Google Cloud Speech API 调用注意事项及调用方式__.Net版2

来源：互联网发布：2017大数据概念股龙头编辑：程序博客网时间：2024/05/18 03:12

在上一章已详细说明如何读取本地音频文件，调用GoogleCloudSpeech API转换为文字。从中可以看出，对音频文件的播放长度严格地限制在60s以内。对此限制，Google采用将音频文件上传到Cloud Storage的Bucket中，然后进行文字转换，大大地增长了文件的播放长度。针对在Google Cloud PlatForm中的系列操作及上传文件到Cloud Storage Bucket中的方式，请查看GoogleCloudSpeechAPI 的调用注意事项。

读取Cloud Storage Bucket中的音频文件进行文字转换

注：如下Demo是windows应用程序，所有方法都为static

1.创建类型为CloudSpeechAPIService的方法，目的是通过环境变量获取Google的凭证，连接在云平台建立的项目。PS：如果此方法出现异常，请查看上一章的前提条件二。

static public CloudSpeechAPIService CreateAuthorizedClient()    {        GoogleCredential credential =GoogleCredential.GetApplicationDefaultAsync().Result;//读取环境变量中的GOOGLE_APPLICATION_CREDENTIALS        if (credential.IsCreateScopedRequired)        {            credential = credential.CreateScoped(new[]            {                CloudSpeechAPIService.Scope.CloudPlatform            });//获取认证        }        return new CloudSpeechAPIService(new BaseClientService.Initializer()        {            HttpClientInitializer = credential,            ApplicationName = "DotNet Google Cloud Platform Speech Sample",        });    }

2.选择Cloud Storage Bucket中的音频文件，调用该API进行文字转换。ps：音频文件格式最好为1声道PCM，播放时间小于80minutes否则转换容易出错。

   private static void SpeechTotextByUri()        {            var service = CreateAuthorizedClient();//获取Google云认证            var request = new Google.Apis.CloudSpeechAPI.v1beta1.Data.AsyncRecognizeRequest()            {                Config = new Google.Apis.CloudSpeechAPI.v1beta1.Data.RecognitionConfig()                {                    Encoding = "LINEAR16",//编码格式PCM                    SampleRate = 16000,//采样频率16000HZ                    LanguageCode = "en-US"//英文播放文件                    //  LanguageCode = "cmn-Hans-CN"中文播放文件                },                Audio = new Google.Apis.CloudSpeechAPI.v1beta1.Data.RecognitionAudio()                {                     Uri= "gs://Storage中的Bucket名称/该Bucket中的音频文件"//如Google提供的 Uri= "gs://cloud-samples-tests/speech/brooklyn.flac"                }            };            DateTime startTime = DateTime.Now;            Console.WriteLine("Sarte Time ：" + startTime);            StringBuilder sb = new StringBuilder();            try            {                var asyncResponse = service.Speech.Asyncrecognize(request).Execute();                var name = asyncResponse.Name;                Google.Apis.CloudSpeechAPI.v1beta1.Data.Operation op;                do                {                    Console.WriteLine("Waiting for server processing...");                    Thread.Sleep(1000);                    op = service.Operations.Get(name).Execute();                    if (op.Error?.Message != null)                    {                        Console.WriteLine(op.Error.Message);                    }                } while (!(op.Done.HasValue && op.Done.Value));                dynamic results = op.Response["results"];                StringBuilder sbContent = new StringBuilder();                foreach (var result in results)                {                    foreach (var alternative in result.alternatives)                    {                        sbContent.Append(alternative.transcript);                    }                }                sb.Append(sbContent);                Console.WriteLine("The result:");                Console.WriteLine();                Console.WriteLine(sbContent.ToString());                Console.WriteLine();            }            catch (Exception ex)            {                Console.WriteLine(ex.Message);            }            DateTime endTime = DateTime.Now;            var timeTaken = endTime - startTime;            Console.WriteLine("End Time:" + endTime + "\t" + "Time-taken:" + (timeTaken));            sb.Append("\r\nEnd Time:" + endTime + "\t" + "Time-taken:" + (timeTaken));            try            {              //将转换的文字内容保存到本地                StreamWriter sw = new StreamWriter(Directory.GetCurrentDirectory() + $"\\{filename}_result.txt");                sw.Write(sb.ToString());                sw.Close();            }            catch (Exception ex)            {                Console.WriteLine("Write file failed!\t" + ex.Message);            }            Console.WriteLine();            Console.WriteLine("Enter any key to exit the program!");            Console.ReadKey();        }

PS：使用的命名空间有：

using System;using Google.Apis.CloudSpeechAPI.v1beta1;using Google.Apis.Auth.OAuth2;using Google.Apis.Services;using System.IO;using System.Text;using System.Threading;using Google.Cloud.Storage.V1;

结果如下：
这里写图片描述

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