音频视频的播放的进度调整(以.net为例)

Background：对于音视频在线播放，一些小应用是靠nginx处理访问视频、音频文件的请求，对外应用的一般会托管至各种云上使用相关的服务。前者存在巨大的安全隐患，后者会有一定的成本。有的时候还是需要自己造个轮子。

step 1：先实现文件下载

[HttpGet]
public IActionResult Get()
{
    var filePath = @"E:\test.wav";
    var name = @"tes1t.wav";
    FileStream fs = new FileStream(filePath, FileMode.Open);
    return  File(fs, "application/octet-stream", name);
}

前面的audio标签是可以播放和正常下载的，但是并不能实现进度控件的调整

step2：请求的区别

Nginx的处理是可以实现播放进度调整的。在前端请求相同的情况下，两者用nginx代理和刚才的下载的主要区别如下：

可以看出Content-Range对应的正是请求头中的Range

关于这几个头部信息可参考这篇文章：https://blog.csdn.net/thewindkee/article/details/80189434

这3个标签同时也是文件实现断点续传的关键。

step3：断点续传

这样进度的调整就转化为了断点续传功能。

.net可参考：https://www.cnblogs.com/Leo_wl/p/8467796.html

  public FileStreamResult Index(string auth,string filename)
         {
             if (auth != null && auth.Length >)
             {
                  // 处理权限问题
             }
             else
             {
                 return null;
             }

             int size, end, length = ;
             int start;

             MemoryStream Mstream;
             using (FileStream reader = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read))
             {
                 byte[] bytes = new byte[reader.Length];
                 //var strd = new StreamReader(reader);

                 size = bytes.Length;
                 start = ;
                 end = size - ;
                 length = size;
                 Response.Headers["Accept-Ranges"] = "0-" + size;
                 if (!String.IsNullOrEmpty(Request.Headers["Range"]))
                 {
                     int anotherStart = start;
                     int anotherEnd = end;
                     var headerRange = Request.Headers["Range"];
                     string[] arr_split = headerRange.FirstOrDefault().Split(new char[] { Convert.ToChar("=") });
                     Debug.WriteLine(arr_split);
                     string range = arr_split[];
                     if (range.IndexOf(",") > -)
                     {
                         Response.Headers["Content-Range"] = "bytes " + start + "-" + end + "/" + size;

                         Response.StatusCode = ;

                     }
                     if (range.StartsWith("-"))
                     {
                         // The n-number of the last bytes is requested
                         anotherStart = size - Convert.ToInt32(range.Substring());
                     }
                     else
                     {
                         arr_split = range.Split(new char[] { Convert.ToChar("-") });
                         anotherStart = Convert.ToInt32(arr_split[]);
                         int temp = ;
                         anotherEnd = (arr_split.Length >  && Int32.TryParse(arr_split[].ToString(), out temp)) ? Convert.ToInt32(arr_split[]) : size;
                     }
                     anotherEnd = (anotherEnd > end) ? end : anotherEnd;
                     if (anotherStart > anotherEnd || anotherStart > size -  || anotherEnd >= size)
                     {
                         Response.Headers["Content-Range"] = "bytes " + start + "-" + end + "/" + size;
                         Response.StatusCode = ;

                     }
                     start = anotherStart;
                     end = anotherEnd;
                     length = end - start + ; // Calculate new content length
                     reader.Read(bytes, start, length);
                     Response.StatusCode = ;
                 }
                 else
                 {
                     reader.Read(bytes, , bytes.Length);
                 }
                 Mstream = new MemoryStream(bytes);
             }
             Response.Headers["Content-Range"] = "bytes " + start + "-" + end + "/" + size;
             Response.Headers["Content-Length"] = length.ToString();
             Response.Headers.Add("Content-Disposition", "attachment; filename=download.wav");
             return new FileStreamResult(Mstream, "applicaton/octet-stream");
         }

.netcore 2.2 修改版本