imageseq.go

//go:build amd64 || arm64

package ffmpeg

import (
	"fmt"

	"github.com/bstkhq/go-ffmpeg-ffi/avutil"
)

// ImageSequenceConfig configures image sequence reading or writing.
type ImageSequenceConfig struct {
	// Pattern is the file pattern with printf-style format specifier.
	// Examples: "frame_%04d.png", "image-%03d.jpg", "out%d.bmp"
	Pattern string

	// StartNumber is the first frame number (default: 0).
	StartNumber int

	// FrameRate is the frame rate for the sequence.
	// For decoding, this determines the duration of each frame.
	// For encoding, this is the output frame rate.
	FrameRate avutil.Rational
}

// NewImageSequenceDecoder creates a decoder that reads an image sequence as video.
// The pattern should use printf-style format specifier (e.g., "frame_%04d.png").
// The sequence is decoded as a video stream with the specified frame rate.
func NewImageSequenceDecoder(config ImageSequenceConfig, decoderOpts *DecoderOptions) (*Decoder, error) {
	if config.Pattern == "" {
		return nil, fmt.Errorf("ffmpeg: image sequence pattern cannot be empty")
	}
	return NewDecoder(config.Pattern, imageSequenceDecoderOptions(config, decoderOpts))
}

func imageSequenceDecoderOptions(config ImageSequenceConfig, decoderOpts *DecoderOptions) *DecoderOptions {
	decoderOpts = cloneDecoderOptions(decoderOpts)
	if decoderOpts.AVOptions == nil {
		decoderOpts.AVOptions = make(map[string]string)
	}
	decoderOpts.Format = "image2"
	decoderOpts.AVOptions["pattern_type"] = "sequence"

	if config.StartNumber > 0 {
		decoderOpts.AVOptions["start_number"] = fmt.Sprintf("%d", config.StartNumber)
	}

	if config.FrameRate.Num > 0 && config.FrameRate.Den > 0 {
		decoderOpts.AVOptions["framerate"] = fmt.Sprintf("%d/%d", config.FrameRate.Num, config.FrameRate.Den)
	}

	return decoderOpts
}

// NewImageSequenceEncoder creates an encoder that writes video as an image sequence.
// The pattern should use printf-style format specifier (e.g., "frame_%04d.png").
// The output format is determined by the file extension in the pattern.
func NewImageSequenceEncoder(config ImageSequenceConfig, width, height int, pixFmt PixelFormat) (*Encoder, error) {
	if config.Pattern == "" {
		return nil, fmt.Errorf("ffmpeg: image sequence pattern cannot be empty")
	}

	// Determine codec from pattern extension
	codec := "png" // default
	if len(config.Pattern) > 4 {
		ext := config.Pattern[len(config.Pattern)-4:]
		switch ext {
		case ".jpg", ".JPG":
			codec = "mjpeg"
		case "jpeg", "JPEG":
			codec = "mjpeg"
		case ".bmp", ".BMP":
			codec = "bmp"
		case ".png", ".PNG":
			codec = "png"
		}
	}

	frameRate := config.FrameRate
	if frameRate.Num <= 0 || frameRate.Den <= 0 {
		frameRate = NewRational(25, 1)
	}

	// Map codec name to codec ID
	var codecID CodecID
	switch codec {
	case "mjpeg":
		codecID = CodecIDMJPEG
	case "bmp":
		codecID = CodecIDBMP
	case "png":
		codecID = CodecIDPNG
	default:
		codecID = CodecIDPNG
	}

	return NewEncoder(config.Pattern, &EncoderOptions{
		Video: &VideoEncoderConfig{
			Width:       width,
			Height:      height,
			PixelFormat: pixFmt,
			FrameRate:   frameRate,
			Codec:       codecID,
		},
	})
}