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113 lines
2.7 KiB
Go
113 lines
2.7 KiB
Go
package customsrc
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import (
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"fmt"
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"log"
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"math"
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"time"
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"github.com/go-gst/go-glib/pkg/gobject/v2"
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"github.com/go-gst/go-gst/pkg/gst"
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)
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// default: 1024, this value makes it easier to calculate num buffers with the sample rate
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const samplesperbuffer = 4800
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const samplerate = 48000
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func classInit(class *gst.BinClass) {
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class.ParentClass().SetStaticMetadata(
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"custom test source",
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"Src/Test",
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"Demo source bin with volume",
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"Wilhelm Bartel <bartel.wilhelm@gmail.com>",
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)
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class.ParentClass().AddPadTemplate(gst.NewPadTemplate(
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"src",
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gst.PadSrc,
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gst.PadAlways,
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gst.CapsFromString(fmt.Sprintf("audio/x-raw,channels=2,rate=%d", samplerate)),
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))
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class.ParentClass().ParentClass().ParentClass().ParentClass().InstallProperties([]*gobject.ParamSpec{
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gobject.ParamSpecInt64(
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"duration",
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"duration",
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"Duration of the source in nanoseconds",
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0,
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math.MaxInt64,
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0,
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gobject.ParamReadwrite|gobject.ParamConstruct),
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})
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}
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type customSrc struct {
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gst.BinInstance // parent must be embedded as the first field
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source gst.Element
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volume gst.Element
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Duration time.Duration
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}
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// InstanceInit should initialize the element. Keep in mind that the properties are not yet present. When this is called.
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func (bin *customSrc) init() {
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bin.source = gst.ElementFactoryMakeWithProperties("audiotestsrc", map[string]any{
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"samplesperbuffer": samplesperbuffer,
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})
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bin.volume = gst.ElementFactoryMake("volume", "")
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bin.AddMany(
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bin.source,
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bin.volume,
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)
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srcpad := bin.volume.GetStaticPad("src")
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ghostpad := gst.NewGhostPadFromTemplate("src", srcpad, bin.GetPadTemplate("src"))
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gst.LinkMany(
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bin.source,
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bin.volume,
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)
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bin.AddPad(ghostpad)
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bin.updateSource()
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}
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func (bin *customSrc) setProperty(_ uint, value any, pspec *gobject.ParamSpec) {
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switch pspec.Name() {
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case "duration":
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bin.Duration = time.Duration(value.(int64)) // declared as int64 property in classInit
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log.Printf("set duration to %s", bin.Duration)
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bin.updateSource()
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default:
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panic("unknown property")
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}
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}
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func (bin *customSrc) getProperty(_ uint, pspec *gobject.ParamSpec) any {
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switch pspec.Name() {
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case "duration":
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return int64(bin.Duration) // declared as int64 property in classInit
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default:
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panic("unknown property")
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}
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}
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// updateSource will get called to update the audiotestsrc when a property changes
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func (s *customSrc) updateSource() {
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if s.source == nil {
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// the construct param may be set before we initialized the source
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return
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}
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numBuffers := (float64(s.Duration / time.Second)) / (float64(samplesperbuffer) / float64(samplerate))
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s.source.SetObjectProperty("num-buffers", int32(math.Ceil(numBuffers)))
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log.Printf("set num-buffers to %d", int(math.Ceil(numBuffers)))
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}
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