use ocr to detect text in imported video file in swift

One way to use OCR to detect text in an imported video file in Swift is to capture frames from the video using AVFoundation, preprocess the frames to enhance text visibility, and then use Tesseract OCR engine to extract text from the frames. Here is a sample code:


main.swift
import AVFoundation
import TesseractOCR

// Create an AVAssetReader to read frames from video file
let url = Bundle.main.url(forResource: "video", withExtension: "mp4")!
let asset = AVAsset(url: url)
let reader = try! AVAssetReader(asset: asset)
let videoTrack = asset.tracks(withMediaType: .video)[0]
let outputSettings = [
    kCVPixelBufferPixelFormatTypeKey as String: NSNumber(value: kCVPixelFormatType_32BGRA)
] as [String: Any]
let readerOutput = AVAssetReaderTrackOutput(track: videoTrack, outputSettings: outputSettings)
reader.add(readerOutput)
reader.startReading()

// Create a Tesseract instance and set language
let tesseract = G8Tesseract(language: "eng")
tesseract?.engineMode = .tesseractCubeCombined
tesseract?.pageSegmentationMode = .auto
tesseract?.maximumRecognitionTime = 60.0

// Read frames and extract text
while let buffer = readerOutput.copyNextSampleBuffer() {
    // Convert CMSampleBuffer to UIImage
    let imageBuffer = CMSampleBufferGetImageBuffer(buffer)!
    CVPixelBufferLockBaseAddress(imageBuffer, .readOnly)
    let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)!
    let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer)
    let width = CVPixelBufferGetWidth(imageBuffer)
    let height = CVPixelBufferGetHeight(imageBuffer)
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.noneSkipFirst.rawValue | CGBitmapInfo.byteOrder32Little.rawValue)
    let context = CGContext(data: baseAddress, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)!
    let image = context.makeImage()!
    CVPixelBufferUnlockBaseAddress(imageBuffer, .readOnly)
    let uiImage = UIImage(cgImage: image)
    
    // Preprocess image to enhance text visibility
    let processedImage = preprocessImage(uiImage)
    
    // Extract text using Tesseract
    tesseract?.image = processedImage
    tesseract?.recognize()
    let recognizedText = tesseract?.recognizedText ?? ""
    print(recognizedText)
}
2068 chars
47 lines

In the above code, preprocessImage is a function that takes a UIImage and performs some image processing operations to highlight text in the image. This function can be implemented using various computer vision techniques, such as image thresholding, color transforms, edge detection, etc. The specific preprocessing steps depend on the characteristics of the input video file and the OCR engine being used.

Note that the above code assumes that the Tesseract OCR engine has been included in the project using a package manager or a framework import. Additionally, the AVFoundation and TesseractOCR frameworks need to be added to the Xcode project.

similar swift code snippets

detect text in imported video file in swift

how do i record record video with avassetwriter in swift

hello world in swift

protocol in swift

loop in swift

sort a list of people by name in swift

how do you determine if a string is a palindrome in swift

make a table view in swift

make http get request in swift

create an enum in swift

related categories