestamp in ISO 8601 to it:
!!
!! ```fortran
!! character(len=*), parameter :: IMAGE_PATH = '/tmp/image.jpg'
!!
!! integer :: rc
!! type(camera_type) :: camera
!!
!! camera = camera_type(input='/dev/video0', device=CAMERA_DEVICE_V4L)
!!
!! rc = dm_camera_capture(camera, IMAGE_PATH)
!! if (dm_is_error(rc)) call dm_error_out(rc)
!!
!! rc = dm_camera_image_add_text(IMAGE_PATH, text=dm_time_now())
!! if (dm_is_error(rc)) call dm_error_out(rc)
!! ```
use :: dm_file, only: FILE_PATH_LEN
use :: dm_mime, only: MIME_LEN, MIME_GIF, MIME_PNG, MIME_JPEG
use :: dm_error
use :: dm_file
use :: dm_string
use :: dm_time
implicit none (type, external)
private

! FFmpeg devices/formats.
integer, parameter, public :: CAMERA_DEVICE_NONE = 0 !! No device selected.
integer, parameter, public :: CAMERA_DEVICE_V4L = 1 !! Video4Linux2.
integer, parameter, public :: CAMERA_DEVICE_RTSP = 2 !! RTSP stream.
integer, parameter, public :: CAMERA_DEVICE_RTSP = 1 !! RTSP stream.
integer, parameter, public :: CAMERA_DEVICE_V4L = 2 !! USB webcam via Video4Linux2.
integer, parameter, public :: CAMERA_DEVICE_LAST = 2 !! Never use this.

integer, parameter, public :: CAMERA_COLOR_LEN = 32 !! Max. length of GM colour name.
integer, parameter, public :: CAMERA_COMMAND_LEN = FILE_PATH_LEN !! Max. length of command string.
integer, parameter, public :: CAMERA_FONT_LEN = 64 !! Max. length of GraphicsMagick font name.
integer, parameter, public :: CAMERA_GRAVITY_LEN = 32 !! Max. length of GM gravity.

integer, parameter, public :: CAMERA_FONT_LEN = 128 !! Max. length of font name or path.
character(len=*), parameter :: CAMERA_FFMPEG = 'ffmpeg' !! FFmpeg binary name.
character(len=*), parameter :: CAMERA_GM = 'gm' !! GraphicsMagick binary name.

type, public :: camera_type
!! Camera context type.
integer :: device = CAMERA_DEVICE_NONE !! Input device.
character(len=FILE_PATH_LEN) :: input = ' ' !! Input path.
character(len=FILE_PATH_LEN) :: output = ' ' !! Output path.
character(len=MIME_LEN) :: mime = ' ' !! Output format (MIME type).
character(len=CAMERA_FONT_LEN) :: font = ' ' !! Overlay font name.
integer :: font_size = 12 !! Overlay font size
integer :: width = 0 !! Image width in pixels.
integer :: height = 0 !! Image size in pixels.
logical :: overlay = .false. !! Overlay flag.
!! Camera settings type.
character(len=FILE_PATH_LEN) :: input = ' ' !! Input device path (`/dev/video0` or `rtsp://10.0.0.1`).
integer :: device = CAMERA_DEVICE_NONE !! Input device.
integer :: width = 0 !! Camera stream width in pixels (optional).
integer :: height = 0 !! Camera stream height in pixels (optional).
end type camera_type

type, public :: camera_text_box_type
!! Text box settings for drawing text onto camera frame image.
character(len=CAMERA_GRAVITY_LEN) :: gravity = 'SouthWest' !! Text position.
character(len=CAMERA_COLOR_LEN) :: background = 'black' !! Box colour.
character(len=CAMERA_COLOR_LEN) :: foreground = 'white' !! Text colour.
character(len=CAMERA_FONT_LEN) :: font = 'Lucida-Console' !! GraphicsMagick font name.
integer :: font_size = 12 !! Font size in points.
end type camera_text_box_type

public :: dm_camera_capture
public :: dm_camera_device_is_valid
public :: dm_camera_image_add_text
public :: dm_camera_prepare_command_ffmpeg
public :: dm_camera_prepare_command_gm
contains
! **************************************************************************
! PUBLIC FUNCTIONS.
! **************************************************************************
integer function dm_camera_capture(camera, output) result(rc)
!! Captures a single frame from a V4L device or RTSP stream with
!! FFmpeg, and optionally adds a timestamp with GraphicsMagick. If the
!! input is an RTSP stream, the URL must start with `rtsp://`.
!!
!! The function returns the following error codes:
!!
!! * `E_EMPTY` if camera input or output is empty.
!! * `E_INVALID` if camera device or RTSP stream URL is invalid.
!! * `E_IO` if FFmpeg command execution failed.
!!
type(camera_type), intent(in) :: camera !! Camera type.
character(len=*), intent(in) :: output !! Output file.

character(len=CAMERA_COMMAND_LEN) :: command
integer :: exit_stat

rc = E_EMPTY
if (len_trim(camera%input) == 0 .or. len_trim(output) == 0) return

rc = E_INVALID
if (.not. dm_camera_device_is_valid(camera%device)) return
if (camera%device == CAMERA_DEVICE_RTSP .and. .not. dm_string_starts_with(camera%input, 'rtsp://')) return

rc = E_IO
call dm_camera_prepare_command_ffmpeg(command, camera, output)
call execute_command_line(trim(command), exitstat=exit_stat)

if (exit_stat /= 0) return
if (.not. dm_file_exists(output)) return

rc = E_NONE
end function dm_camera_capture

logical function dm_camera_device_is_valid(device) result(is)
!! Returns `.true.` if device enumerator is valid. The device
!! `CAMERA_DEVICE_NONE` is invalid.
integer, intent(in) :: device !! Camera device enumerator.

is = (device > CAMERA_DEVICE_NONE .and. device <= CAMERA_DEVICE_LAST)
end function dm_camera_device_is_valid

integer function dm_camera_image_add_text(path, text, box) result(rc)
!! Draws text onto camera image file, using GraphicsMagick. By default,
!! the text box is drawn to the bottom-left corner of the image.
!!
!! The function returns the following error codes:
!!
!! * `E_EMPTY` if text or image path are empty.
!! * `E_IO` if GraphicsMagick command execution failed.
!! * `E_NOT_FOUND` if image at given path does no exist.
!!
character(len=*), intent(in) :: path !! Image file path.
character(len=*), intent(in) :: text !! Text to add.
type(camera_text_box_type), intent(in), optional :: box !! Camera box type.

character(len=CAMERA_COMMAND_LEN) :: command
integer :: exit_stat

rc = E_EMPTY
if (len_trim(path) == 0 .or. len_trim(text) == 0) return

rc = E_NOT_FOUND
if (.not. dm_file_exists(path)) return

rc = E_IO
call dm_camera_prepare_command_gm(command, path, text, box)
call execute_command_line(trim(command), exitstat=exit_stat)
if (exit_stat /= 0) return

rc = E_NONE
end function dm_camera_image_add_text

! **************************************************************************
! PUBLIC SUBROUTINES.
! **************************************************************************
subroutine dm_camera_prepare_command_ffmpeg(command, camera, output)
!! Creates FFmpeg command to capture a single camera frame through V4L
!! or RTSP. The function returns `E_INVALID` on error.
character(len=CAMERA_COMMAND_LEN), intent(out) :: command !! Prepared command string.
type(camera_type), intent(in) :: camera !! Camera type.
character(len=*), intent(in) :: output !! Output file.

character(len=32) :: video_size

! Disable logging and set output file.
command = ' -hide_banner -loglevel fatal -nostats -y ' // output

! Format argument `-f` must be before input argument `-i`.
select case (camera%device)
case (CAMERA_DEVICE_RTSP)
! Capture RTSP stream for 0.5 seconds to get key frame,
! overwrite output file.
command = ' -f image2 -i ' // trim(camera%input) // ' -update 1 -t 0.5' // command

case (CAMERA_DEVICE_V4L)
! Capture single frame from V4L device.
if (camera%width > 0 .and. camera%height > 0) then
write (video_size, '(" -video_size ", i0, "x", i0)') camera%width, camera%height
command = trim(video_size) // command
end if

command = ' -f v4l2 -i ' // trim(camera%input) // ' -frames:v 1' // command
end select

! Concatenate command string.
command = CAMERA_FFMPEG // command
end subroutine dm_camera_prepare_command_ffmpeg

subroutine dm_camera_prepare_command_gm(command, path, text, box)
!! Prepares GraphicsMagick command to add text to image.
character(len=CAMERA_COMMAND_LEN), intent(out) :: command !! Prepared command string.
character(len=*), intent(in) :: path !! Image file path.
character(len=*), intent(in) :: text !! Text to add.
type(camera_text_box_type), intent(in), optional :: box !! Camera box type.

character(len=32) :: point_size
type(camera_text_box_type) :: box_

if (present(box)) box_ = box

write (command, '(" -gravity ", a, " -box ", a, " -fill ", a, " -draw ''text 0,0 """, a, """''", 2(1x, a))') &
trim(box_%gravity), trim(box_%background), trim(box_%foreground), trim(text), trim(path), path

if (box_%font_size > 0) then
write (point_size, '(" -pointsize ", i0)') box_%font_size
command = trim(point_size) // command
end if

if (len_trim(box_%font) > 0) then
command = ' -font ' // trim(box_%font) // command
end if

command = CAMERA_GM // ' convert' // command
end subroutine dm_camera_prepare_command_gm
end module dm_camera

0 comments on commit a56c100

Please sign in to comment.