nsfwapp/backend/analyze_videomae.go

package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"math"
	"net/http"
	"os"
	"strings"
	"time"
)

const (
	analyzeVideoMAEClipWindowSeconds = 4.0
	analyzeVideoMAEClipStrideSeconds = 2.0
	analyzeVideoMAEMinScore          = 0.34
	analyzeVideoMAERequestBatchSize  = 8
	analyzeVideoMAEMaxClips          = 96
	analyzeVideoMAERequestTimeout    = 45 * time.Second
	analyzeVideoMAETotalTimeout      = 2 * time.Minute
)

type analyzeVideoMAEClipReqItem struct {
	Time  float64  `json:"time"`
	Start float64  `json:"start"`
	End   float64  `json:"end"`
	Paths []string `json:"paths"`
}

type analyzeVideoMAEClipPredictReq struct {
	Clips     []analyzeVideoMAEClipReqItem `json:"clips"`
	NumFrames int                          `json:"numFrames,omitempty"`
}

type analyzeVideoMAEClipPrediction struct {
	Time             float64               `json:"time"`
	Start            float64               `json:"start"`
	End              float64               `json:"end"`
	SexPosition      string                `json:"sexPosition"`
	SexPositionScore float64               `json:"sexPositionScore"`
	Source           string                `json:"source,omitempty"`
	Scores           []TrainingScoredLabel `json:"scores,omitempty"`
}

type analyzeVideoMAEClipPredictResp struct {
	OK          bool                            `json:"ok"`
	Available   bool                            `json:"available"`
	Predictions []analyzeVideoMAEClipPrediction `json:"predictions"`
	Error       string                          `json:"error,omitempty"`
}

func analyzeVideoMAEEnabled() bool {
	raw := strings.ToLower(strings.TrimSpace(os.Getenv("VIDEOMAE_ANALYZE_ENABLED")))
	return raw == "" || raw == "1" || raw == "true" || raw == "yes" || raw == "on"
}

func buildAnalyzeVideoMAEClips(
	samples []videoFrameSample,
	duration float64,
) []analyzeVideoMAEClipReqItem {
	if len(samples) == 0 || duration <= 0 {
		return []analyzeVideoMAEClipReqItem{}
	}

	clips := []analyzeVideoMAEClipReqItem{}
	halfWindow := analyzeVideoMAEClipWindowSeconds / 2
	if halfWindow <= 0 {
		halfWindow = 2
	}

	lastCenter := -math.MaxFloat64
	for _, sample := range samples {
		center := math.Max(0, sample.Time)
		if len(clips) > 0 && center-lastCenter < analyzeVideoMAEClipStrideSeconds-0.001 {
			continue
		}

		start := math.Max(0, center-halfWindow)
		end := center + halfWindow
		if duration > 0 {
			end = math.Min(duration, end)
		}
		if end <= start {
			end = math.Min(duration, start+math.Max(1, float64(analyzeVideoFrameIntervalSeconds)))
		}

		paths := []string{}
		for _, candidate := range samples {
			if candidate.Time < start-0.001 || candidate.Time > end+0.001 {
				continue
			}

			path := strings.TrimSpace(candidate.Path)
			if path != "" {
				paths = append(paths, path)
			}
		}

		if len(paths) == 0 {
			continue
		}

		clips = append(clips, analyzeVideoMAEClipReqItem{
			Time:  center,
			Start: start,
			End:   end,
			Paths: paths,
		})
		lastCenter = center
	}

	return clips
}

func limitAnalyzeVideoMAEClips(clips []analyzeVideoMAEClipReqItem, maxClips int) []analyzeVideoMAEClipReqItem {
	if maxClips <= 0 || len(clips) <= maxClips {
		return clips
	}
	if maxClips == 1 {
		return clips[:1]
	}

	out := make([]analyzeVideoMAEClipReqItem, 0, maxClips)
	lastIdx := -1
	for i := 0; i < maxClips; i++ {
		idx := int(math.Round(float64(i) * float64(len(clips)-1) / float64(maxClips-1)))
		if idx <= lastIdx {
			idx = lastIdx + 1
		}
		if idx >= len(clips) {
			idx = len(clips) - 1
		}
		out = append(out, clips[idx])
		lastIdx = idx
	}

	return out
}

func predictVideoMAEPositionClipsForAnalyze(
	ctx context.Context,
	clips []analyzeVideoMAEClipReqItem,
	onProgress func(current int, total int),
) ([]analyzeVideoMAEClipPrediction, error) {
	if len(clips) == 0 {
		return []analyzeVideoMAEClipPrediction{}, nil
	}

	if !trainingRecognitionEnabled() {
		if onProgress != nil {
			onProgress(len(clips), len(clips))
		}
		return []analyzeVideoMAEClipPrediction{}, nil
	}

	out := []analyzeVideoMAEClipPrediction{}
	for start := 0; start < len(clips); start += analyzeVideoMAERequestBatchSize {
		end := start + analyzeVideoMAERequestBatchSize
		if end > len(clips) {
			end = len(clips)
		}

		payload := analyzeVideoMAEClipPredictReq{
			Clips:     clips[start:end],
			NumFrames: trainingVideoMAENumFrames,
		}

		body, err := json.Marshal(payload)
		if err != nil {
			return out, err
		}

		parsed, err := func() (analyzeVideoMAEClipPredictResp, error) {
			var parsed analyzeVideoMAEClipPredictResp

			reqCtx, cancel := context.WithTimeout(ctx, analyzeVideoMAERequestTimeout)
			defer cancel()

			req, err := http.NewRequestWithContext(
				reqCtx,
				http.MethodPost,
				analyzeAIServerURL()+"/predict-position-clips",
				bytes.NewReader(body),
			)
			if err != nil {
				return parsed, err
			}

			req.Header.Set("Content-Type", "application/json")
			addAIServerAuth(req)

			client := &http.Client{
				Timeout: analyzeVideoMAERequestTimeout + 5*time.Second,
			}

			res, err := client.Do(req)
			if err != nil {
				if ctxErr := ctx.Err(); ctxErr != nil {
					return parsed, ctxErr
				}
				return parsed, err
			}

			rawBody, readErr := io.ReadAll(res.Body)
			statusCode := res.StatusCode
			_ = res.Body.Close()
			if readErr != nil {
				if ctxErr := ctx.Err(); ctxErr != nil {
					return parsed, ctxErr
				}
				return parsed, readErr
			}

			if err := json.Unmarshal(rawBody, &parsed); err != nil {
				if ctxErr := ctx.Err(); ctxErr != nil {
					return parsed, ctxErr
				}
				return parsed, fmt.Errorf("AI server VideoMAE JSON ungueltig: HTTP %d: %s", statusCode, strings.TrimSpace(string(rawBody)))
			}

			if statusCode < 200 || statusCode >= 300 || !parsed.OK {
				msg := strings.TrimSpace(parsed.Error)
				if msg == "" {
					msg = fmt.Sprintf("AI server VideoMAE HTTP %d", statusCode)
				}
				return parsed, fmt.Errorf("%s", msg)
			}

			return parsed, nil
		}()
		if err != nil {
			return out, err
		}

		if !parsed.Available {
			if onProgress != nil {
				onProgress(len(clips), len(clips))
			}
			return out, nil
		}

		out = append(out, parsed.Predictions...)
		if onProgress != nil {
			onProgress(end, len(clips))
		}
	}

	return out, nil
}

func applyVideoMAEPositionClipsForAnalyze(
	ctx context.Context,
	file string,
	samples []videoFrameSample,
	duration float64,
	highlightHits []analyzeHit,
	positionEvidence []analyzePositionEvidence,
	onProgress func(current int, total int),
) ([]analyzeHit, []analyzePositionEvidence) {
	if !analyzeVideoMAEEnabled() {
		return highlightHits, positionEvidence
	}

	clips := buildAnalyzeVideoMAEClips(samples, duration)
	if len(clips) == 0 {
		return highlightHits, positionEvidence
	}
	if len(clips) > analyzeVideoMAEMaxClips {
		appLogf(
			"VideoMAE Clip-Analyse begrenzt file=%q clips=%d max=%d",
			strings.TrimSpace(file),
			len(clips),
			analyzeVideoMAEMaxClips,
		)
		clips = limitAnalyzeVideoMAEClips(clips, analyzeVideoMAEMaxClips)
	}

	if onProgress != nil {
		onProgress(0, len(clips))
	}

	videoCtx, cancel := context.WithTimeout(ctx, analyzeVideoMAETotalTimeout)
	defer cancel()

	predictions, err := predictVideoMAEPositionClipsForAnalyze(videoCtx, clips, onProgress)
	if err != nil {
		if ctx.Err() == nil {
			appLogf(
				"VideoMAE Clip-Analyse begrenzt/übersprungen file=%q predictions=%d err=%v",
				strings.TrimSpace(file),
				len(predictions),
				err,
			)
			if onProgress != nil {
				onProgress(len(clips), len(clips))
			}
			appLogln("VideoMAE Clip-Analyse übersprungen:", err)
		}
	}

	for _, pred := range predictions {
		label := strings.ToLower(strings.TrimSpace(pred.SexPosition))
		if !isAnalyzeTimelinePositionLabel(label) {
			continue
		}

		score := clamp01(pred.SexPositionScore)
		if score < analyzeVideoMAEMinScore {
			continue
		}

		start := math.Max(0, pred.Start)
		end := pred.End
		if duration > 0 {
			end = math.Min(duration, end)
		}
		if end <= start {
			end = math.Min(duration, start+math.Max(1, float64(analyzeVideoFrameIntervalSeconds)))
		}

		source := strings.ToLower(strings.TrimSpace(pred.Source))
		if source == "" {
			source = "videomae"
		}

		positionEvidence = append(positionEvidence, analyzePositionEvidence{
			Time:    pred.Time,
			Start:   start,
			End:     end,
			Label:   label,
			Score:   score,
			Source:  source,
			HasClip: true,
		})
	}

	return highlightHits, positionEvidence
}