GPU Image : Best resolution with Higher FPS

Question

I am using GPU framework, to record videos.

@property (nonatomic, strong) GPUImageStillCamera *stillCamera;

I am setting this property which changes Resolution and FPS.

self.stillCamera.captureSession.sessionPreset = AVCaptureSessionPresetHigh;

On iPhone6, 6+ and iPhone5s I am getting 1920*1080 with 30fps.

For iPod5th generation and iPhone5, I need 24fps with 1920*1080 resolution, same as Native camera app. But I am Only getting 8-9FPS with 1920*1080 resolution.

I have tried value AVCaptureSessionPreset1920x1080 as well.

I have also tried,

[self.stillCamera.inputCamera lockForConfiguration:nil];

self.stillCamera.inputCamera.activeVideoMinFrameDuration = CMTimeMake(1, 24);
self.stillCamera.inputCamera.activeVideoMaxFrameDuration = CMTimeMake(1, 24);
[self.stillCamera.inputCamera unlockForConfiguration];

but this not affecting when I am using self.stillCamera.captureSession.sessionPreset = AVCaptureSessionPresetHigh;

I have also tried,

[self.stillCamera setFrameRate:24];

this is also not working with self.stillCamera.captureSession.sessionPreset = AVCaptureSessionPresetHigh;

I have also tried this function [self configureCameraForHighestFrameRate:self.stillCamera.inputCamera];as well, from apple documentation https://developer.apple.com/library/mac/documentation/AVFoundation/Reference/AVCaptureDevice_Class/index.html but I am only getting FPS near 18, with 1280*720 resolution,

I need 1920*1080 with 24fps, on iPod5th and iPhone5. Please help me.

You help will be appriciated. Thanks in advance.