mirror of
https://github.com/asticode/go-astiav.git
synced 2025-10-05 00:02:45 +08:00
Added software resample context
This commit is contained in:
Quentin Renard
295
examples/resampling_audio/main.go
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295
examples/resampling_audio/main.go
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@@ -0,0 +1,295 @@
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package main
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import (
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"errors"
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"flag"
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"fmt"
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"log"
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"strings"
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"github.com/asticode/go-astiav"
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)
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var (
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input = flag.String("i", "", "the input path")
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)
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var (
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af *astiav.AudioFifo
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finalFrame *astiav.Frame
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resampledFrame *astiav.Frame
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src *astiav.SoftwareResampleContext
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decodedFrame *astiav.Frame
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)
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func main() {
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// Handle ffmpeg logs
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astiav.SetLogLevel(astiav.LogLevelDebug)
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astiav.SetLogCallback(func(c astiav.Classer, l astiav.LogLevel, fmt, msg string) {
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var cs string
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if c != nil {
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if cl := c.Class(); cl != nil {
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cs = " - class: " + cl.String()
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}
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}
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log.Printf("ffmpeg log: %s%s - level: %d\n", strings.TrimSpace(msg), cs, l)
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})
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// Parse flags
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flag.Parse()
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// Usage
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if *input == "" {
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log.Println("Usage: <binary path> -i <input path>")
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return
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}
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// Allocate input format context
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inputFormatContext := astiav.AllocFormatContext()
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if inputFormatContext == nil {
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log.Fatal(errors.New("main: input format context is nil"))
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}
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defer inputFormatContext.Free()
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// Open input
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if err := inputFormatContext.OpenInput(*input, nil, nil); err != nil {
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log.Fatal(fmt.Errorf("main: opening input failed: %w", err))
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}
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defer inputFormatContext.CloseInput()
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// Find stream info
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if err := inputFormatContext.FindStreamInfo(nil); err != nil {
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log.Fatal(fmt.Errorf("main: finding stream info failed: %w", err))
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}
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// Loop through streams
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var s *astiav.Stream
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var cc *astiav.CodecContext
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for _, is := range inputFormatContext.Streams() {
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// Only process audio
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if is.CodecParameters().MediaType() != astiav.MediaTypeAudio {
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continue
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}
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// Store stream
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s = is
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// Find decoder
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c := astiav.FindDecoder(is.CodecParameters().CodecID())
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if c == nil {
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log.Fatal(errors.New("main: codec is nil"))
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}
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// Allocate codec context
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if cc = astiav.AllocCodecContext(c); cc == nil {
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log.Fatal(errors.New("main: codec context is nil"))
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}
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defer cc.Free()
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// Update codec context
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if err := is.CodecParameters().ToCodecContext(cc); err != nil {
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log.Fatal(fmt.Errorf("main: updating codec context failed: %w", err))
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}
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// Open codec context
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if err := cc.Open(c, nil); err != nil {
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log.Fatal(fmt.Errorf("main: opening codec context failed: %w", err))
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}
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break
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}
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// No stream
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if s == nil {
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log.Fatal("main: no audio stream found")
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}
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// Alloc resample context
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src = astiav.AllocSoftwareResampleContext()
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defer src.Free()
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// Allocate packet
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pkt := astiav.AllocPacket()
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defer pkt.Free()
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// Allocate decoded frame
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decodedFrame = astiav.AllocFrame()
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defer decodedFrame.Free()
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// Allocate resampled frame
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resampledFrame = astiav.AllocFrame()
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defer resampledFrame.Free()
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// For the resampled frame we need to setup mandatory information
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resampledFrame.SetChannelLayout(astiav.ChannelLayoutStereo)
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resampledFrame.SetSampleFormat(astiav.SampleFormatFltp)
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resampledFrame.SetSampleRate(24000)
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// Do this only if you want to make sure the resampled frame's number of samples doesn't get
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// bigger than a custom value ("200" in our case)
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resampledFrame.SetNbSamples(200)
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const align = 0
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if err := resampledFrame.AllocBuffer(align); err != nil {
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log.Fatal(fmt.Errorf("main: allocating buffer failed: %w", err))
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}
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if err := resampledFrame.AllocSamples(align); err != nil {
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log.Fatal(fmt.Errorf("main: allocating samples failed: %w", err))
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}
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// Do this only if you want to make sure final frames have an exact constant number of samples
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// In that case we use an audio FIFO
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finalFrame = astiav.AllocFrame()
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defer finalFrame.Free()
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finalFrame.SetChannelLayout(resampledFrame.ChannelLayout())
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finalFrame.SetNbSamples(resampledFrame.NbSamples())
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finalFrame.SetSampleFormat(resampledFrame.SampleFormat())
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finalFrame.SetSampleRate(resampledFrame.SampleRate())
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if err := finalFrame.AllocBuffer(align); err != nil {
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log.Fatal(fmt.Errorf("main: allocating buffer failed: %w", err))
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}
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if err := finalFrame.AllocSamples(align); err != nil {
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log.Fatal(fmt.Errorf("main: allocating samples failed: %w", err))
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}
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af = astiav.AllocAudioFifo(finalFrame.SampleFormat(), finalFrame.ChannelLayout().Channels(), finalFrame.NbSamples())
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defer af.Free()
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// Loop
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for {
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// We use a closure to ease unreferencing the packet
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if stop := func() bool {
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// Read frame
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if err := inputFormatContext.ReadFrame(pkt); err != nil {
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if errors.Is(err, astiav.ErrEof) {
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return true
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}
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log.Fatal(fmt.Errorf("main: reading frame failed: %w", err))
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}
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// Make sure to unreference the packet
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defer pkt.Unref()
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// Invalid stream
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if pkt.StreamIndex() != s.Index() {
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return false
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}
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// Send packet
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if err := cc.SendPacket(pkt); err != nil {
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log.Fatal(fmt.Errorf("main: sending packet failed: %w", err))
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}
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// Loop
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for {
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// We use a closure to ease unreferencing the frame
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if stop := func() bool {
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// Receive frame
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if err := cc.ReceiveFrame(decodedFrame); err != nil {
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if errors.Is(err, astiav.ErrEof) || errors.Is(err, astiav.ErrEagain) {
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return true
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}
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log.Fatal(fmt.Errorf("main: receiving frame failed: %w", err))
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}
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// Make sure to unreference the frame
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defer decodedFrame.Unref()
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// Log
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log.Printf("new decoded frame: nb samples: %d", decodedFrame.NbSamples())
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// Resample decoded frame
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if err := src.ConvertFrame(decodedFrame, resampledFrame); err != nil {
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log.Fatal(fmt.Errorf("main: resampling decoded frame failed: %w", err))
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}
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// Something was resampled
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if nbSamples := resampledFrame.NbSamples(); nbSamples > 0 {
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// Log
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log.Printf("new resampled frame: nb samples: %d", nbSamples)
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// Add resampled frame to audio fifo
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if err := addResampledFrameToAudioFIFO(false); err != nil {
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log.Fatal(fmt.Errorf("main: adding resampled frame to audio fifo failed: %w", err))
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}
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// Flush software resample context
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if err := flushSoftwareResampleContext(false); err != nil {
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log.Fatal(fmt.Errorf("main: flushing software resample context failed: %w", err))
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}
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}
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return false
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}(); stop {
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break
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}
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}
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return false
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}(); stop {
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break
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}
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}
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// Flush software resample context
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if err := flushSoftwareResampleContext(true); err != nil {
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log.Fatal(fmt.Errorf("main: flushing software resample context failed: %w", err))
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}
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// Success
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log.Println("success")
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}
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func flushSoftwareResampleContext(finalFlush bool) error {
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// Loop
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for {
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// We're making the final flush or there's enough data to flush the resampler
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if finalFlush || src.Delay(int64(resampledFrame.SampleRate())) >= int64(resampledFrame.NbSamples()) {
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// Flush resampler
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if err := src.ConvertFrame(nil, resampledFrame); err != nil {
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log.Fatal(fmt.Errorf("main: flushing resampler failed: %w", err))
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}
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// Log
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if resampledFrame.NbSamples() > 0 {
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log.Printf("new resampled frame: nb samples: %d", resampledFrame.NbSamples())
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}
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// Add resampled frame to audio fifo
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if err := addResampledFrameToAudioFIFO(finalFlush); err != nil {
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log.Fatal(fmt.Errorf("main: adding resampled frame to audio fifo failed: %w", err))
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}
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// Final flush is done
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if finalFlush && resampledFrame.NbSamples() == 0 {
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break
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}
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continue
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}
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break
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}
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return nil
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}
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func addResampledFrameToAudioFIFO(flush bool) error {
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// Write
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if resampledFrame.NbSamples() > 0 {
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if _, err := af.Write(resampledFrame); err != nil {
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return fmt.Errorf("main: writing failed: %w", err)
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}
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}
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// Loop
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for {
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// We're flushing or there's enough data to read
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if (flush && af.Size() > 0) || (!flush && af.Size() >= finalFrame.NbSamples()) {
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// Read
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n, err := af.Read(finalFrame)
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if err != nil {
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return fmt.Errorf("main: reading failed: %w", err)
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}
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finalFrame.SetNbSamples(n)
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// Log
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log.Printf("new final frame: nb samples: %d", finalFrame.NbSamples())
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continue
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}
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break
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}
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return nil
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}
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