delete guess expected size feature

it it doing some really bad guesses for opus files

transcode/testdata/fuzz/FuzzGuessExpectedSize/1e10ee326324ee7e1f371585414e7e41d5c802b4db45ebc79abe0397fb915a0c

@@ -1,3 +0,0 @@
-go test fuzz v1
-byte('Y')
-byte('\x05')

transcode/testdata/fuzz/FuzzGuessExpectedSize/3eaed9c9c8a57078033cea3337a79e1e6bfebf7e5eb7421878c911df2d78d1ac

@@ -1,3 +0,0 @@
-go test fuzz v1
-byte('\x15')
-byte('}')

transcode/testdata/fuzz/FuzzGuessExpectedSize/ce5db7c5c16dcb48567255c77772cacc3ca86d524cbb2d3a769248625bc3edc8

@@ -1,3 +0,0 @@
-go test fuzz v1
-byte('\a')
-byte('\x02')

transcode/transcode.go

@@ -15,7 +15,7 @@ import (
 )
 
 type Transcoder interface {
-	Transcode(ctx context.Context, profile Profile, in string) (io.ReadCloser, error)
+	Transcode(ctx context.Context, profile Profile, in string, out io.Writer) error
 }
 
 var UserProfiles = map[string]Profile{
@@ -106,24 +106,3 @@ func parseProfile(profile Profile, in string) (string, []string, error) {
 
 	return name, args, nil
 }
-
-// GuessExpectedSize guesses how big the transcoded file will be in bytes.
-// Handy if we want to send a Content-Length header to the client before
-// the transcode has finished. This way, clients like DSub can render their
-// scrub bar and duration as the track is streaming.
-//
-// The estimate should overshoot a bit (2s in this case) otherwise some HTTP
-// clients will shit their trousers given some unexpected bytes.
-func GuessExpectedSize(profile Profile, length time.Duration) int {
-	if length == 0 {
-		return 0
-	}
-
-	bytesPerSec := int(profile.BitRate() * 1000 / 8)
-
-	var guess int
-	guess += bytesPerSec * int(length.Seconds()-profile.seek.Seconds())
-	guess += bytesPerSec * 2 // 2s pading
-	guess += 10000           // 10kb byte padding
-	return guess
-}

transcode/transcode_test.go

@@ -1,47 +0,0 @@
-//go:build go1.18
-// +build go1.18
-
-package transcode_test
-
-import (
-	"context"
-	"io"
-	"testing"
-	"time"
-
-	"github.com/matryer/is"
-	"go.senan.xyz/gonic/transcode"
-)
-
-// FuzzGuessExpectedSize makes sure all of our profile's estimated transcode
-// file sizes are slightly bigger than the real thing.
-func FuzzGuessExpectedSize(f *testing.F) {
-	var profiles []transcode.Profile
-	for _, v := range transcode.UserProfiles {
-		profiles = append(profiles, v)
-	}
-
-	type track struct {
-		path   string
-		length time.Duration
-	}
-	var tracks []track
-	tracks = append(tracks, track{"testdata/5s.mp3", 5 * time.Second})
-	tracks = append(tracks, track{"testdata/10s.mp3", 10 * time.Second})
-
-	tr := transcode.NewFFmpegTranscoder()
-	f.Fuzz(func(t *testing.T, pseed uint8, tseed uint8) {
-		is := is.New(t)
-		profile := profiles[int(pseed)%len(profiles)]
-		track := tracks[int(tseed)%len(tracks)]
-
-		sizeGuess := transcode.GuessExpectedSize(profile, track.length)
-
-		reader, err := tr.Transcode(context.Background(), profile, track.path)
-		is.NoErr(err)
-
-		actual, err := io.ReadAll(reader)
-		is.NoErr(err)
-		is.True(sizeGuess > len(actual))
-	})
-}

transcode/transcoder_caching.go

@@ -7,8 +7,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-
-	"go.senan.xyz/gonic/iout"
 )
 
 const perm = 0644
@@ -24,14 +22,14 @@ func NewCachingTranscoder(t Transcoder, cachePath string) *CachingTranscoder {
 	return &CachingTranscoder{transcoder: t, cachePath: cachePath}
 }
 
-func (t *CachingTranscoder) Transcode(ctx context.Context, profile Profile, in string) (io.ReadCloser, error) {
+func (t *CachingTranscoder) Transcode(ctx context.Context, profile Profile, in string, out io.Writer) error {
 	if err := os.MkdirAll(t.cachePath, perm^0111); err != nil {
-		return nil, fmt.Errorf("make cache path: %w", err)
+		return fmt.Errorf("make cache path: %w", err)
 	}
 
 	name, args, err := parseProfile(profile, in)
 	if err != nil {
-		return nil, fmt.Errorf("split command: %w", err)
+		return fmt.Errorf("split command: %w", err)
 	}
 
 	key := cacheKey(name, args)
@@ -39,18 +37,21 @@ func (t *CachingTranscoder) Transcode(ctx context.Context, profile Profile, in s
 
 	cf, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE, 0644)
 	if err != nil {
-		return nil, fmt.Errorf("open cache file: %w", err)
+		return fmt.Errorf("open cache file: %w", err)
 	}
+	defer cf.Close()
+
 	if i, err := cf.Stat(); err == nil && i.Size() > 0 {
-		return cf, nil
+		_, _ = io.Copy(out, cf)
+		return nil
 	}
 
-	out, err := t.transcoder.Transcode(ctx, profile, in)
-	if err != nil {
-		return nil, fmt.Errorf("internal transcode: %w", err)
+	if err := t.transcoder.Transcode(ctx, profile, in, io.MultiWriter(out, cf)); err != nil {
+		os.Remove(path)
+		return fmt.Errorf("internal transcode: %w", err)
 	}
 
-	return iout.NewTeeCloser(out, cf), nil
+	return nil
 }
 
 func cacheKey(cmd string, args []string) string {

transcode/transcoder_ffmpeg.go

@@ -2,6 +2,7 @@ package transcode
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"os/exec"
@@ -17,23 +18,25 @@ func NewFFmpegTranscoder() *FFmpegTranscoder {
 
 var ErrFFmpegExit = fmt.Errorf("ffmpeg exited with non 0 status code")
 
-func (*FFmpegTranscoder) Transcode(ctx context.Context, profile Profile, in string) (io.ReadCloser, error) {
+func (*FFmpegTranscoder) Transcode(ctx context.Context, profile Profile, in string, out io.Writer) error {
 	name, args, err := parseProfile(profile, in)
 	if err != nil {
-		return nil, fmt.Errorf("split command: %w", err)
+		return fmt.Errorf("split command: %w", err)
 	}
 
-	preader, pwriter := io.Pipe()
-
 	cmd := exec.CommandContext(ctx, name, args...)
-	cmd.Stdout = pwriter
+	cmd.Stdout = out
+
 	if err := cmd.Start(); err != nil {
-		return nil, fmt.Errorf("starting cmd: %w", err)
+		return fmt.Errorf("starting cmd: %w", err)
 	}
 
-	go func() {
-		_ = pwriter.CloseWithError(cmd.Wait())
-	}()
-
-	return preader, nil
+	var exitErr *exec.ExitError
+	if err := cmd.Wait(); err != nil && !errors.As(err, &exitErr) {
+		return fmt.Errorf("waiting cmd: %w", err)
+	}
+	if code := cmd.ProcessState.ExitCode(); code > 1 {
+		return fmt.Errorf("%w: %d", ErrFFmpegExit, code)
+	}
+	return nil
 }

transcode/transcoder_none.go

@@ -2,6 +2,7 @@ package transcode
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"os"
 )
@@ -14,6 +15,14 @@ func NewNoneTranscoder() *NoneTranscoder {
 	return &NoneTranscoder{}
 }
 
-func (*NoneTranscoder) Transcode(ctx context.Context, _ Profile, in string) (io.ReadCloser, error) {
-	return os.Open(in)
+func (*NoneTranscoder) Transcode(ctx context.Context, _ Profile, in string, out io.Writer) error {
+	file, err := os.Open(in)
+	if err != nil {
+		return fmt.Errorf("open file: %w", err)
+	}
+	defer file.Close()
+	if _, err := io.Copy(out, file); err != nil {
+		return fmt.Errorf("copy file: %w", err)
+	}
+	return nil
 }