Flamenco/internal/worker/command_ffmpeg.go

package worker

// SPDX-License-Identifier: GPL-3.0-or-later

/* This file contains the commands in the "ffmpeg" type group. */

import (
	"bufio"
	"context"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"

	"github.com/google/shlex"
	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"

	"git.blender.org/flamenco/pkg/api"
	"git.blender.org/flamenco/pkg/crosspath"
)

type CreateVideoParams struct {
	exe        string   // Expansion of `{ffmpeg}`: executable path + its CLI parameters defined by the Manager.
	fps        float64  // Frames per second of the video file.
	inputGlob  string   // Glob of input files.
	outputFile string   // File to save the video to.
	argsBefore []string // Additional CLI arguments from `exe`.
	args       []string // Additional CLI arguments defined by the job compiler script, to between the input and output filenames.
}

// cmdFramesToVideo uses ffmpeg to concatenate image frames to a video file.
func (ce *CommandExecutor) cmdFramesToVideo(ctx context.Context, logger zerolog.Logger, taskID string, cmd api.Command) error {
	cmdCtx, cmdCtxCancel := context.WithCancel(ctx)
	defer cmdCtxCancel()

	execCmd, cleanup, err := ce.cmdFramesToVideoExeCommand(cmdCtx, logger, taskID, cmd)
	if err != nil {
		return err
	}
	defer cleanup()

	outPipe, err := execCmd.StdoutPipe()
	if err != nil {
		return err
	}
	execCmd.Stderr = execCmd.Stdout // Redirect stderr to stdout.

	if err := execCmd.Start(); err != nil {
		logger.Error().Err(err).Msg("error starting CLI execution")
		return err
	}

	ffmpegPID := execCmd.Process.Pid
	logger = logger.With().Int("pid", ffmpegPID).Logger()

	reader := bufio.NewReaderSize(outPipe, StdoutBufferSize)
	logChunker := NewLogChunker(taskID, ce.listener, ce.timeService)

	for {
		lineBytes, isPrefix, readErr := reader.ReadLine()
		if readErr == io.EOF {
			break
		}
		if readErr != nil {
			logger.Error().Err(err).Msg("error reading stdout/err")
			return err
		}
		line := string(lineBytes)
		if isPrefix {
			logger.Warn().
				Str("line", fmt.Sprintf("%s...", line[:256])).
				Int("lineLength", len(line)).
				Msg("unexpectedly long line read, truncating")
		}

		logger.Debug().Msg(line)
		if err := logChunker.Append(ctx, fmt.Sprintf("pid=%d > %s", ffmpegPID, line)); err != nil {
			return fmt.Errorf("appending log entry to log chunker: %w", err)
		}
	}
	if err := logChunker.Flush(ctx); err != nil {
		return fmt.Errorf("flushing log chunker: %w", err)
	}

	if err := execCmd.Wait(); err != nil {
		logger.Error().Err(err).Msg("error in CLI execution")
		return err
	}

	if execCmd.ProcessState.Success() {
		logger.Info().Msg("command exited succesfully")
	} else {
		logger.Error().
			Int("exitCode", execCmd.ProcessState.ExitCode()).
			Msg("command exited abnormally")
		return fmt.Errorf("command exited abnormally with code %d", execCmd.ProcessState.ExitCode())
	}

	return nil
}

func (ce *CommandExecutor) cmdFramesToVideoExeCommand(
	ctx context.Context,
	logger zerolog.Logger,
	taskID string,
	cmd api.Command,
) (*exec.Cmd, func(), error) {
	parameters, err := cmdFramesToVideoParams(logger, cmd)
	if err != nil {
		return nil, nil, err
	}

	inputGlobArgs, cleanup, err := parameters.getInputGlob()

	// runCleanup should be used if the cleanup function is *not* going to be
	// returned (i.e. in case of error).
	runCleanup := func() {
		if cleanup != nil {
			cleanup()
		}
	}

	if err != nil {
		runCleanup()
		return nil, nil, fmt.Errorf("creating input for FFmpeg: %w", err)
	}

	cliArgs := make([]string, 0)
	cliArgs = append(cliArgs, parameters.argsBefore...)
	cliArgs = append(cliArgs, inputGlobArgs...)
	cliArgs = append(cliArgs, parameters.args...)
	cliArgs = append(cliArgs, parameters.outputFile)

	execCmd := ce.cli.CommandContext(ctx, parameters.exe, cliArgs...)
	if execCmd == nil {
		runCleanup()
		logger.Error().Msg("unable to create command executor")
		return nil, nil, ErrNoExecCmd
	}
	logger.Info().
		Str("execCmd", execCmd.String()).
		Msg("going to execute FFmpeg")

	if err := ce.listener.LogProduced(ctx, taskID, fmt.Sprintf("going to run: %s %q", parameters.exe, cliArgs)); err != nil {
		runCleanup()
		return nil, nil, err
	}

	return execCmd, cleanup, nil
}

func cmdFramesToVideoParams(logger zerolog.Logger, cmd api.Command) (CreateVideoParams, error) {
	var (
		parameters CreateVideoParams
		ok         bool
	)

	if parameters.exe, ok = cmdParameter[string](cmd, "exe"); !ok || parameters.exe == "" {
		logger.Warn().Interface("command", cmd).Msg("missing 'exe' parameter")
		return parameters, NewParameterMissingError("exe", cmd)
	}
	if parameters.fps, ok = cmdParameter[float64](cmd, "fps"); !ok || parameters.fps == 0.0 {
		logger.Warn().Interface("command", cmd).Msg("missing 'fps' parameter")
		return parameters, NewParameterMissingError("fps", cmd)
	}
	if parameters.inputGlob, ok = cmdParameter[string](cmd, "inputGlob"); !ok || parameters.inputGlob == "" {
		logger.Warn().Interface("command", cmd).Msg("missing 'inputGlob' parameter")
		return parameters, NewParameterMissingError("inputGlob", cmd)
	}
	if parameters.outputFile, ok = cmdParameter[string](cmd, "outputFile"); !ok || parameters.outputFile == "" {
		logger.Warn().Interface("command", cmd).Msg("missing 'outputFile' parameter")
		return parameters, NewParameterMissingError("outputFile", cmd)
	}
	if parameters.argsBefore, ok = cmdParameterAsStrings(cmd, "argsBefore"); !ok {
		logger.Warn().Interface("command", cmd).Msg("invalid 'argsBefore' parameter")
		return parameters, NewParameterInvalidError("argsBefore", cmd, "cannot convert to list of strings")
	}
	if parameters.args, ok = cmdParameterAsStrings(cmd, "args"); !ok {
		logger.Warn().Interface("command", cmd).Msg("invalid 'args' parameter")
		return parameters, NewParameterInvalidError("args", cmd, "cannot convert to list of strings")
	}

	// Move any CLI args from 'exe' to 'argsBefore'.
	exeArgs, err := shlex.Split(parameters.exe)
	if err != nil {
		logger.Warn().Err(err).Interface("command", cmd).Msg("error parsing 'exe' parameter with shlex")
		return parameters, NewParameterInvalidError("exe", cmd, err.Error())
	}
	if len(exeArgs) > 1 {
		allArgsBefore := []string{}
		allArgsBefore = append(allArgsBefore, exeArgs[1:]...)
		allArgsBefore = append(allArgsBefore, parameters.argsBefore...)
		parameters.exe = exeArgs[0]
		parameters.argsBefore = allArgsBefore
	}
	parameters.args = append(parameters.args,
		"-r", strconv.FormatFloat(parameters.fps, 'f', -1, 64))

	return parameters, nil
}

// getInputGlob constructs CLI arguments for FFmpeg input file globbing.
// The 2nd return value is a cleanup function.
func (p *CreateVideoParams) getInputGlob() ([]string, func(), error) {
	if runtime.GOOS == "windows" {
		return createIndexFile(p.inputGlob, p.fps)
	}

	cliArgs := []string{
		"-pattern_type", "glob",
		"-i", crosspath.ToSlash(p.inputGlob),
	}
	cleanup := func() {}
	return cliArgs, cleanup, nil
}

// createIndexFile creates an FFmpeg index file, to make up for FFmpeg's lack of globbing support on Windows.
func createIndexFile(inputGlob string, frameRate float64) ([]string, func(), error) {
	globDir := filepath.Dir(inputGlob)

	files, err := filepath.Glob(inputGlob)
	if err != nil {
		return nil, nil, err
	}
	if len(files) == 0 {
		return nil, nil, fmt.Errorf("no files found at %s", inputGlob)
	}

	indexFilename := filepath.Join(globDir, "ffmpeg-file-index.txt")
	indexFile, err := os.Create(indexFilename)
	if err != nil {
		return nil, nil, err
	}
	defer indexFile.Close()

	frameDuration := 1.0 / frameRate
	for _, fname := range files {
		escaped := strings.ReplaceAll(fname, "'", "\\'")
		fmt.Fprintf(indexFile, "file '%s'\n", escaped)
		fmt.Fprintf(indexFile, "duration %f\n", frameDuration)
	}

	cliArgs := []string{
		"-f", "concat",
		"-safe", "0", // To allow absolute paths in the index file.
		"-i", indexFilename,
	}

	cleanup := func() {
		err := os.Remove(indexFilename)
		if err != nil && !errors.Is(err, fs.ErrNotExist) {
			log.Warn().
				Err(err).
				Str("filename", indexFilename).
				Msg("error removing temporary FFmpeg index file")
		}
	}

	return cliArgs, cleanup, nil
}