[android-beginners] Re: Poor performance on my file loader (code optimization help!)
Thanks to everyone for the help on this. As I mentioned, I'm rather
new to Java, so things like StringTokenizer being legacy are news.
Believe it or not the file format uses actual frames instead of
keyframes (hence no timestamp or other indication of time or frames
between each being parsed out), but this is all still up in the air.
Obviously it's a very amateur way to do it right now. I'll probably
shift back to quaternions and worry about interpolating later (it
might be a application size vs. performance vs. memory usage thing in
the end. I'm not sure). Thanks for the links.
The LineNumberReader was actually hijacked from some open source code
intended for a very similar purpose. I didn't know what to use for
this scenario and so finding someone else using LNR meant I jumped on
it as the ideal solution. Safe to say I'll be trying R.E.s and/or
buffered reader soon enough. Are mark and reset really that taxing?
More so than basically buffering the several lines that might need to
be re-parsed?
Thanks again. Very helpful.
Glen
On Sep 24, 10:14 am, Kaj Bjurman kaj.bjur...@gmail.com wrote:
Is there a reason to why you use a LineNumberReader? I would instead
use a BufferedReader, that will probably improve your performance.
I don't know anything about the dataformat in the file, but there
probably is a much faster way to parse it than using all those
StringTokenizers (or regexp even if that might be faster). I would
also try to parse the file without mark and reset.
On 20 Sep, 20:28, Glen Kimsey gkim...@gmail.com wrote:
Hello!
I'm fairly new to both Android and Java (pretty experienced in C/C++),
and (stupidly, perhaps) took on a big project. In it, I need to load
information about 3D models and their respective animations from a
text file (proprietary file format based on PSK/PSA).
The loading process on a sample (1000+ line) file is abysmally slow
(more than 4 minutes). The good news is that there are lots and lots
of ways I can improve it. What I'm hoping to find out here is if
there's anything in *particular* in my code that is very inefficient
that I can change. Don't worry about offending me, I know this is
amateur code here.
Some possible causes for the slowness:
- Extensive use of parseFloat()
- Creating new StringTokenizer for every line
- Inefficiencies in for() loops (not caching as necessary?)
- Repeated use of the acos() and sqrt() functions
I'd like to find out from you gentlemen (ladies) what you think is the
major thing eating up my time here. If there's some tool I can use to
find out what lines of code are taking up the most time that'd be
ideal. I'm open to any possible solutions. The file format can
change (and probably will). I could even do something as drastic as
performing this load in a separate app (before distribution) and
somehow exporting the resulting object (KdfAnimation) that could more
easily be picked back up (this would work in C, but I'm doubtful Java
would allow such low-level memory copying).
One final note is that the action loading section of this code
occupies about 3/4 of the files being loaded (so this section may be
more important to optimize).
Loader Code
public class KdfLoader {
public static KdfAnimation load(String file) throws IOException {
KdfAnimation anim = new KdfAnimation();
FileInputStream fis = new FileInputStream(file);
String line = [start];
LineNumberReader lnr = new LineNumberReader(new
InputStreamReader
(fis));
int boneNum = 0;
try {
for (line = lnr.readLine(); line != null; line =
lnr.readLine()) {
if (line.length() 0) {
if (line.startsWith(numbones)) {
// Ignore it for now
}
else if (line.startsWith(bone)) {
// Bone define
StringTokenizer tok = new
StringTokenizer(line);
KdfBone bone = new KdfBone();
// Toss out bone
tok.nextToken();
// Set name
bone.boneName = tok.nextToken();
if (boneNum == 0) {
// Root bone. Ignore
children and parent id in file
bone.parentId = 0;
bone.parent = null;
// ignore numchildren x
// ignore parentid x
[android-beginners] Re: Poor performance on my file loader (code optimization help!)
Thanks for the reply. I think your suggestion of going binary is one
of the better ones I had considered. Especially because I can avoid
the parseFloat() calls altogether using this method.
As for the quaternion vs axis/angle, I had thought I HAD to translate
them originally (I found out later with more research that I just had
to use the more complicated matrix math rather than simple glrotate
and gltranslate calls if I didn't). I don't suppose you could direct
me to a tutorial or good description that will help a 3D rendering
newbie like me use the quaternions? If it really is better/faster, I
want to go that route rather than finding out later I should have.
I'm still looking for any additional suggestions on what particular
parts of the code might be killing my load times, although I'm sure
switching to binary and not using acos and sqrt will help quite a bit.
Thanks,
Glen
On Sep 22, 5:03 am, a1 arco...@gmail.com wrote:
On 20 Wrz, 20:28, Glen Kimsey gkim...@gmail.com wrote:
Hello!
I'm fairly new to both Android and Java (pretty experienced in C/C++),
and (stupidly, perhaps) took on a big project. In it, I need to load
information about 3D models and their respective animations from a
text file (proprietary file format based on PSK/PSA).
cut
private static float[] parseRotLine(String line) {
float[] retFloat = new float[4];
StringTokenizer tok = new StringTokenizer(line);
// Ignore rot
tok.nextToken();
// theta
tok.nextToken();
retFloat[0] = wToTheta(Float.parseFloat(tok.nextToken()));
// x
tok.nextToken();
retFloat[1] = Float.parseFloat(tok.nextToken());
// y
tok.nextToken();
retFloat[2] = Float.parseFloat(tok.nextToken());
// z
tok.nextToken();
retFloat[3] = Float.parseFloat(tok.nextToken());
// Need to scale this vector to make glRotate happy
retFloat = scaleAxisAngleVector(retFloat);
return retFloat;
}
private static float wToTheta(float w) {
// w = cos(theta/2)
float theta = (float)Math.acos((double)w) * 2;
// convert theta to degrees
theta = 180 * theta / (float)Math.PI;
// The above calculation only gave us a value from 0 to 180
because
of arccosine
// TODO: Determine if this is a problem. Note that w can be
negative, and this implies 180 degrees
if (w 0) {
theta += 180;
}
return theta;
}
private static float[] scaleAxisAngleVector(float[] unscaled) {
float[] scaled = new float[4];
// scale = sqrt(x^2 + y^2 + z^2);
float scale = (float)Math.sqrt(unscaled[1] * unscaled[1] +
unscaled
[2] * unscaled[2] + unscaled[3] * unscaled[3]);
if (scale != 0) {
scaled[0] = unscaled[0];
scaled[1] = unscaled[1] / scale;
scaled[2] = unscaled[2] / scale;
scaled[3] = unscaled[3] / scale;
}
else
{
// Scale can be 0, which means we're not rotating
// but dividing by zero is bad, and glRotate still
// needs a normalized vector.
scaled[0] = 0;
scaled[1] = 1;
scaled[2] = 0;
scaled[3] = 0;
}
return scaled;
}}
End of Loader Code
Ugh, why oh why are you transforming quaterninions to axis/angle
representation? Quaternion interpolation is easier, and gives better
result (you will also save a lot of time on calculations).
About performance, if it's possible (eg. you are not downloading the
scene files from network or smth), write a small utility that will
convert text file to binary representation offline, and then read the
binary files on android. Also try to minimize number of allocation
during file loading.
--
Bart 'arcone1' janusz
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[android-beginners] Re: Poor performance on my file loader (code optimization help!)
Fadden, Sorry, I missed your reply when I responded to Bart! I tried to find significant ways that I could avoid allocation, but the StringTokenizer is the main thing that I'm calling 'new' on and I didn't see any way to avoid doing that for every line. Your suggestion of using regexs for a parser kind of threw me off, because I didn't even see that as a possibility. I'll have to look into that and see what you mean. I also didn't know the G1 didn't have floating- point hardware. Will this likely be the case for other android phones in the near future? This information combined with Bart's suggestion to stick with quaternions means I'll very likely be removing those calls to acos and sqrt entirely. Also, thanks for the links. Your reply was extremely helpful. Thanks! Glen On Sep 21, 7:22 pm, fadden fad...@android.com wrote: On Sep 20, 11:28 am, Glen Kimsey gkim...@gmail.com wrote: The loading process on a sample (1000+ line) file is abysmally slow (more than 4 minutes). [...] Some possible causes for the slowness: - Extensive use of parseFloat() - Creating new StringTokenizer for every line - Inefficiencies in for() loops (not caching as necessary?) - Repeated use of the acos() and sqrt() functions Re-use objects when possible to avoid allocation and construction overhead. For a parser using regular expressions, you avoid the cost of recompiling the RE. acos() and sqrt() are not especially fast; sqrt () in particular, since the G1 lacks floating-point hardware. You can get some sense for where the time is going with the method tracing facility: http://developer.android.com/guide/developing/tools/traceview.html [...] I could even do something as drastic as performing this load in a separate app (before distribution) and somehow exporting the resulting object (KdfAnimation) that could more easily be picked back up (this would work in C, but I'm doubtful Java would allow such low-level memory copying). Java does provide a serialization mechanism, but it's not widely loved. :-) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Android Beginners group. To post to this group, send email to android-beginners@googlegroups.com To unsubscribe from this group, send email to android-beginners-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-beginners?hl=en -~--~~~~--~~--~--~---
[android-beginners] Poor performance on my file loader (code optimization help!)
Hello!
I'm fairly new to both Android and Java (pretty experienced in C/C++),
and (stupidly, perhaps) took on a big project. In it, I need to load
information about 3D models and their respective animations from a
text file (proprietary file format based on PSK/PSA).
The loading process on a sample (1000+ line) file is abysmally slow
(more than 4 minutes). The good news is that there are lots and lots
of ways I can improve it. What I'm hoping to find out here is if
there's anything in *particular* in my code that is very inefficient
that I can change. Don't worry about offending me, I know this is
amateur code here.
Some possible causes for the slowness:
- Extensive use of parseFloat()
- Creating new StringTokenizer for every line
- Inefficiencies in for() loops (not caching as necessary?)
- Repeated use of the acos() and sqrt() functions
I'd like to find out from you gentlemen (ladies) what you think is the
major thing eating up my time here. If there's some tool I can use to
find out what lines of code are taking up the most time that'd be
ideal. I'm open to any possible solutions. The file format can
change (and probably will). I could even do something as drastic as
performing this load in a separate app (before distribution) and
somehow exporting the resulting object (KdfAnimation) that could more
easily be picked back up (this would work in C, but I'm doubtful Java
would allow such low-level memory copying).
One final note is that the action loading section of this code
occupies about 3/4 of the files being loaded (so this section may be
more important to optimize).
Loader Code
public class KdfLoader {
public static KdfAnimation load(String file) throws IOException {
KdfAnimation anim = new KdfAnimation();
FileInputStream fis = new FileInputStream(file);
String line = [start];
LineNumberReader lnr = new LineNumberReader(new
InputStreamReader
(fis));
int boneNum = 0;
try {
for (line = lnr.readLine(); line != null; line =
lnr.readLine()) {
if (line.length() 0) {
if (line.startsWith(numbones)) {
// Ignore it for now
}
else if (line.startsWith(bone)) {
// Bone define
StringTokenizer tok = new
StringTokenizer(line);
KdfBone bone = new KdfBone();
// Toss out bone
tok.nextToken();
// Set name
bone.boneName = tok.nextToken();
if (boneNum == 0) {
// Root bone. Ignore children
and parent id in file
bone.parentId = 0;
bone.parent = null;
// ignore numchildren x
// ignore parentid x
}
else
{
// ignore numchildren x
tok.nextToken();
tok.nextToken();
// ignore parentid text
tok.nextToken();
bone.parentId =
Integer.parseInt(tok.nextToken());
bone.parent =
anim.allBones.get(bone.parentId);
}
// get loc and rot
line = lnr.readLine();
bone.loc = parseLocLine(line);
line = lnr.readLine();
bone.rot = parseRotLine(line);
// Handle explicit linkage
while(true) {
lnr.mark(1000);
line = lnr.readLine();
if (line.startsWith(obj)) {
tok = new
StringTokenizer(line);
// ignore obj
tok.nextToken();
bone.partLinks.add(tok.nextToken());
[android-beginners] Re: Is it possible from Android device to access a local pc?
The standard way to do real-time audio over a network connection is using RTP (real time protocol), which is what Voice Over IP is based on. While there are almost certainly RTP libraries available in Java, I'm not sure Android will let you get straight PCM data from the microphone or send PCM data straight to the speaker/headphones. That's your main question, Kevin. In Linux you would do this using ALSA. I'm pretty sure Android will let you wrap the PCM data (or unwrap it) into RTP and send it along (if not you could fake it over HTTP, but it'd be messy), but the other end requires low level hardware access. Two sort of answer both of your questions, if you can get that close to the hardware you'll most likely need root access which means it wouldn't be a normal Android Market app. On Sep 21, 12:19 am, kevin j ken...@verizon.net wrote: I'm interested in something similar. I would like to know if the following application is possible given the currently available tools and OS services. I want to send audio from the microphone in real-time over Wi-Fi to a Windows desktop application. I also want to send data which represents what screen icons have been tapped. I want to receive audio and data the same way - using Wi-Fi. Sincerely, Kevin J On Jul 23, 8:47 am, Sean Hodges seanhodge...@googlemail.com wrote: Android supports bluetooth,Wifi(local networking) and USB. Which one you want will depend on your requirements. For easy sychronisation of files between phone and PC, USB is probably a good choice; assuming you don't require the connection to be wireless. Regards, Sean On Thu, Jul 23, 2009 at 2:37 PM, Michael Leungmichaelchi...@gmail.com wrote: Hi all, I am new to Android. I am thinking to build an application for my personal use. It has a desktop version and I will build a simple Android client. Without using Internet, Is it possible from Android device to access a local pc? so I can do a sync with data between two versions? -- Regards, Michael Leung http://www.itblogs.info http://www.michaelleung.info-Hide quoted text - - Show quoted text - --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Android Beginners group. To post to this group, send email to android-beginners@googlegroups.com To unsubscribe from this group, send email to android-beginners-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-beginners?hl=en -~--~~~~--~~--~--~---
