jtrim - Developer IT

What is PTS in reference to video encoding?

- by jtrim

Could someone briefly explain what the acronym PTS means in reference to video encoding?

Apple documentation incorrect about MKMapView -regionThatFits: ?

In the Apple documentation for the -regionThatFits: method of the MKMapView, it says that this will return a new region centered on the same point as the region that's passed in, only with the regions bounds corrected for the iPhone screen aspect ratio. This seems to be incorrect in implementation...before the call to this method, my region shows up as: $5 = { center = { latitude = 37.322898864746094, longitude = -122.03209686279297 }, span = { latitudeDelta = 14.278411865234375, longitudeDelta = 1.5202401876449585 } } ..however, after the call to this method, I end up with: $6 = { center = { latitude = 36.973427342552824, longitude = -122.03209686279297 }, span = { latitudeDelta = 14.521333317196799, longitudeDelta = 14.0625 } } This is quite a big difference on the map - this translates to the distance between Cupertino, CA and Santa Cruz, CA. Anyone else experience this discrepancy?

Read the article

Trying to compile x264 and ffmpeg for iPhone - "missing required architecture arm in file"

- by jtrim

I'm trying to compile x264 for use in an iPhone application. I see there are instructions on how to compile ffmpeg for use on the platform here: http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2009-October/076618.html , but I can't seem to find anything this complete for compiling x264 on the iPhone. I've found this source tree: http://gitorious.org/x264-arm that seems to have support for the ARM platform. Here is my config line: ./configure --cross-prefix=/usr/bin/ --host=arm-apple-darwin10 --extra-cflags="-B /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.2.sdk/usr/lib/ -I /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.2.sdk/usr/lib/" ...and inside configure I'm using the gas-preprocessor script (first link above) as my assembler: gas-preprocessor.pl gcc When I start compiling, it chunks away for a little while, then it spits out these warnings and a huge list of undefined symbols: ld: warning: option -s is obsolete and being ignored ld: warning: -force_cpusubtype_ALL will become unsupported for ARM architectures ld: warning: in /usr/lib/crt1.o, missing required architecture arm in file ld: warning: in /usr/X11R6/lib/libX11.dylib, missing required architecture arm in file ld: warning: in /usr/lib/libm.dylib, missing required architecture arm in file ld: warning: in /usr/lib/libpthread.dylib, missing required architecture arm in file ld: warning: in /usr/lib/libgcc_s.1.dylib, missing required architecture arm in file ld: warning: in /usr/lib/libSystem.dylib, missing required architecture arm in file Undefined symbols: My guess would be that the problem has to do with the "missing required architecture arm in file" warning...any ideas?

Read the article

iPhone - Get a pointer to the data behind CGDataProvider?

- by jtrim

I'm trying to take a CGImage and copy its data into a buffer for later processing. The code below is what I have so far, but there's one thing I don't like about it - it's copying the image data twice. Once for CGDataProviderCopyData() and once for the :getBytes:length call on imgData. I haven't been able to find a way to copy the image data directly into my buffer and cut out the CGDataProviderCopyData() step, but there has to be a way...any pointers? (...pun ftw) NSData *imgData = (NSData *)(CGDataProviderCopyData(CGImageGetDataProvider(myCGImageRef))); CGImageRelease(myCGImageRef); // i've got a previously-defined pointer to an available buffer called "mybuff" [imgData getBytes:mybuff length:[imgData length]];

Read the article

Calling UIGetScreenImage() on manually-spawned thread prints "_NSAutoreleaseNoPool():" message to lo

- by jtrim

This is the body of the selector that is specified in NSThread +detachNewThreadSelector:(SEL)aSelector toTarget:(id)aTarget withObject:(id)anArgument NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; while (doIt) { if (doItForSure) { NSLog(@"checking"); doItForSure = NO; (void)gettimeofday(&start, NULL); /* do some stuff */ // the next line prints "_NSAutoreleaseNoPool():" message to the log CGImageRef screenImage = UIGetScreenImage(); /* do some other stuff */ (void)gettimeofday(&end, NULL); elapsed = ((double)(end.tv_sec) + (double)(end.tv_usec) / 1000000) - ((double)(start.tv_sec) + (double)(start.tv_usec) / 1000000); NSLog(@"Time elapsed: %e", elapsed); [pool drain]; } } [pool release]; Even with the autorelease pool present, I get this printed to the log when I call UIGetScreenImage(): 2010-05-03 11:39:04.588 ProjectName[763:5903] *** _NSAutoreleaseNoPool(): Object 0x15a2e0 of class NSCFNumber autoreleased with no pool in place - just leaking Has anyone else seen this with UIGetScreenImage() on a separate thread?

Read the article

Cocoa - does CGDataProviderCopyData() actually copy the bytes? Or just the pointer?

- by jtrim

I'm running that method in quick succession as fast as I can, and the faster the better, so obviously if CGDataProviderCopyData() is actually copying the data byte-for-byte, then I think there must be a faster way to directly access that data...it's just bytes in memory. Anyone know for sure if CGDataProviderCopyData() actually copies the data? Or does it just create a new pointer to the existing data?

Read the article

iPhone / Cocoa - Are NSThreads less efficient than POSIX threads, or is the diff negligable?

- by jtrim

I'm looking at putting together a high-performance multi-threaded iPhone app that's doing a couple of fairly high-intensity operations concurrently. Is the performance difference between NSThread and POSIX threading enough to care about here? If so, I would assume POSIX threads would be more efficient because it bypasses the obj-c overhead. Is this correct?

Read the article

iPhone - is there any way to look at the core data store for a live app?

- by jtrim

I've got a live app on the app store that's producing some strange results when the user upgrades versions that I can't reproduce in my dev environment. Does anyone know of a way to inspect the core data store of a live iPhone app?

Read the article

FFmpeg + iPhone - Interesting (incorrect?) video encoding results

- by jtrim

I'm encoding some video on the iPhone by running the png image data through swscale to get YUV420P data then encoding that frame using the MSMPEG4V1 codec. In the api docs, avcodec_encode_video should return the number of bytes used from the output buffer by that encode operation. There are 234,000 bytes going into the encoder, but the result returned by avcodec_encode_video is simply "4". The result is exactly the same over 24 frames. Something seems fishy here...any insight? Here's a pastebin link to the code: http://pastebin.com/ht94FWva (sorry for the link away from SO, I just didn't want to have the code duplicated in several places) EDIT: Also, I've set up a custom log callback for ffmpeg to use and I have the log level set to "Verbose" (libavutil/log.h), so libavcodec should be logging any goofs to the console, but avcodec is quiet throught he whole operation. (note: I did test to make sure my log callback was working)

Read the article

Xcode 3.2 iPhone dev - Can't download development application data anymore?

- by jtrim

In the organizer of Xcode 3.1.x I used to be able to download the application data for an app in development (not installed thru itunes). In Xcode 3.2 I don't see that option anywhere. Am I missing something?

Developer IT