fix: openai 音频模型流模式未正确计费 (#2160)

relay/channel/openai/relay-openai.go

@@ -122,6 +122,10 @@ func OaiStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Re
 	var usage = &dto.Usage{}
 	var streamItems []string // store stream items
 	var lastStreamData string
+	var secondLastStreamData string // 存储倒数第二个stream data，用于音频模型
+
+	// 检查是否为音频模型
+	isAudioModel := strings.Contains(strings.ToLower(model), "audio")
 
 	helper.StreamScannerHandler(c, resp, info, func(data string) bool {
 		if lastStreamData != "" {
@@ -131,12 +135,35 @@ func OaiStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Re
 			}
 		}
 		if len(data) > 0 {
+			// 对音频模型，保存倒数第二个stream data
+			if isAudioModel && lastStreamData != "" {
+				secondLastStreamData = lastStreamData
+			}
+
 			lastStreamData = data
 			streamItems = append(streamItems, data)
 		}
 		return true
 	})
 
+	// 对音频模型，从倒数第二个stream data中提取usage信息
+	if isAudioModel && secondLastStreamData != "" {
+		var streamResp struct {
+			Usage *dto.Usage `json:"usage"`
+		}
+		err := json.Unmarshal([]byte(secondLastStreamData), &streamResp)
+		if err == nil && streamResp.Usage != nil && service.ValidUsage(streamResp.Usage) {
+			usage = streamResp.Usage
+			containStreamUsage = true
+
+			if common.DebugEnabled {
+				logger.LogDebug(c, fmt.Sprintf("Audio model usage extracted from second last SSE: PromptTokens=%d, CompletionTokens=%d, TotalTokens=%d, InputTokens=%d, OutputTokens=%d",
+					usage.PromptTokens, usage.CompletionTokens, usage.TotalTokens,
+					usage.InputTokens, usage.OutputTokens))
+			}
+		}
+	}
+
 	// 处理最后的响应
 	shouldSendLastResp := true
 	if err := handleLastResponse(lastStreamData, &responseId, &createAt, &systemFingerprint, &model, &usage,