refactor opus bitrate detection

ffprobe.go

@@ -0,0 +1,98 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"os/exec"
+	"strconv"
+	"strings"
+)
+
+type FFProbeOutput struct {
+	Streams []struct {
+		CodecName string `json:"codec_name"`
+	} `json:"streams"`
+}
+
+// runs ffprobe with the provided args and returns (stdout, stderr, error)
+func runFfprobe(args []string) ([]byte, []byte, error) {
+	ffprobe := "ffprobe"
+
+	fmt.Println(ffprobe, strings.Join(args, " "))
+	cmd := exec.Command(ffprobe, args...)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	err := cmd.Run()
+	if err != nil {
+		fmt.Println("ffprobe error:", err, stdout.String(), stderr.String())
+	}
+	return stdout.Bytes(), stderr.Bytes(), err
+}
+
+func getAudioFormat(filename string) (string, error) {
+	output, _, err := runFfprobe([]string{"-v", "quiet", "-print_format", "json", "-show_streams", filename})
+	if err != nil {
+		return "", fmt.Errorf("ffprobe execution failed: %v", err)
+	}
+
+	var ffprobeOutput FFProbeOutput
+	err = json.Unmarshal(output, &ffprobeOutput)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse ffprobe output: %v", err)
+	}
+
+	numStreams := len(ffprobeOutput.Streams)
+	if numStreams > 1 || numStreams <= 0 {
+		return "", fmt.Errorf("%d streams in ffprobe output", numStreams)
+	}
+
+	return ffprobeOutput.Streams[0].CodecName, nil
+}
+
+func getStreamBitrate(path string, stream int) (uint, error) {
+	ffprobeArgs := []string{
+		"-v", "quiet",
+		"-select_streams", fmt.Sprintf("a:%d", stream),
+		"-show_entries", "stream=bit_rate",
+		"-of", "default=noprint_wrappers=1:nokey=1",
+		path}
+
+	stdout, _, err := runFfprobe(ffprobeArgs)
+	if err != nil {
+		fmt.Println("getAudioBitrate error:", err, string(stdout))
+		return 0, err
+	}
+	bitrateStr := strings.TrimSpace(string(stdout))
+
+	bitrate, err := strconv.ParseUint(bitrateStr, 10, 32)
+	if err != nil {
+		fmt.Println("getAudioBitrate error:", err)
+		return 0, err
+	}
+	return uint(bitrate), nil
+}
+
+func getFormatBitrate(path string) (uint, error) {
+	ffprobeArgs := []string{
+		"-v", "quiet",
+		"-show_entries", "format=bit_rate",
+		"-of", "default=noprint_wrappers=1:nokey=1",
+		path}
+
+	stdout, _, err := runFfprobe(ffprobeArgs)
+	if err != nil {
+		fmt.Println("getFormatBitrate error:", err, string(stdout))
+		return 0, err
+	}
+	bitrateStr := strings.TrimSpace(string(stdout))
+
+	bitrate, err := strconv.ParseUint(bitrateStr, 10, 32)
+	if err != nil {
+		fmt.Println("getFormatBitrate error:", err)
+		return 0, err
+	}
+	return uint(bitrate), nil
+}

handlers.go

@@ -3,7 +3,6 @@ package main
 import (
 	"bytes"
 	"fmt"
-	"math"
 	"net/http"
 	"os"
 	"os/exec"
@@ -387,47 +386,15 @@ func getAudioDuration(path string) (float64, error) {
 }
 
 func getAudioBitrate(path string) (uint, error) {
-
-	ffprobe := "ffprobe"
-	ffprobeArgs := []string{
-		"-v", "quiet",
-		"-select_streams", "a:0",
-		"-show_entries", "stream=bit_rate",
-		"-of", "default=noprint_wrappers=1:nokey=1",
-		path}
-
-	fmt.Println(ffprobe, strings.Join(ffprobeArgs, " "))
-	cmd := exec.Command(ffprobe, ffprobeArgs...)
-	var stdout bytes.Buffer
-	cmd.Stdout = &stdout
-	err := cmd.Run()
+	codec, err := getAudioFormat(path)
 	if err != nil {
-		fmt.Println("getAudioBitrate error:", err, stdout.String())
 		return 0, err
 	}
-	bitrateStr := strings.TrimSpace(stdout.String())
-
-	// for opus files, or other files with variable birates, this may come back "N/A"
-
-	if bitrateStr == "N/A" {
-		size, err := getSize(path)
-		if err != nil {
-			return 0, err
-		}
-		dur, err := getAudioDuration(path)
-		if err != nil {
-			return 0, err
-		}
-		return uint(math.Round(float64(size) / dur)), nil
+	if codec == "opus" {
+		return getFormatBitrate(path)
 	} else {
-		bitrate, err := strconv.ParseUint(bitrateStr, 10, 32)
-		if err != nil {
-			fmt.Println("getAudioBitrate error:", err)
-			return 0, err
-		}
-		return uint(bitrate), nil
+		return getStreamBitrate(path, 0)
 	}
-
 }
 
 func getAudioMeta(path string) (AudioMeta, error) {