mirror of https://bitbucket.org/ausocean/av.git
111 lines
2.8 KiB
Go
111 lines
2.8 KiB
Go
/*
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DESCRIPTION
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file.go provides an implementation of the AVDevice interface for media files.
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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 file provides an implementation of AVDevice for files.
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package file
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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"
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"bitbucket.org/ausocean/av/revid/config"
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)
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// AVFile is an implementation of the AVDevice interface for a file containg
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// audio or video data.
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type AVFile struct {
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f *os.File
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cfg config.Config
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isRunning bool
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}
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// NewAVFile returns a new AVFile.
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func New() *AVFile { return &AVFile{} }
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// Name returns the name of the device.
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func (m *AVFile) Name() string {
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return "File"
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}
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// Set simply sets the AVFile's config to the passed config.
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func (m *AVFile) Set(c config.Config) error {
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m.cfg = c
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return nil
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}
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// Start will open the file at the location of the InputPath field of the
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// config struct.
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func (m *AVFile) Start() error {
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var err error
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m.f, err = os.Open(m.cfg.InputPath)
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if err != nil {
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return fmt.Errorf("could not open media file: %w", err)
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}
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m.isRunning = true
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return nil
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}
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// Stop will close the file such that any further reads will fail.
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func (m *AVFile) Stop() error {
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err := m.f.Close()
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if err == nil {
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m.isRunning = false
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return nil
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}
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return err
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}
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// Read implements io.Reader. If start has not been called, or Start has been
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// called and Stop has since been called, an error is returned.
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func (m *AVFile) Read(p []byte) (int, error) {
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if m.f != nil {
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n, err := m.f.Read(p)
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if err != nil {
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// In the case that we reach end of file but loop is true, we want to
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// seek to start and keep reading from there.
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if err == io.EOF && m.cfg.Loop {
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_, err = m.f.Seek(0, io.SeekStart)
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if err != nil {
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return 0, fmt.Errorf("could not seek to start of file for input loop: %w", err)
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}
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// Now that we've seeked to start, let's try reading again.
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n, err = m.f.Read(p)
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if err != nil {
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return n, fmt.Errorf("could not read after start seek: %w", err)
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}
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}
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}
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return n, err
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}
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return 0, errors.New("AV file is closed")
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}
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// IsRunning is used to determine if the AVFile device is running.
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func (m *AVFile) IsRunning() bool {
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return m.f != nil && m.isRunning
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}
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