UIImage setImage crash - ios

Question

I implemented a video player with ffmpeg. Each frame is decoded successfully and can be saved to a valid jpg file and can be show in UIImageView when running in emulator. However, the memory is unbounded growing when I run my app in emulator. Moreover, the app will crash after excuting p_diaplayNextFrame 2 times when running on device. If I comment self.imageView.image = frame;, memory is not leaked and app is not crashed in emulator or on device.
-(void)p_displayNextFrame
{
ZCVFrameSec *frameSec = [video getNextVideoFrameSec];
UIImage *frame = [frameSec toUIImage];
static int fi = 0;
NSAssert( [NSThread isMainThread], #"Fatal error: must be main thread" );
NSString *fileName = [Utilities documentsPath:[NSString stringWithFormat:#"image%06d.jpg",fi++]];
NSLog(#"p_displayNextFrame write image file: %#",fileName);
// frame is saved successfully as jpg, I can view it
[UIImageJPEGRepresentation(frame, 0.7) writeToFile:fileName atomically:YES];
// leak(but not crash) in emulator, crash on device
self.imageView.image = frame;
double delayInSeconds = 0.05;//1/30.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
[self p_displayNextFrame];
});
}
ZCVFrameSec's toUIImage
- (UIImage*) toUIImage
{
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
CFDataRef data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, [self.data bytes], self.width * self.height * 3,kCFAllocatorNull);
NSAssert( [self.data length] == self.width * self.height * 3,
#"Fatal error: data length:%d, width:%d, height:%d, mul3=%d",
[self.data length],
self.width, self.height, self.width * self.height * 3 );
CGDataProviderRef provider = CGDataProviderCreateWithCFData(data);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGImageRef cgImage = CGImageCreate(self.width,
self.height,
8,
24,
3 * self.width,
colorSpace,
bitmapInfo,
provider,
NULL,
NO,
kCGRenderingIntentDefault);
UIImage *image = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
CGColorSpaceRelease(colorSpace);
CGDataProviderRelease(provider);
CFRelease(data);
return image;
}
crash info:
vImage`__vConvert_RGB888toBGRA8888_block_invoke98:
0x2d72aeb0: push {r4, r5, r6, r7, lr}
0x2d72aeb2: add r7, sp, #0xc
0x2d72aeb4: push.w {r8, r10}
0x2d72aeb8: ldr r2, [r0, #0x14]
0x2d72aeba: ldr r2, [r2, #0x4]
0x2d72aebc: ldr r2, [r2, #0x10]
0x2d72aebe: cmp r2, #0x0
0x2d72aec0: beq.w 0x2d72b076 ; __vConvert_RGB888toBGRA8888_block_invoke98 + 454
0x2d72aec4: vldr d16, [pc, #440]
0x2d72aec8: vmov.i32 q10, #0xff000000
0x2d72aecc: lsl.w r9, r1, #0x3
0x2d72aed0: vldr d18, [pc, #436]
0x2d72aed4: mov.w r12, #0x0
0x2d72aed8: ldr.w r8, [r0, #24]
0x2d72aedc: add.w r5, r0, #0x1c
0x2d72aee0: add.w r6, r12, r9
0x2d72aee4: ldm r5, {r2, r4, r5}
0x2d72aee6: ldr r3, [r0, #0x28]
0x2d72aee8: ldr r1, [r0, #0x2c]
0x2d72aeea: mla r2, r2, r6, r8
0x2d72aeee: mla lr, r5, r6, r4
0x2d72aef2: mla r3, r1, r6, r3
0x2d72aef6: tst.w r3, #0xf
0x2d72aefa: bne 0x2d72af44 ; __vConvert_RGB888toBGRA8888_block_invoke98 + 148
0x2d72aefc: tst.w r2, #0xf
0x2d72af00: bne 0x2d72af80 ; __vConvert_RGB888toBGRA8888_block_invoke98 + 208
0x2d72af02: ldr r4, [r0, #0x30]
0x2d72af04: movs r1, #0x0
0x2d72af06: tst.w lr, #0xf
0x2d72af0a: bne 0x2d72afbc ; __vConvert_RGB888toBGRA8888_block_invoke98 + 268
0x2d72af0c: cmp r4, #0x10
0x2d72af0e: blo 0x2d72aff2 ; __vConvert_RGB888toBGRA8888_block_invoke98 + 322
0x2d72af10: ldr r4, [r0, #0x34]
0x2d72af12: vld3.8 {d0, d2, d4}, [r2]!
Thread 1: EXC_BAD_ACCESS (code=1,address=0x7403000)
Any hint is appreciated!!!

Answer 1

I think the problem was because ZCVFrameSec *frameSec got deallocate after it got out of scope of -(void)p_displayNextFrame method.
If you used CFDataCreateWithBytesNoCopy on the bytes array in frameSec, then the byte array might vanish with frameSec before you finished using it in your cgImage, or you could say, in your UIImage *frame. This caused a EXC_BAD_ACCESS exception.
That why changing to CFDataCreate instead of CFDataCreateWithBytesNoCopy worked.
To answer your next question, how you can avoid copying a frame, I think there are a lot of ways to do that. You may hold your frameSec all the time until you change imageView to the next frame then you can release it.
To do that you can only declare a property to hold the current frame. Like this :
-(void)p_displayNextFrame
{
ZCVFrameSec *frameSec = [video getNextVideoFrameSec];
UIImage *frame = [frameSec toUIImage];
static int fi = 0;
NSAssert( [NSThread isMainThread], #"Fatal error: must be main thread" );
NSString *fileName = [Utilities documentsPath:[NSString stringWithFormat:#"image%06d.jpg",fi++]];
NSLog(#"p_displayNextFrame write image file: %#",fileName);
// frame is saved successfully as jpg, I can view it
[UIImageJPEGRepresentation(frame, 0.7) writeToFile:fileName atomically:YES];
// leak(but not crash) in emulator, crash on device
self.imageView.image = frame;
// At your header you should declare : #property ZCVFrameSec *currentFrameSec;
self.currentFrameSec = frameSec;
double delayInSeconds = 0.05;//1/30.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
[self p_displayNextFrame];
});
}