Added encode example

Author: djthorpe

README.md

@@ -104,7 +104,7 @@ func main() {
 }
 ```
 
-### Decoding - Video Frames
+### Decoding - Video
 
 This example shows you how to decode video frames from a media file into images.
 
@@ -156,9 +156,75 @@ func main() {
 }
 ```
 
-### Encoding
+### Encoding - Audio and Video
 
-TODO
+This example shows you how to encode video and audio frames into a media file.
+
+```go
+package main
+
+import (
+  "io"
+  "log"
+  "os"
+  "time"
+
+  media "github.com/mutablelogic/go-media"
+  ffmpeg "github.com/mutablelogic/go-media/pkg/ffmpeg"
+  generator "github.com/mutablelogic/go-media/pkg/generator"
+  ff "github.com/mutablelogic/go-media/sys/ffmpeg61"
+)
+
+func main() {
+  // Create a new file with an audio and video stream
+  // 30fps and 22050Hz mono audio
+  file, err := ffmpeg.Create(os.Args[1],
+    ffmpeg.OptStream(1, ffmpeg.VideoPar("yuv420p", "640x480", 30)),
+    ffmpeg.OptStream(2, ffmpeg.AudioPar("fltp", "mono", 22050)),
+  )
+  if err != nil {
+    log.Fatal(err)
+  }
+  defer file.Close()
+
+  // Make an video generator which can generate YUV420P frames
+  // with the same parameters as the video stream
+  video, err := generator.NewYUV420P(file.Stream(1).Par())
+  if err != nil {
+    log.Fatal(err)
+  }
+  defer video.Close()
+
+  // Make an audio generator which can generate a 440Hz tone
+  // at -5dB with the same parameters as the audio stream
+  audio, err := generator.NewSine(440, -5, file.Stream(2).Par())
+  if err != nil {
+    log.Fatal(err)
+  }
+  defer audio.Close()
+
+  // Write 1 min of frames, passing video and audio frames to the encoder
+  // and returning io.EOF when the duration is reached
+  duration := time.Minute
+  if err := file.Encode(func(stream int) (*ff.AVFrame, error) {
+    var frame media.Frame
+    switch stream {
+    case 1:
+      frame = video.Frame()
+    case 2:
+      frame = audio.Frame()
+    }
+    if frame.Time() >= duration {
+      return nil, io.EOF
+    } else {
+      log.Println("Frame", stream, "=>", frame.Time().Truncate(time.Millisecond))
+      return frame.(*ffmpeg.Frame).AVFrame(), nil
+    }
+  }, nil); err != nil {
+    log.Fatal(err)
+  }
+}
+```
 
 ### Multiplexing
 

cmd/examples/encode/main.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"io"
+	"log"
+	"os"
+	"time"
+
+	media "github.com/mutablelogic/go-media"
+	ffmpeg "github.com/mutablelogic/go-media/pkg/ffmpeg"
+	generator "github.com/mutablelogic/go-media/pkg/generator"
+	ff "github.com/mutablelogic/go-media/sys/ffmpeg61"
+)
+
+func main() {
+	// Create a new file with an audio and video stream
+	file, err := ffmpeg.Create(os.Args[1],
+		ffmpeg.OptStream(1, ffmpeg.VideoPar("yuv420p", "640x480", 30)),
+		ffmpeg.OptStream(2, ffmpeg.AudioPar("fltp", "mono", 22050)),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer file.Close()
+
+	// Make an video generator which can generate YUV420P frames
+	// with the same parameters as the video stream
+	video, err := generator.NewYUV420P(file.Stream(1).Par())
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer video.Close()
+
+	// Make an audio generator which can generate a 440Hz tone
+	// at -5dB with the same parameters as the audio stream
+	audio, err := generator.NewSine(440, -5, file.Stream(2).Par())
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer audio.Close()
+
+	// Write 1 min of frames, passing video and audio frames to the encoder
+	// and returning io.EOF when the duration is reached
+	duration := time.Minute
+	if err := file.Encode(func(stream int) (*ff.AVFrame, error) {
+		var frame media.Frame
+		switch stream {
+		case 1:
+			frame = video.Frame()
+		case 2:
+			frame = audio.Frame()
+		}
+		if frame.Time() >= duration {
+			return nil, io.EOF
+		} else {
+			log.Println("Frame", stream, "=>", frame.Time().Truncate(time.Millisecond))
+			return frame.(*ffmpeg.Frame).AVFrame(), nil
+		}
+	}, nil); err != nil {
+		log.Fatal(err)
+	}
+}