74 lines
1.9 KiB
Go
74 lines
1.9 KiB
Go
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// Helper functions for extracting pcm audio from web and local sources.
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package dca0
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import (
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"errors"
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"io"
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"os/exec"
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"strconv"
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)
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type PcmOptions struct {
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FfmpegPath string
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Channels int
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SampleRate int
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// Seek means where to start in seconds.
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Seek float32
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// Duration means where to stop (in seconds after the time specified by Seek).
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// If Duration is set to 0, the stream will ignore it and encode all the way
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// to the end of the input.
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Duration float32
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}
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func getDefaultPcmOptions(ffmpegPath string) PcmOptions {
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return PcmOptions{
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FfmpegPath: ffmpegPath,
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Channels: 2,
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// 48000 is the only one used by discord currently.
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SampleRate: 48000,
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Seek: 0,
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Duration: 0,
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}
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}
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// Input can be either a local file or an http(s) address. It can be of any
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// audio format supported by ffmpeg.
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// Wait must be called on the returned command to free its resources after
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// everything has been read.
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func getPcm(input string, opts PcmOptions) (io.ReadCloser, *exec.Cmd, error) {
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if input == "" {
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return nil, nil, errors.New("dca0.getPcm() called with empty input")
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}
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var cmdOpts []string
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cmdOpts = append(cmdOpts, []string{
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"-vn", // No video.
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"-sn", // No subtitle.
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"-dn", // No data encoding.
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}...)
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if opts.Seek != 0.0 {
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cmdOpts = append(cmdOpts,
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"-accurate_seek",
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"-ss", strconv.FormatFloat(float64(opts.Seek), 'f', 5, 32))
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}
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if opts.Duration != 0.0 {
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cmdOpts = append(cmdOpts,
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"-t", strconv.FormatFloat(float64(opts.Duration), 'f', 5, 32))
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}
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cmdOpts = append(cmdOpts, []string{
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"-i", input,
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"-f", "s16le", // Signed int16 samples.
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"-ar", strconv.Itoa(opts.SampleRate),
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"-ac", strconv.Itoa(opts.Channels), // Number of audio channels.
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"pipe:1", // Output to stdout.
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}...)
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cmd := exec.Command(opts.FfmpegPath, cmdOpts...)
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stdout, err := cmd.StdoutPipe()
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if err != nil {
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return nil, nil, err
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}
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if err := cmd.Start(); err != nil {
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return nil, nil, err
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}
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return stdout, cmd, nil
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}
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