# CMSampleBufferRef from frameAvailable has wrong PresentationTime on only MacOS

**URL:** <https://forum.deepar.ai/t/cmsamplebufferref-from-frameavailable-has-wrong-presentationtime-on-only-macos/333>\
**Category:** SDK\
**Tags:** effect-help\
**Created:** [June 8, 2023, 5:48am UTC](https://forum.deepar.ai/t/cmsamplebufferref-from-frameavailable-has-wrong-presentationtime-on-only-macos/333 "2023-06-08T05:48:12Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![user5](https://dub1.discourse-cdn.com/flex017/user_avatar/forum.deepar.ai/user5/32/487_2.png) [@user5](https://forum.deepar.ai/u/user5)\
**Post date:** [June 8, 2023, 5:48am UTC](https://forum.deepar.ai/t/cmsamplebufferref-from-frameavailable-has-wrong-presentationtime-on-only-macos/333/1 "2023-06-08T05:48:12Z")

</div>

Hello. @jelena @Zak

Im facing issue that CMSampleBufferRef from frameAvailable has wrong PresentationTime on only MacOS.

It works fine on iOS

I call processFrame 15 times per 1 sec (15fps camera frame)  
it will have 0.06xxx gap time.

#if TARGET\_OS\_IPHONE  
//iOS  
[\_deepAR processFrame:pixelBufferRef mirror:NO];  
#else  
//Mac  
[\_deepAR processFrame:pixelBufferRef mirror:NO orientation:0];  
#endif

and then called frameAvailable

- (void)frameAvailable:(CMSampleBufferRef)sampleBuffer  
{  
Float64 time = CMTimeGetSeconds(CMSampleBufferGetPresentationTimeStamp(sampleBuffer));  
NSLog(@“daniel time %f”, time);  
}

in case of iOS,  
timestamp is uniformly incremented by 0.06xx.

2023-06-08 14:24:10.025495+0900 VoxTester[1268:133552] daniel time 73241.717466  
2023-06-08 14:24:10.096120+0900 VoxTester[1268:133552] daniel time 73241.785093  
2023-06-08 14:24:10.161399+0900 VoxTester[1268:133552] daniel time 73241.851839  
2023-06-08 14:24:10.226390+0900 VoxTester[1268:133552] daniel time 73241.917760  
2023-06-08 14:24:10.296743+0900 VoxTester[1268:133552] daniel time 73241.985169  
2023-06-08 14:24:10.361463+0900 VoxTester[1268:133552] daniel time 73242.051850  
2023-06-08 14:24:10.430925+0900 VoxTester[1268:133552] daniel time 73242.118535  
2023-06-08 14:24:10.497525+0900 VoxTester[1268:133552] daniel time 73242.185068  
2023-06-08 14:24:10.562688+0900 VoxTester[1268:133552] daniel time 73242.251562  
2023-06-08 14:24:10.628559+0900 VoxTester[1268:133552] daniel time 73242.318308  
2023-06-08 14:24:10.694348+0900 VoxTester[1268:133552] daniel time 73242.384630  
2023-06-08 14:24:10.760604+0900 VoxTester[1268:133552] daniel time 73242.451096  
2023-06-08 14:24:10.830081+0900 VoxTester[1268:133552] daniel time 73242.518417  
2023-06-08 14:24:10.894480+0900 VoxTester[1268:133552] daniel time 73242.584962  
2023-06-08 14:24:10.963515+0900 VoxTester[1268:133552] daniel time 73242.651509

but macOS case  
timestamp is uniformly incremented by 0.00006xxxx. it’s very small gap

2023-06-08 14:25:41.053736+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941040  
2023-06-08 14:25:41.129664+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941107  
2023-06-08 14:25:41.186480+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941175  
2023-06-08 14:25:41.265192+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941238  
2023-06-08 14:25:41.319194+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941306  
2023-06-08 14:25:41.391354+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941373  
2023-06-08 14:25:41.448202+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941437  
2023-06-08 14:25:41.517733+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941507  
2023-06-08 14:25:41.581989+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941572  
2023-06-08 14:25:41.653803+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941642  
2023-06-08 14:25:41.715090+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941703  
2023-06-08 14:25:41.785293+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941772  
2023-06-08 14:25:41.850129+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941838  
2023-06-08 14:25:41.915822+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941904  
2023-06-08 14:25:41.983228+0900 VoxTesterMOS[13162:16477957] daniel time 1686201.941972

please let me know why presentation gap is very small only macos