feat(ai): account for num_inference_steps inT2I latency inference sco…

…re calculation (#3074)

* fix(ai): Fix accuracy of T2I latency score when num_inference_steps provided

* refactor(ai): update numInferenceSteps default

This commit ensures that the same numInferenceSteps default value is
used as the one set in
https://github.com/livepeer/ai-worker/blob/31fe460a45e1d9e908d3a1bdcfdd8822c3889214/runner/app/routes/text_to_image.py#L28.

---------

Co-authored-by: Elite Encoder <john@eliteencoder.net>

server/ai_process.go

@@ -110,12 +110,18 @@ func submitTextToImage(ctx context.Context, params aiRequestParams, sess *AISess
 		balUpdate.Status = ReceivedChange
 	}
 
-	// TODO: Refine this rough estimate in future iterations
-	numImages := 1
+	// TODO: Refine this rough estimate in future iterations.
+	// TODO: Default values for the number of images and inference steps are currently hardcoded.
+	// These should be managed by the nethttpmiddleware. Refer to issue LIV-412 for more details.
+	numImages := float64(1)
 	if req.NumImagesPerPrompt != nil {
-		numImages = *req.NumImagesPerPrompt
+		numImages = float64(*req.NumImagesPerPrompt)
+	}
+	numInferenceSteps := float64(50)
+	if req.NumInferenceSteps != nil {
+		numInferenceSteps = float64(*req.NumInferenceSteps)
 	}
-	sess.LatencyScore = took.Seconds() / float64(outPixels) / float64(numImages)
+	sess.LatencyScore = took.Seconds() / float64(outPixels) / (numImages * numInferenceSteps)
 
 	return resp.JSON200, nil
 }