public async Task<IHttpActionResult> DownloadCourseModuleClip(string clipname, ClipToSave clipToSave)
{
string clipUrl = string.Empty;
// 1- get the video clip url to download.
try
{
clipUrl = GetClipUrl(clipToSave);
// 2- make sure the folders structure exist.
var videoSaveDirectory = SetUpVideoFolderStructure(clipToSave.CourseTitle,
(clipToSave.ModuleIndex + 1).ToString("D2") + " - " + clipToSave.ModuleTitle,
(clipToSave.ClipIndex + 1).ToString("D2") + " - " + clipToSave.Title);
// 3- download the video and report progress back.
int receivedBytes = 0;
long totalBytes = 0;
var videoFileName = ((clipToSave.ClipIndex + 1).ToString("D2") + " - " + clipToSave.Title + ".mp4").ToValidFileName();
var videoSaveLocation = videoSaveDirectory.FullName + "\\raw-" + videoFileName;
using (var client = new WebClient())
using (var regStream = await client.OpenReadTaskAsync(clipUrl))
using (var stream = new ThrottledStream(regStream, 115200))
{
byte[] buffer = new byte[1024];
totalBytes = Int32.Parse(client.ResponseHeaders[HttpResponseHeader.ContentLength]);
stream.MaximumBytesPerSecond = GetClipMaxDownloadSpeed(clipToSave.DurationSeconds, totalBytes);
using (var fileStream = File.OpenWrite(videoSaveLocation))
{
for (;;)
{
int bytesRead = await stream.ReadAsync(buffer, 0, buffer.Length);
if (bytesRead == 0)
{
await Task.Yield();
break;
}
receivedBytes += bytesRead;
var progress = new ProgressArgs()
{
Id = clipToSave.Name,
BytesReceived = receivedBytes,
FileName = videoFileName,
TotalBytes = totalBytes,
IsDownloading = true,
Extra = new { clipToSave.ModuleIndex, clipToSave.ClipIndex }
};
fileStream.Write(buffer, 0, bytesRead);
var hubContext = GlobalHost.ConnectionManager.GetHubContext<ProgressHub>();
hubContext.Clients.All.updateProgress(progress);
}
}
}
// 4- save the video file.
var inputFile = new MediaFile { Filename = videoSaveDirectory.FullName + "\\raw-" + videoFileName };
var outputFile = new MediaFile { Filename = videoSaveDirectory.FullName + "\\" + videoFileName };
File.Move(inputFile.Filename, outputFile.Filename);
// 5- Create srt files
if (Constants.SUBTITLES)
{
var srtFilename = outputFile.Filename.Substring(0, outputFile.Filename.Length - 4) + ".srt";
var srtString = clipToSave.TranscriptClip.GetSrtString(clipToSave.DurationSeconds);
File.WriteAllText(srtFilename, srtString);
}
return Ok(new ProgressArgs()
{
Id = clipToSave.Name,
BytesReceived = receivedBytes,
FileName = videoFileName,
TotalBytes = totalBytes,
IsDownloading = false,
Extra = new { clipToSave.ModuleIndex, clipToSave.ClipIndex }
});
}
catch (Exception exception)
{
return HandleException(exception);
}
}
private string GetClipUrl(ClipToSave clip)
{
var http = (HttpWebRequest)WebRequest.Create(new Uri(Constants.COURSE_CLIP_DATA_URL));
http.Accept = "application/json";
http.ContentType = "application/json";
http.Method = "POST";
http.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0";
var playerParameters = HttpUtility.ParseQueryString(clip.PlayerParameters);
var playerParametersObj = new
{
a = playerParameters["author"],
m = playerParameters["name"],
course = playerParameters["course"],
cn = playerParameters["clip"],
mt = "mp4",
q = (clip.SupportsWideScreenVideoFormats ? "1280x720" : "1024x768"),
cap = false,
lc = "en"
};
var encoding = new ASCIIEncoding();
Byte[] dataBytes = encoding.GetBytes(JsonConvert.SerializeObject(playerParametersObj));
using (Stream sendStream = http.GetRequestStream())
sendStream.Write(dataBytes, 0, dataBytes.Length);
// if the clip is not free, then the user must sign in first and set authentication cookie.
if (!clip.UserMayViewClip)
SetupAuthenticationCookie(http);
try
{
using (var response = http.GetResponse())
using (var receiveStream = response.GetResponseStream())
using (var sr = new StreamReader(receiveStream))
{
var clipurl = sr.ReadToEnd();
return clipurl;
}
}
catch
{
logger.Error("Couldn't retrieve clip URL. Request parameters={0}", JsonConvert.SerializeObject(playerParametersObj));
throw new Exception("Couldn't retrieve clip URL. Please check log file.");
}
}
