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Reading a MemoryStream containing opus audio with NAudio

I'm trying to play opus audio files from web which I try to buffer with a MemoryStream. I'm aware of NAudio's ability to take urls however I need to set cookies and user agent before I access the file so this eliminates that option.
My latest approach was to buffer 30~ seconds of stream, feed it to StreamMediaFoundationReader and write to the same MemoryStream when needed, however NAudio ends up playing the initial buffered segment and stop after that is completed. What would be the correct approach for this?
Here's my current code if needed. (I have no idea how audio streaming works so please go easy on me)
bufstr.setReadStream(httpreq.GetResponse().GetResponseStream()); //bufstr is a custom class which creates a memorystream I can write to.
StreamMediaFoundationReader streamread = new StreamMediaFoundationReader(bufstr.getStream());
bufstr.readToStream(); //get the initial 30~ seconds of content
waveOut.Init(streamread);
waveOut.Play();
int seconds = 0;
while(waveOut.PlaybackState == PlaybackState.Playing) {
Thread.Sleep(1000);
seconds++;
if (secs % 30 > 15) bufstr.readToStream();
}
bufstr's readToStream method
public void readToStream() {
int prevbufcount = totalbuffered; //I keep track of how many bytes I fetched from remote url.
while (stream.CanRead && prevbufcount + (30 * (this.bitrate / 8)) > totalbuffered && totalbuffered != contentlength) { //read around 30 seconds of content;
Console.Write($"Caching {prevbufcount + (30 * (this.bitrate / 8))}/{totalbuffered}\r");
byte[] buf = new byte[1024];
bufferedcount = stream.Read(buf, 0, 1024);
totalbuffered += bufferedcount;
memorystream.Write(buf, 0, bufferedcount);
}
}

While debugging I found out that content length I get from server does not match with the actual size of stream, so I ended up calculating content length via other details I get from server.
The issue might also be a race condition due to the fact that it stopped after I manually kept track of where I write on memory stream

Stream on the fly decompressing causes artifacts when buffer is larger than 1byte

I am currently testing several decompression libraries for a project I'm involved with to decompress http file streams on the fly. I have tried two very promising libraries and found an issue that seems to appear in both of them.
This is what I am doing:
video.avi compressed to video.zip on HTTP server test.com/video.zip (~20MB)
HttpWebRequest to read stream from the server
Write HttpWebRequest ResponseStream data into MemoryStream
Let decompression library read from MemoryStream
Read decompressed file stream while it's being downloaded by HttpWebRequest
The whole idea works fine, I'm able to uncompress and stream the compressed video directly into VLC stdin and it's rendered just fine. However I have to use a read buffer of one byte on the decompression library. Any buffer larger than one byte will cause the uncompressed data stream to be cut off. For a test I've written the decompressed stream into a file and compared it with the original video.avi and some data is just skipped by the decompression. When streaming this broken data into VLC it causes a lot of video artifacts and the playback speed is also greatly reduced.
If I knew the size of what is available to read I could trim my buffer accordingly but no library would make this information public so all I can do is read the data with a one byte buffer. Maybe my approach is wrong? Or maybe I'm overlooking something?
Here's an example code (requires VLC):
ICSharpCode.SharpZLib (http://icsharpcode.github.io/SharpZipLib/)
static void Main(string[] args)
{
// Initialise VLC
Process vlc = new Process()
{
StartInfo =
{
FileName = #"C:\Program Files\VideoLAN\vlc.exe", // Adjust as required to test the code
RedirectStandardInput = true,
UseShellExecute = false,
Arguments = "-"
}
};
vlc.Start();
Stream outStream = vlc.StandardInput.BaseStream;
// Get source stream
HttpWebRequest stream = (HttpWebRequest)WebRequest.Create("http://codefreak.net/~daniel/apps/stream60s-large.zip");
Stream compressedVideoStream = stream.GetResponse().GetResponseStream();
// Create local decompression loop
MemoryStream compressedLoopback = new MemoryStream();
ZipInputStream zipStream = new ZipInputStream(compressedLoopback);
ZipEntry currentEntry = null;
byte[] videoStreamBuffer = new byte[8129]; // 8kb read buffer
int read = 0;
long totalRead = 0;
while ((read = compressedVideoStream.Read(videoStreamBuffer, 0, videoStreamBuffer.Length)) > 0)
{
// Write compressed video stream into compressed loopback without affecting current read position
long previousPosition = compressedLoopback.Position; // Store current read position
compressedLoopback.Position = totalRead; // Jump to last write position
totalRead += read; // Increase last write position by current read size
compressedLoopback.Write(videoStreamBuffer, 0, read); // Write data into loopback
compressedLoopback.Position = previousPosition; // Restore reading position
// If not already, move to first entry
if (currentEntry == null)
currentEntry = zipStream.GetNextEntry();
byte[] outputBuffer = new byte[1]; // Decompression read buffer, this is the bad one!
int zipRead = 0;
while ((zipRead = zipStream.Read(outputBuffer, 0, outputBuffer.Length)) > 0)
outStream.Write(outputBuffer, 0, outputBuffer.Length); // Write directly to VLC stdin
}
}
SharpCompress (https://github.com/adamhathcock/sharpcompress)
static void Main(string[] args)
{
// Initialise VLC
Process vlc = new Process()
{
StartInfo =
{
FileName = #"C:\Program Files\VideoLAN\vlc.exe", // Adjust as required to test the code
RedirectStandardInput = true,
UseShellExecute = false,
Arguments = "-"
}
};
vlc.Start();
Stream outStream = vlc.StandardInput.BaseStream;
// Get source stream
HttpWebRequest stream = (HttpWebRequest)WebRequest.Create("http://codefreak.net/~daniel/apps/stream60s-large.zip");
Stream compressedVideoStream = stream.GetResponse().GetResponseStream();
// Create local decompression loop
MemoryStream compressedLoopback = new MemoryStream();
ZipReader zipStream = null;
EntryStream currentEntry = null;
byte[] videoStreamBuffer = new byte[8129]; // 8kb read buffer
int read = 0;
long totalRead = 0;
while ((read = compressedVideoStream.Read(videoStreamBuffer, 0, videoStreamBuffer.Length)) > 0)
{
// Write compressed video stream into compressed loopback without affecting current read position
long previousPosition = compressedLoopback.Position; // Store current read position
compressedLoopback.Position = totalRead; // Jump to last write position
totalRead += read; // Increase last write position by current read size
compressedLoopback.Write(videoStreamBuffer, 0, read); // Write data into loopback
compressedLoopback.Position = previousPosition; // Restore reading position
// Open stream after writing to it because otherwise it will not be able to identify the compression type
if (zipStream == null)
zipStream = (ZipReader)ReaderFactory.Open(compressedLoopback); // Cast to ZipReader, as we know the type
// If not already, move to first entry
if (currentEntry == null)
{
zipStream.MoveToNextEntry();
currentEntry = zipStream.OpenEntryStream();
}
byte[] outputBuffer = new byte[1]; // Decompression read buffer, this is the bad one!
int zipRead = 0;
while ((zipRead = currentEntry.Read(outputBuffer, 0, outputBuffer.Length)) > 0)
outStream.Write(outputBuffer, 0, outputBuffer.Length); // Write directly to VLC stdin
}
}
To test this code I recommend setting the output buffer for SharpZipLib to 2 bytes and for SharpCompress to 8 bytes. You will see the artifacts and also that the play speed of the video is wrong, the seek time should always be aligned with the number that is counting in the video.
I haven't really found any good explanation of why a larger outputBuffer that is reading from the decompression lib is causing these problems or a way to solve this other than having the tiniest possible buffer.
So my question is what I am doing wrong or if this is a general issue when reading compressed files from streams? How could I increase the outputBuffer while reading the correct data?
Any help is greatly appreciated!
Regards,
Gachl

You need to write only how many bytes you read. Writing the entire buffer size will add additional bytes (whatever happened to be in the buffer before). zipStream.Read is not required to read as many bytes as you request.
while ((zipRead = zipStream.Read(outputBuffer, 0, outputBuffer.Length)) > 0)
outStream.Write(outputBuffer, 0, zipRead); // Write directly to VLC stdin

How to cancel large file download yet still get page source in C#?

I'm working in C# on a program to list all course resources for a MOOC (e.g. Coursera). I don't want to download the content, just get a listing of all the resources (e.g. pdf, videos, text files, sample files, etc...) which are made available to the course.
My problem lies in parsing the html source (currently using HtmlAgilityPack) without downloading all the content.
For example, if you go to this intro video for a banking course on Coursera and check the source (F12 in Chrome for Developer Tools), you can see the page source. I can stop the video download which autoplays, but still see the source.
How can I get the source in C# without download all the content?
I've looked in the HttpWebRequest headers (problem: time out), and DownloadDataAsync with Cancel (problem: the Completed Result object is invalid when cancelling the async request). I've also tried various Loads from HtmlAgilityPack but with no success.
Time out:
HttpWebRequest postRequest = (HttpWebRequest)WebRequest.Create(url);
postRequest.Timeout = TIMEOUT * 1000000; //Really long
postRequest.Referer = "https://www.coursera.org";
if (headers != null)
{ //headers here }
//Deal with cookies
if (cookie != null)
{ cookieJar.Add(cookie); }
postRequest.CookieContainer = cookiejar;
postRequest.Method = "GET";
postRequest.AllowAutoRedirect = allowRedirect;
postRequest.ServicePoint.Expect100Continue = true;
HttpWebResponse postResponse = (HttpWebResponse)postRequest.GetResponse();
Any tips on how to proceed?

There are at least two ways to do what you're asking. The first is to use a range get. That is, specify the range of the file you want to read. You do that by calling AddRange on the HttpWebRequest. So if you want, say, the first 10 kilobytes of the file, you'd write:
request.AddRange(-10240);
Read carefully what the documentation says about the meaning of that parameter. If it's negative, it specifies the ending point of the range. There are also other overloads of AddRange that you might be interested in.
Not all servers support range gets, though. If that doesn't work, you'll have to do it another way.
What you can do is call GetResponse and then start reading data. Once you've read as much data as you want, you can stop reading and close the stream. I've modified your sample slightly to show what I mean.
string url = "https://www.coursera.org/course/money";
HttpWebRequest postRequest = (HttpWebRequest)WebRequest.Create(url);
postRequest.Method = "GET";
postRequest.AllowAutoRedirect = true; //allowRedirect;
postRequest.ServicePoint.Expect100Continue = true;
HttpWebResponse postResponse = (HttpWebResponse) postRequest.GetResponse();
int maxBytes = 1024*1024;
int totalBytesRead = 0;
var buffer = new byte[maxBytes];
using (var s = postResponse.GetResponseStream())
{
int bytesRead;
// read up to `maxBytes` bytes from the response
while (totalBytesRead < maxBytes && (bytesRead = s.Read(buffer, 0, maxBytes)) != 0)
{
// Here you can save the bytes read to a persistent buffer,
// or write them to a file.
Console.WriteLine("{0:N0} bytes read", bytesRead);
totalBytesRead += bytesRead;
}
}
Console.WriteLine("total bytes read = {0:N0}", totalBytesRead);
That said, I ran this sample and it downloaded about 6 kilobytes and stopped. I don't know why you're having trouble with timeouts or too much data.
Note that sometimes trying to close the stream before the entire response is read will cause the program to hang. I'm not sure why that happens at all, and I can't explain why it only happens sometimes. But you can solve it by calling request.Abort before closing the stream. That is:
using (var s = postResponse.GetResponseStream())
{
// do stuff here
// abort the request before continuing
postRequest.Abort();
}

C#: how to read a line from a stream and then start reading it from beginning?

I need to read the first line from a stream to determine file's encoding, and then recreate the stream with that Encoding
The following code does not work correctly:
var r = response.GetResponseStream();
var sr = new StreamReader(r);
string firstLine = sr.ReadLine();
string encoding = GetEncodingFromFirstLine(firstLine);
string text = new StreamReader(r, Encoding.GetEncoding(encoding)).ReadToEnd();
The text variable doesn't contain the whole text. For some reason the first line and several lines after it are skipped.
I tried everything: closing the StreamReader, resetting it, calling a separate GetResponseStream... but nothing worked.
I can't get the response stream again as I'm getting this file from the internet, and redownloading it again would be bad performance wise.
Update
Here's what GetEncodingFromFirstLine() looks like:
public static string GetEncodingFromFirstLine(string line)
{
int encodingIndex = line.IndexOf("encoding=");
if (encodingIndex == -1)
{
return "utf-8";
}
return line.Substring(encodingIndex + "encoding=".Length).Replace("\"", "").Replace("'", "").Replace("?", "").Replace(">", "");
}
...
// true
Assert.AreEqual("windows-1251", GetEncodingFromFirstLine(#"<?xml version=""1.0"" encoding=""windows-1251""?>"));
** Update 2 **
I'm working with XML files, and the text variable is parsed as XML:
var feedItems = XElement.Parse(text);

Well you're asking it to detect the encoding... and that requires it to read data. That's reading it from the underlying stream, and you're then creating another StreamReader around the same stream.
I suggest you:
Get the response stream
Retrieve all the data into a byte array (or MemoryStream)
Detect the encoding (which should be performed on bytes, not text - currently you're already assuming UTF-8 by creating a StreamReader)
Create a MemoryStream around the byte array, and a StreamReader around that
It's not clear what your GetEncodingFromFirstLine method does... or what this file really is. More information may make it easier to help you.
EDIT: If this is to load some XML, don't reinvent the wheel. Just give the stream to one of the existing XML-parsing classes, which will perform the appropriate detection for you.

You need to change the current position in the stream to the beginning.
r.Position = 0;
string text = new StreamReader(r, Encoding.GetEncoding(encoding)).ReadToEnd();

I found the answer to my question here:
How can I read an Http response stream twice in C#?
Stream responseStream = CopyAndClose(resp.GetResponseStream());
// Do something with the stream
responseStream.Position = 0;
// Do something with the stream again
private static Stream CopyAndClose(Stream inputStream)
{
const int readSize = 256;
byte[] buffer = new byte[readSize];
MemoryStream ms = new MemoryStream();
int count = inputStream.Read(buffer, 0, readSize);
while (count > 0)
{
ms.Write(buffer, 0, count);
count = inputStream.Read(buffer, 0, readSize);
}
ms.Position = 0;
inputStream.Close();
return ms;
}

Slow performance in reading from stream .NET

I have a monitoring system and I want to save a snapshot from a camera when alarm trigger.
I have tried many methods to do that…and it’s all working fine , stream snapshot from the camera then save it as a jpg in the pc…. picture (jpg format,1280*1024,140KB)..That’s fine
But my problem is in the application performance...
The app need about 20 ~30 seconds to read the steam, that’s not acceptable coz that method will be called every 2 second .I need to know what wrong with that code and how I can get it much faster than that. ?
Many thanks in advance
Code:
string sourceURL = "http://192.168.0.211/cgi-bin/cmd/encoder?SNAPSHOT";
byte[] buffer = new byte[200000];
int read, total = 0;
WebRequest req = (WebRequest)WebRequest.Create(sourceURL);
req.Credentials = new NetworkCredential("admin", "123456");
WebResponse resp = req.GetResponse();
Stream stream = resp.GetResponseStream();
while ((read = stream.Read(buffer, total, 1000)) != 0)
{
total += read;
}
Bitmap bmp = (Bitmap)Bitmap.FromStream(new MemoryStream(buffer, 0,total));
string path = JPGName.Text+".jpg";
bmp.Save(path);

I very much doubt that this code is the cause of the problem, at least for the first method call (but read further below).
Technically, you could produce the Bitmap without saving to a memory buffer first, or if you don't need to display the image as well, you can save the raw data without ever constructing a Bitmap, but that's not going to help in terms of multiple seconds improved performance. Have you checked how long it takes to download the image from that URL using a browser, wget, curl or whatever tool, because I suspect something is going on with the encoding source.
Something you should do is clean up your resources; close the stream properly. This can potentially cause the problem if you call this method regularly, because .NET will only open a few connections to the same host at any one point.
// Make sure the stream gets closed once we're done with it
using (Stream stream = resp.GetResponseStream())
{
// A larger buffer size would be benefitial, but it's not going
// to make a significant difference.
while ((read = stream.Read(buffer, total, 1000)) != 0)
{
total += read;
}
}

I cannot try the network behavior of the WebResponse stream, but you handle the stream twice (once in your loop and once with your memory stream).
I don't thing that's the whole problem but I'd give it a try:
string sourceURL = "http://192.168.0.211/cgi-bin/cmd/encoder?SNAPSHOT";
WebRequest req = (WebRequest)WebRequest.Create(sourceURL);
req.Credentials = new NetworkCredential("admin", "123456");
WebResponse resp = req.GetResponse();
Stream stream = resp.GetResponseStream();
Bitmap bmp = (Bitmap)Bitmap.FromStream(stream);
string path = JPGName.Text + ".jpg";
bmp.Save(path);

Try to read bigger pieces of data, than 1000 bytes per time. I can see no problem with, for example,
read = stream.Read(buffer, 0, buffer.Length);

Try this to download the file.
using(WebClient webClient = new WebClient())
{
webClient.DownloadFile("http://192.168.0.211/cgi-bin/cmd/encoder?SNAPSHOT", "c:\\Temp\myPic.jpg");
}
You can use a DateTime to put a unique stamp on the shot.