Android :: Fast Way To Compress Binary Data?
Nov 2, 2010
I have some binary data (pixel values) in a int[] (or a byte[] if you prefer) that I want to write to disk in an Android app. I only want to use a small amount of processing time but want as much compression as I can for this. What are my options?In many cases the array will contain lots of consecutive zeros so something simple and fast like RLE compression would probably work well. I can't see any Android API functions for this though. If I have to loop over the array in Java, this will be very slow as there is no JIT on most Android devices. I could use the NDK but I'd rather avoid this if I can.
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Sep 15, 2010
In my Android app I want to have an input field with autocomplete. The number of items will be about 300000. The best solution seems to be to put the items into a file (on sdcard), one item per line, each line would have the same number of characters so that I can seek to specific line number. If the user enters something in the text field, I would binary search (via RandomAccessFile) the file and show suggestions.I want the autocomplete to be super fast (ideally under 100ms but I guess it's impossible), what optimizations I can do?
Update 1:
I will convert the users input to lowercase english characters (a-z) with spaces. So 'A/b' would be converted to 'a b' and then searched.
Uodate 2:
I now realized I need additional thing - to search for word-starting substrings.
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Mar 11, 2010
I am porting a Python application to Android and, at some point, this application has to communicate with a Web Service, sending it compressed data. In order to do that it uses the next method:
def stuff(self, data): "Convert into UTF-8 and compress."
return zlib.compress(simplejson.dumps(data))
I am using the next method to try to emulate this behavior in Android:
private String compressString(String stringToCompress) { Log.i(TAG, "Compressing String " + stringToCompress);
byte[] input = stringToCompress.getBytes();
// Create the compressor with highest level of compression Deflater compressor = new Deflater();
//compressor.setLevel(Deflater.BEST_COMPRESSION);
// Give the compressor the data to compress compressor.setInput(input); compressor.finish();
// Create an expandable byte array to hold the compressed data.
// You cannot use an array that's the same size as the orginal because
// there is no guarantee that the compressed data will be smaller than
// the uncompressed data.
ByteArrayOutputStream bos = new ByteArrayOutputStream(input.length);
// Compress the data byte[] buf = new byte[1024];
while (!compressor.finished()) { int count = compressor.deflate(buf);
bos.write(buf, 0, count); } try { bos.close();
} catch (IOException e) { } // Get the compressed data byte[] compressedData = bos.toByteArray();
Log.i(TAG, "Finished to compress string " + stringToCompress);
return new String(compressedData);
}
But the HTTP response from the server is not correct and I guess it is because the result of the compression in Java is not the same as the one in Python. I ran a little test compressing "a" both with zlib.compress and deflate.
Python, zlib.compress() -> x%9CSJT%02%00%01M%00%A6
Android, Deflater.deflate -> H%EF%BF%BDK%04%00%00b%00b
How should I compress the data in Android to obtain the same value of zlib.compress() in Python?
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Feb 17, 2012
I know the best way to get more space in my phone is to get a bigger sd card...but i was wondering is there a way to compress all the data in the phone and on the sd card, i would like to compress everything i have and not get rid of anything.....i dont have much on my phone at all and every now and then i get a notification that im running low on disk space so i have to go threw and delete things and move things to the sd card even though i have the phone set to install to sd card...
i have a rooted samsung admire.
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May 4, 2013
I'm looking for some apps which can let me compress the data because my ISP provides unlimited 3G although the speed drops to 15kilobytes/s (not to be confused with kilobits) after 500MB of usage. Is it possible that i can compress the data usage with an app so that it takes longer for me to use 500MB.
Also i mostly listen to music videos on youtube as i'm driving around so are there any other alternative apps which allow me to listen to music but can run on a speed of 15kB/s?
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Jun 15, 2010
Android supports a limited version of apache's http client(v4). typically if I want to send binary data using content type= application/octet-stream via POST,
I do the following:
CODE:.........................
However ByteArrayRequestEntity is not supported on android. what can I do?
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Jul 8, 2010
I'm looking for some input on how to go about a problem I have. We have a device that has binary data that it needs to send out (they are mainly just symbols, but in a custom binary format) over ethernet. I need to intercept this data on the phone and display the symbols over google maps. I'm just wondering the best way to go about this, I have a few ideas but am not sure if they are possible or feasable: 1. Is it possible for the phone to connect directly to the device if the device had some sort of server running on it, then poll for new data? If so, what is the protocol needed to be able to direct connect like that? 2. Perhaps modify the device software to send data to the phone(s) in SMS data message format? Im not sure if it is possible for software to "spoof" an SMS to a phone when it is not a phone itself? 3. Have the device software upload all its binary data to a ftp/http server that is sitting out there somewhere, have the phone(s) connect to that server and poll for new data periodically? I'm brand new to android development, basically all I want to do is grab this binary data from the device on my phone and parse/display it over google maps. How do any of those ideas sound, or is there a much easier way I am overlooking?
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Oct 6, 2010
I have created an android app. It sends a data message on a port for communicating with the same app on some other phone. While sending the message, i have encoded it into binary data using ISO8859_1 encoding.
byte[] b1=payload.getbytes();
I am able to receive the data message at the receiving end. But the problem is that after receving it in binary format , My app needs to decode the message back to string or human read-able format. But i am not able to do the same.
I have tried to convert it into String using 'toString()' but string contains binary character .
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Sep 8, 2010
My app will have an SQLite database with some embedded JPEG images -- basically the binary contents of a JPEG file stored as a Blob in the database. Can someone point me in the general direction of where to start to figure out how to convert this "array of bytes" into a Bitmap object that can be further manipulated and displayed in an ImageView?
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May 15, 2014
I primarily do hardware and firmware design, but a new product my company is developing has the need for an Android app and since I have the most Android programming experience (which is extremely limited) that leaves the task to me. I need a little guidance figuring out how to do a few things so that I can get this app up and running. I already have a simple GUI to display some stuff, but what I need is a way to handle data.
I am trying to receive a 148 byte stream of data over a serial connection, parse it into a structure and display certain values from that structure. The data is packed in a struct that is sent from a micro controller and due to that it has a very specific layout (i.e. the first 8 bytes mean this, the next 16 bytes are this... ). In C, I can just declare a struct with those values and use the #pragma pack function to eliminate any extra spacing the compiler would otherwise inject for alignment purposes, receive the data and do a memcpy into the struct to write the data. It's not the safest or cleanest way to do it, but it takes very little time and if you do CRC tests to make sure the data received is valid it works like a charm.
Now to the root of the problem: How do I declare structs in Java? Is there a way to pack them tightly like you can using C? Once I've received the binary data, is there a way to parse it into the structure easily? These are the issues we hardware programmers face when dealing with Java...
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Sep 22, 2011
I have an application that receives data in binary form through bluetooth. I read the data using bluetoothsocket to an byte[]. But i must parse all messages, because they must have an given format and they are in binary.
My solution was to convert byte[] to a string and then split the string and parse all received messages.
An example of the data to parse:
0000000010000001
I should know that the first 8 zeros are the header and 10000001 the real data.
My idea was to create a string that represents -> 0000000010000001 and then split the whole string in one byte and check the value, like:
string1 had 00000000
string2 had 10000001
I know that 8 zeros are the header, therefore string2 has the representation of the data.
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Jun 2, 2010
Hopefully i'm not asking anything obvious here.Basically I worked out that my HTC cable which came with my handset charges a lot quicker than the ebay ones I bought. I did some testing and initially I thought the spare 1000mA adaptor I bought was at fault. I only got about 6% charge per 30 mins. But then I tried the same adaptor with my HTC cable, and it gave me 15% in 30 mins.So I want to buy a spare cable, but I don't know how to tell the difference. Anyone able to explain, or direct me to a cable?
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Aug 4, 2010
Can anybody give me some clue that how to convert binary string into a string(english). I have tried and googled so much but couldn't find an answer.
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Oct 20, 2010
Does HTC sync compress images when syncing to the phone? Is there any sync applications / programs that compress?
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Jan 6, 2010
I have 2 questions.
Is there a way that to compress pictures for mms? When I had the Samsung moment it did it automatically.
2 I can't view some of my mms messages? It says download but it gives me an error.
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Dec 5, 2009
If I am going through my calendar day by day it shows me from about 8am to 5pm. If there's anything before 8am or after 5pm, I don't see it without scrolling. On my old Treo, it would get rid of some of the unallocated hours between 8am to 5pm to ensure other events fit on the screen. Anyway to do this within the Calendar? I'm using Agenda in the meantime but would really like to see just the day's events for whatever day I'm looking at.
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May 20, 2010
I think I need a step by step. So I ripped Avatar from a dvd using dvdfab. I chose main movie and Dvd9. This gave me a 7 gig file. I used handbrake to convert to mp4 at 480 x 272 or something on ipod legacy setting. When I put that file on the phone, it is 2 gigs. Does that seem too big? How can I compress this without a huge loss in quality? It plays perfect right now.
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Jun 14, 2010
Does Android have a native library that can make a jpeg from binary data from say, a json object?
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Aug 2, 2010
I am new to android and I want to read a binary file extension .AMF file.I really need your help this is really urgent.
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Aug 5, 2010
Can anybody please tell me how to get double and int value from a binary file. I have tried alot but its giving me wrong values.
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Feb 23, 2009
I am having problems downloading a binary file (video) in my app from the internet. In Quicktime, If I download it directly it works fine but through my app somehow it get's messed up (even though they look exactly the same in a text editor).
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May 19, 2009
Is there any way that i can add many words into main.dict currently used as Main Dictionary in Inputmethods package?? Please reply it's bit urgent.
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Mar 22, 2010
I met a big difficiult problem, i have researched more then 5 day's. Of course i read the LatinIME's algorithm for the suggestion.
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May 27, 2010
Android ndk is hard to use for the old autoconf based code, so i employed scratchbox2/emdebian to have a complete build environment. can i build a shared library in emdebian (arch is armel) and then use it in android?
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Mar 18, 2010
Is it possible to receive a binary SMS on a specific port?
I am currently receiving SMS via Action: "android.provider.Telephony.SMS_RECEIVED" from a BroadcastReceiver.
But i have no luck with binary SMS. I only get notified for text messages.
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May 20, 2010
How do I remove strings from / obfuscate a compiled binary? The goal is to avoid having people read the names of the functions/methods inside.
It is a dynamic library (.so) compiled from C++ code for Android with the NDK tools (includes GCC)
I compile with -O3 and already use arm-eabi-strip -g mylib.so to remove debugging symbols, but when I do strings mylib.so all the names of the functions/methods are still readable.
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Oct 21, 2012
I am in the need of the Info-zip unzip (and zip) binary for bash scripts, compiled for Android.The unzip included in busybox does not have the features that I need and the 7za and unrar binaries that I have do not have features needed also.
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Feb 18, 2010
I have 2 binary files that i would like to package with my apk. (/res/raw) i need to copy these 2 files to /sdcard when the application is run. how can i do this?
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Sep 2, 2010
I have a binary file which contains image. I have to jump on different locations in file to read the image file. So far I am using mark and reset methods but these are not helping me as I want. And I am using Input Stream to read the file.
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Aug 17, 2010
i have a map file which has several tile images in the form of binary data. now i have to jump my index to different location of the file and read that tile. but i could not find anything helpful for me i also checked mark() and skip() methods.but not helping me.is there any method or class which can do what exactly i want or any hint you want to give me.
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