2b0a0dbcf5
...instead of creating a new string with `fmt.Sprintf` and writing it with to the file separately.
127 lines
3.1 KiB
Go
127 lines
3.1 KiB
Go
package main
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import (
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"archive/zip"
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"bytes"
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"fmt"
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"io"
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"os"
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"os/exec"
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"path/filepath"
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"strings"
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)
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// Create a file describing frames and their durations for FFmpeg's concat demuxer
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// https://ffmpeg.org/ffmpeg-formats.html#concat
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func makeConcatDemuxFile(manifest UgoiraManifest, frameDescFile *os.File) {
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frames := manifest.Body.Frames
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for _, frame := range frames {
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frameDur := float32(frame.Delay) / 1000 // convert to seconds
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fmt.Fprintf(frameDescFile, "file '%s'\n", frame.File)
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fmt.Fprintf(frameDescFile, "duration %f\n", frameDur)
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}
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// repeat last frame (see: https://trac.ffmpeg.org/wiki/Slideshow#Concatdemuxer
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lastFrame := frames[len(frames)-1]
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fmt.Fprintf(frameDescFile, "file '%s'\n", lastFrame.File)
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}
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func callFFmpeg(frameDescPath, outputFilePath, workDir, ffmpegArgs string) error {
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const ffmpegBaseArgs = `-hide_banner
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-loglevel warning
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-f concat -i %s
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-fps_mode vfr`
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// Default codec arguments, for a VP9 WebM
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const ffmpegDefaultArgs = `-an
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-q:v 10
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-c:v libvpx-vp9
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-b:v 1M
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-crf 5 %s`
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var ffmpegArgsTemp string
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if len(ffmpegArgs) > 0 {
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ffmpegArgsTemp = ffmpegBaseArgs + " " + ffmpegArgs
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} else {
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ffmpegArgsTemp = ffmpegBaseArgs + " " + ffmpegDefaultArgs
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}
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cmdArgs := fmt.Sprintf(ffmpegArgsTemp, frameDescPath, outputFilePath)
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cmdArgsSplit := strings.Fields(cmdArgs)
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ffmpegProc := exec.Command("ffmpeg", cmdArgsSplit...)
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var stderr bytes.Buffer
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ffmpegProc.Stderr = &stderr
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ffmpegProc.Dir = workDir
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if err := ffmpegProc.Run(); err != nil {
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fmt.Fprintf(os.Stderr, "FFmpeg stderr:\n%s\n", stderr.String())
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if exitErr, ok := err.(*exec.ExitError); ok {
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return fmt.Errorf("ffmpeg exited with non zero code: %d", exitErr.ExitCode())
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}
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return fmt.Errorf("Could not run ffmpeg: %w", err)
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}
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return nil
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}
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// Reads and uncompress a frame from the archive and saves it
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func uncompressFrame(file *zip.File, framePath string) error {
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fileFp, err := file.Open()
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if err != nil {
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return err
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}
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defer fileFp.Close()
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outFp, err := os.Create(framePath)
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if err != nil {
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return err
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}
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defer outFp.Close()
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if _, err := io.Copy(outFp, fileFp); err != nil {
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return err
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}
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return nil
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}
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func unpackUgoira(ugoiraPath, outDir string) error {
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reader, err := zip.OpenReader(ugoiraPath)
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if err != nil {
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return err
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}
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defer reader.Close()
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for _, file := range reader.File {
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path := filepath.Join(outDir, file.Name)
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if err := uncompressFrame(file, path); err != nil {
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return err
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}
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}
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return nil
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}
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func ugoira2video(manifest UgoiraManifest, ugoiraFileName, vidOut, ffmpegArgs string) error {
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tdir, err := os.MkdirTemp("", "u2vwd-")
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if err != nil {
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return err
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}
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defer os.RemoveAll(tdir)
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fraFp, err := os.CreateTemp(tdir, "frames*.txt")
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if err != nil {
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return err
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}
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defer os.Remove(fraFp.Name())
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defer fraFp.Close()
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vidOutAbs, err := filepath.Abs(vidOut)
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if err != nil {
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return err
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}
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if err := unpackUgoira(ugoiraFileName, tdir); err != nil {
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return fmt.Errorf("Could not unpack Ugoira: %w", err)
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}
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makeConcatDemuxFile(manifest, fraFp)
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if err := callFFmpeg(fraFp.Name(), vidOutAbs, tdir, ffmpegArgs); err != nil {
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return err
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}
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return nil
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}
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