mirror of https://bitbucket.org/ausocean/av.git
135 lines
3.0 KiB
Go
135 lines
3.0 KiB
Go
/*
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DESCRIPTION
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webcam.go provides an implementation of AVDevice for webcams.
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AUTHORS
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Saxon A. Nelson-Milton <saxon@ausocean.org>
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LICENSE
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Copyright (C) 2019 the Australian Ocean Lab (AusOcean)
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It is free software: you can redistribute it and/or modify them
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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It is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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in gpl.txt. If not, see http://www.gnu.org/licenses.
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*/
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package revid
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import (
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"errors"
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"fmt"
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"io"
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"os/exec"
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"strings"
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"bitbucket.org/ausocean/utils/logger"
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)
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const (
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defaultWebcamInputPath = "/dev/video0"
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defaultWebcamFrameRate = 25
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defaultWebcamBitrate = 400
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defaultWebcamWidth = 1280
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defaultWebcamHeight = 720
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)
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var (
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errWebcamBadFrameRate = errors.New("frame rate bad or unset, defaulting")
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errWebcamBadBitrate = errors.New("bitrate bad or unset, defaulting")
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errWebcamWidth = errors.New("width bad or unset, defaulting")
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errWebcamHeight = errors.New("height bad or unset, defaulting")
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)
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type Webcam struct {
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out io.ReadCloser
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log Logger
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cfg Config
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cmd *exec.Cmd
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}
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func NewWebcam(l Logger) *Webcam {
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return &Webcam{log: l}
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}
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func (w *Webcam) Set(c Config) error {
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var errs []error
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if c.Width == 0 {
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errs = append(errs, errBadWidth)
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c.Width = raspividDefaultWidth
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}
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if c.Height == 0 {
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errs = append(errs, errBadHeight)
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c.Height = raspividDefaultHeight
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}
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if c.FrameRate == 0 {
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errs = append(errs, errBadFrameRate)
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c.FrameRate = raspividDefaultFramerate
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}
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if c.Bitrate <= 0 {
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errs = append(errs, errBadBitrate)
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c.Bitrate = raspividDefaultBitrate
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}
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w.cfg = c
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return multiError(errs)
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}
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func (w *Webcam) Start() error {
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args := []string{
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"-i", w.cfg.InputPath,
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"-f", "h264",
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"-r", fmt.Sprint(w.cfg.FrameRate),
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}
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br := w.cfg.Bitrate * 1000
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args = append(args,
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"-b:v", fmt.Sprint(br),
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"-maxrate", fmt.Sprint(br),
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"-bufsize", fmt.Sprint(br/2),
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"-s", fmt.Sprintf("%dx%d", w.cfg.Width, w.cfg.Height),
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"-",
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)
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w.log.Log(logger.Info, pkg+"ffmpeg args", "args", strings.Join(args, " "))
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w.cmd = exec.Command("ffmpeg", args...)
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var err error
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w.out, err = w.cmd.StdoutPipe()
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if err != nil {
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return fmt.Errorf("failed to create pipe: %w", err)
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}
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err = w.cmd.Start()
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if err != nil {
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return fmt.Errorf("failed to start ffmpeg: %w", err)
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}
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return nil
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}
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func (w *Webcam) Stop() error {
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if w.cmd == nil || w.cmd.Process == nil {
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return errors.New("raspivid process was never started")
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}
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err := w.cmd.Process.Kill()
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if err != nil {
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return fmt.Errorf("could not kill raspivid process: %w", err)
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}
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return w.out.Close()
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}
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func (w *Webcam) Read(p []byte) (int, error) {
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return w.out.Read(p)
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}
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