Develop Reference

Saving MemoryStream to File produces 0 bytes

I'm using this code to write an MP3 MemoryStream to file:
using (var nSpeakStreamAsMp3 = new MemoryStream())
using (var nWavFileReader = new WaveFileReader(nSpeakStream))
using (var nMp3Writer = new LameMP3FileWriter(nSpeakStreamAsMp3, nWavFileReader.WaveFormat, LAMEPreset.STANDARD_FAST))
{
nWavFileReader.CopyTo(nMp3Writer);
string sPath = "C:\\inetpub\\wwwroot\\server\\bin\\mymp3.mp3";
using (FileStream nFile = new FileStream(sPath, FileMode.Create, System.IO.FileAccess.Write))
{
nSpeakStreamAsMp3.CopyTo(nFile);
}
sRet = (String.Concat("data:audio/mpeg;base64,", Convert.ToBase64String(nSpeakStreamAsMp3.ToArray())));
}
return sRet;
For some reason which I don't see, this produces a file of 0 bytes.
However, the MP3 stream is valid and does work. I'm passing it as a Base64String to a website, and I do hear it.
Where might be the error here?

nSpeakStreamAsMp3 is currently positioned at the end of the stream; you need to think like a VCR: be kind, rewind (nSpeakStreamAsMp3.Position = 0;) before you copy the value out again
make sure you flush nMp3Writer; if possible, close nMp3Writer completely

BinaryFormatter.Serialize( Image ) - ExternalException - A generic error occurred in GDI+

When I try to Serialize some images using the BinaryFormatter, I'll get a ExternalException - A generic error occurred in GDI+." After scratching my head for awhile, I decided to create a simple test project to narrow down the problem:
static void Main(string[] args)
{
string file = #"C:\temp\delme.jpg";
//Image i = new Bitmap(file);
//using(FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read))
byte[] data = File.ReadAllBytes(file);
using(MemoryStream originalms = new MemoryStream(data))
{
using (Image i = Image.FromStream(originalms))
{
BinaryFormatter bf = new BinaryFormatter();
using (MemoryStream ms = new MemoryStream())
{
// Throws ExternalException on Windows 7, not Windows XP
bf.Serialize(ms, i);
}
}
}
}
For specific images, I've tried all sorts of ways of loading the image and I could not get it to work under Windows 7, even when running the program as Administrator.
I've copied the exact same executable and image into my Windows XP VMWare instance and I have no problems.
Anyone have any idea of why for some images it doesn't work under Windows 7, but works under XP?
Here's one of the images:
http://www.2shared.com/file/7wAXL88i/SO_testimage.html
delme.jpg md5: 3d7e832db108de35400edc28142a8281

As the OP pointed out, the code provided throws an exception that seems to be occurring only with the image he provided but works fine with other images on my machine.
Option 1
static void Main(string[] args)
{
string file = #"C:\Users\Public\Pictures\delme.jpg";
byte[] data = File.ReadAllBytes(file);
using (MemoryStream originalms = new MemoryStream(data))
{
using (Image i = Image.FromStream(originalms))
{
BinaryFormatter bf = new BinaryFormatter();
using (MemoryStream ms = new MemoryStream())
{
// Throws ExternalException on Windows 7, not Windows XP
//bf.Serialize(ms, i);
i.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp); // Works
i.Save(ms, System.Drawing.Imaging.ImageFormat.Png); // Works
i.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); // Fails
}
}
}
}
It could be that the image in question was created with a tool that added some additional information that is interfering with the JPEG serialization.
P.S. The image can be saved to memory stream using BMP or PNG format. If changing the format is an option, then you can try out either of these or any other format defined in ImageFormat.
Option 2
If your goal is just to get the contents of the image file into a memory stream, then doing just the following would help
static void Main(string[] args)
{
string file = #"C:\Users\Public\Pictures\delme.jpg";
using (FileStream fileStream = File.OpenRead(file))
{
MemoryStream memStream = new MemoryStream();
memStream.SetLength(fileStream.Length);
fileStream.Read(memStream.GetBuffer(), 0, (int)fileStream.Length);
}
}

Although the Bitmap class is marked as [Serializable], it does not actually support serialisation. The best you can do is serialise the byte[] containing the raw image data and then re-create it using a MemoryStream and the Image.FromStream() method.
I can't explain the inconsistent behaviour you're experiencing; for me, it fails unconditionally (although I first discovered this when trying to marshal images between different app domains, rather than manually serialising them).

I don't know for sure but I would lean towards different security models for XP vs Windows 7. Image inherits from System.MarshalByRefObject. There is probably proxying going on between application domains when serialization is performed. This proxying might be forbidden in Windows 7.
http://msdn.microsoft.com/en-us/library/system.marshalbyrefobject%28v=vs.71%29.aspx

Decompressing using GZipStream returns only the first line

I’ve been working on a function parsing 3rd party fms logs. The logs are in Gzip, so I use a decompressing function that works for any other Gzip files we use.
When decompressing these files I only get the first line of the compressed file, there’s no exception, it just doesn’t find the rest of the bytes as if there's an EOF at the first line.
I tried using Ionic.Zlib instead of System.IO.Compression but the result was the same. The files don’t seem to be corrupted in any way, decompressing them with Winrar works.
If anybody has any idea of how to solve this, I’ll appreciate your help.
Thanks
You can download a sample file here:
http://www.adjustyourset.tv/fms_6F9E_20120621_0001.log.gz
This is my decompression function:
public static bool DecompressGZip(String fileRoot, String destRoot)
{
try
{
using (FileStream fileStram = new FileStream(fileRoot, FileMode.Open, FileAccess.Read))
{
using (FileStream fOutStream = new FileStream(destRoot, FileMode.Create, FileAccess.Write))
{
using (GZipStream zipStream = new GZipStream(fileStram, CompressionMode.Decompress, true))
{
byte[] buffer = new byte[4096];
int numRead;
while ((numRead = zipStream.Read(buffer, 0, buffer.Length)) != 0)
{
fOutStream.Write(buffer, 0, numRead);
}
return true;
}
}
}
}
catch (Exception ex)
{
LogUtils.SaveToLog(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"), "Eror decompressing " + fileRoot + " : " + ex.Message, Constants.systemLog, 209715200, 6);
return false;
}
}

I've put the last 45 minutes wrapping my head around this problem but I just can't explain why it isn't working. Somehow the DeflateStream-class isn't decoding your data properly. I wrote up my own GZip-parser (I can share the code if anyone wants to check it) which reads all the headers and checks them for validity (to make sure that there are no funny stuff there) and then use DeflateStream to inflate the actual data but with your file it still just gets me the first line.
If I recompress using your logfile using GZipStream (after first decompressing it with winrar) then it is decompressed just fine again both my my own parser and your own sample.
There seems to be some critizism on the net about Microsofts implementation of Deflate (http://www.virtualdub.org/blog/pivot/entry.php?id=335) so it might be that you found one of it's quirks.
However, a simple solution to your problem is to switch to SharZipLib (http://www.icsharpcode.net/opensource/sharpziplib/), I tried it out and it can decompress your file just fine.
public static void DecompressGZip(String fileRoot, String destRoot)
{
using (FileStream fileStram = new FileStream(fileRoot, FileMode.Open, FileAccess.Read))
using (GZipInputStream zipStream = new GZipInputStream(fileStram))
using (StreamReader sr = new StreamReader(zipStream))
{
string data = sr.ReadToEnd();
File.WriteAllText(destRoot, data);
}
}

Why is compressed then uncompressed stream of different length

I'm using the SevenZipSharp library to compress and then uncompress a MemoryStream which contains a simple serialized object. However, the compressed and decompressed streams are of different length.
From the code run below I get
Input length: 174
Output length: 338
(the SevenZipSharp dll is included as a reference and the 7z.dll is included in the project output)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
namespace DataTransmission {
class Program {
static void Main(string[] args)
{
SevenZip.SevenZipCompressor compressor = new SevenZip.SevenZipCompressor();
//compressor.CompressionMethod = SevenZip.CompressionMethod.Lzma2;
//compressor.CompressionLevel = SevenZip.CompressionLevel.Normal;
MemoryStream inputStream = new MemoryStream();
Person me = new Person("John", "Smith");
BinaryFormatter formatter = new BinaryFormatter();
formatter.Serialize(inputStream, me);
Int32 inputStreamLength = (Int32)inputStream.Length;
MemoryStream outputStream = new MemoryStream();
compressor.CompressStream(inputStream, outputStream);
SevenZip.SevenZipExtractor decompressor = new SevenZip.SevenZipExtractor(outputStream);
decompressor.ExtractFile(0, outputStream);
Int32 outputStreamLength = (Int32)outputStream.Length;
Console.WriteLine("Input length: {0}", inputStreamLength);
Console.WriteLine("Output length: {0}", outputStreamLength);
Console.ReadLine();
}
}
[Serializable]
public class Person {
public string firstName;
public string lastName;
public Person(string fname, string lname) {
firstName = fname;
lastName = lname;
}
}
}
Can anyone help me with why this may be?
Thanks,

You've decompressed into outputStream despite that already containing data. You should use a new MemoryStream for the output.
(In fact, it's very odd because the decompressor is reading from outputStream and also writing to outputStream. Bad idea. Use two different streams.)
You should also rewind each stream after you've written to it and before something else wants to read it, e.g. with
inputStream.Position = 0;
It's possible that SevenZipLib is doing that for you in this case, but in general if you want something to act from the start of the stream, you should reset it appropriately.
I've just made the following change to your code, at which point I get the same length for input and output:
MemoryStream targetStream = new MemoryStream();
decompressor.ExtractFile(0, targetStream);
Int32 outputStreamLength = (Int32)targetStream.Length;
As I say, you should make the appropriate other changes too.

However, the compressed and decompressed streams are of different length
That is the whole purpose of compression ...
Look at this piece of the code:
SevenZip.SevenZipExtractor decompressor =
new SevenZip.SevenZipExtractor(outputStream);
decompressor.ExtractFile(0, outputStream);
You are decompressing from outputStream to outputStream. It will probably fail with larger data. Make changes so that it reads
SevenZip.SevenZipExtractor decompressor =
new SevenZip.SevenZipExtractor(compressedStream);
decompressor.ExtractFile(0, outputStream);

Image.Save(..) throws a GDI+ exception because the memory stream is closed

i've got some binary data which i want to save as an image. When i try to save the image, it throws an exception if the memory stream used to create the image, was closed before the save. The reason i do this is because i'm dynamically creating images and as such .. i need to use a memory stream.
this is the code:
[TestMethod]
public void TestMethod1()
{
// Grab the binary data.
byte[] data = File.ReadAllBytes("Chick.jpg");
// Read in the data but do not close, before using the stream.
Stream originalBinaryDataStream = new MemoryStream(data);
Bitmap image = new Bitmap(originalBinaryDataStream);
image.Save(#"c:\test.jpg");
originalBinaryDataStream.Dispose();
// Now lets use a nice dispose, etc...
Bitmap2 image2;
using (Stream originalBinaryDataStream2 = new MemoryStream(data))
{
image2 = new Bitmap(originalBinaryDataStream2);
}
image2.Save(#"C:\temp\pewpew.jpg"); // This throws the GDI+ exception.
}
Does anyone have any suggestions to how i could save an image with the stream closed? I cannot rely on the developers to remember to close the stream after the image is saved. In fact, the developer would have NO IDEA that the image was generated using a memory stream (because it happens in some other code, elsewhere).
I'm really confused :(

As it's a MemoryStream, you really don't need to close the stream - nothing bad will happen if you don't, although obviously it's good practice to dispose anything that's disposable anyway. (See this question for more on this.)
However, you should be disposing the Bitmap - and that will close the stream for you. Basically once you give the Bitmap constructor a stream, it "owns" the stream and you shouldn't close it. As the docs for that constructor say:
You must keep the stream open for the
lifetime of the Bitmap.
I can't find any docs promising to close the stream when you dispose the bitmap, but you should be able to verify that fairly easily.

A generic error occurred in GDI+.
May also result from incorrect save path!
Took me half a day to notice that.
So make sure that you have double checked the path to save the image as well.

Perhaps it is worth mentioning that if the C:\Temp directory does not exist, it will also throw this exception even if your stream is still existent.

Copy the Bitmap. You have to keep the stream open for the lifetime of the bitmap.
When drawing an image: System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI
public static Image ToImage(this byte[] bytes)
{
using (var stream = new MemoryStream(bytes))
using (var image = Image.FromStream(stream, false, true))
{
return new Bitmap(image);
}
}
[Test]
public void ShouldCreateImageThatCanBeSavedWithoutOpenStream()
{
var imageBytes = File.ReadAllBytes("bitmap.bmp");
var image = imageBytes.ToImage();
image.Save("output.bmp");
}

I had the same problem but actually the cause was that the application didn't have permission to save files on C. When I changed to "D:\.." the picture has been saved.

You can try to create another copy of bitmap:
using (var memoryStream = new MemoryStream())
{
// write to memory stream here
memoryStream.Position = 0;
using (var bitmap = new Bitmap(memoryStream))
{
var bitmap2 = new Bitmap(bitmap);
return bitmap2;
}
}

This error occurred to me when I was trying from Citrix. The image folder was set to C:\ in the server, for which I do not have privilege. Once the image folder was moved to a shared drive, the error was gone.

A generic error occurred in GDI+. It can occur because of image storing paths issues,I got this error because my storing path is too long, I fixed this by first storing the image in a shortest path and move it to the correct location with long path handling techniques.

I was getting this error, because the automated test I was executing, was trying to store snapshots into a folder that didn't exist. After I created the folder, the error resolved

One strange solution which made my code to work.
Open the image in paint and save it as a new file with same format(.jpg). Now try with this new file and it works. It clearly explains you that the file might be corrupted in someway.
This can help only if your code has every other bugs fixed

It has also appeared with me when I was trying to save an image into path
C:\Program Files (x86)\some_directory
and the .exe wasn't executed to run as administrator, I hope this may help someone who has same issue too.

For me the code below crashed with A generic error occurred in GDI+on the line which Saves to a MemoryStream. The code was running on a web server and I resolved it by stopping and starting the Application Pool that was running the site.
Must have been some internal error in GDI+
private static string GetThumbnailImageAsBase64String(string path)
{
if (path == null || !File.Exists(path))
{
var log = ContainerResolver.Container.GetInstance<ILog>();
log.Info($"No file was found at path: {path}");
return null;
}
var width = LibraryItemFileSettings.Instance.ThumbnailImageWidth;
using (var image = Image.FromFile(path))
{
using (var thumbnail = image.GetThumbnailImage(width, width * image.Height / image.Width, null, IntPtr.Zero))
{
using (var memoryStream = new MemoryStream())
{
thumbnail.Save(memoryStream, ImageFormat.Png); // <= crash here
var bytes = new byte[memoryStream.Length];
memoryStream.Position = 0;
memoryStream.Read(bytes, 0, bytes.Length);
return Convert.ToBase64String(bytes, 0, bytes.Length);
}
}
}
}

I came across this error when I was trying a simple image editing in a WPF app.
Setting an Image element's Source to the bitmap prevents file saving.
Even setting Source=null doesn't seem to release the file.
Now I just never use the image as the Source of Image element, so I can overwrite after editing!
EDIT
After hearing about the CacheOption property(Thanks to #Nyerguds) I found the solution:
So instead of using the Bitmap constructor I must set the Uri after setting CacheOption BitmapCacheOption.OnLoad.(Image1 below is the Wpf Image element)
Instead of
Image1.Source = new BitmapImage(new Uri(filepath));
Use:
var image = new BitmapImage();
image.BeginInit();
image.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
image.CacheOption = BitmapCacheOption.OnLoad;
image.UriSource = new Uri(filepath);
image.EndInit();
Image1.Source = image;
See this: WPF Image Caching

Try this code:
static void Main(string[] args)
{
byte[] data = null;
string fullPath = #"c:\testimage.jpg";
using (MemoryStream ms = new MemoryStream())
using (Bitmap tmp = (Bitmap)Bitmap.FromFile(fullPath))
using (Bitmap bm = new Bitmap(tmp))
{
bm.SetResolution(96, 96);
using (EncoderParameters eps = new EncoderParameters(1))
{
eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
bm.Save(ms, GetEncoderInfo("image/jpeg"), eps);
}
data = ms.ToArray();
}
File.WriteAllBytes(fullPath, data);
}
private static ImageCodecInfo GetEncoderInfo(string mimeType)
{
ImageCodecInfo[] encoders = ImageCodecInfo.GetImageEncoders();
for (int j = 0; j < encoders.Length; ++j)
{
if (String.Equals(encoders[j].MimeType, mimeType, StringComparison.InvariantCultureIgnoreCase))
return encoders[j];
}
return null;
}

I used imageprocessor to resize images and one day I got "A generic error occurred in GDI+" exception.
After looked up a while I tried to recycle the application pool and bingo it works. So I note it here, hope it help ;)
Cheers

I was getting this error today on a server when the same code worked fine locally and on our DEV server but not on PRODUCTION. Rebooting the server resolved it.

public static byte[] SetImageToByte(Image img)
{
ImageConverter converter = new ImageConverter();
return (byte[])converter.ConvertTo(img, typeof(byte[]));
}
public static Bitmap SetByteToImage(byte[] blob)
{
MemoryStream mStream = new MemoryStream();
byte[] pData = blob;
mStream.Write(pData, 0, Convert.ToInt32(pData.Length));
Bitmap bm = new Bitmap(mStream, false);
mStream.Dispose();
return bm;
}