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• Changing x264 settings on the fly

  22 décembre 2018, par S Red

  I am curious to know if anyone has experience with modifying x264 settings during encoding (this is for testing live streaming hence I need to be able to modify settings based on cpu and upload characteristics).

  



  I saw an API for encoder_reconfig() in x264.h, curious if folks have used that, and if its accessible from ffmpeg ? Is it possible to modify a high-level option like 'preset', or do I need to modify individual options like chroma-me, trellis etc.

  


• FFmpeg drawtext filter error : "Cannot find a valid font for the family Sans"

  7 septembre 2024, par fatdrogen

  I'm trying to add text overlay to a video using FFmpeg's drawtext filter in my iOS app, but I'm encountering the following error :

  


  error : Cannot load default config file

  


  ERROR : Cannot find a valid font for the family Sans

  


  ERROR : Error initializing filter 'drawtext'

  


  ERROR : with args 'text=write some thing :'

  


  Here's the relevant part of my FFmpeg command :

  


  Copydrawtext=text='write some thing '

  


  Questions :

  


  What's causing this error, and how can I resolve it ?
Is there a way to specify a font that's guaranteed to be available on iOS devices ?
Are there any alternative approaches to adding text overlay in FFmpeg that might avoid this issue ?

  


  Environment :

  


  Platform : iOS
FFmpeg : Using MobileFFmpeg library
Swift

  


  Any help or guidance would be greatly appreciated !

  


  func makeGIFData(asset: AVAsset,  startTime: Double, endTime: Double, rotation: Double, overlayText: String) async throws -> Data {
    let fileName = "\(ProcessInfo.processInfo.globallyUniqueString)_input.mp4"
    let fileURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(fileName)
    
    // Export the asset to a temporary file
    guard let exporter = try? await AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetHighestQuality) else {
        throw NSError(domain: "GIFConversionError", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to create AVAssetExportSession"])
    }
    
    exporter.outputURL = fileURL
    exporter.outputFileType = .mp4
    exporter.timeRange = CMTimeRange(start: CMTime(seconds: startTime, preferredTimescale: 600), end: CMTime(seconds: endTime, preferredTimescale: 600))
    
    do {
        try await exporter.export()
    } catch {
        throw NSError(domain: "GIFConversionError", code: -2, userInfo: [NSLocalizedDescriptionKey: "Failed to export video: \(error.localizedDescription)"])
    }
    
    let outfileName = "\(ProcessInfo.processInfo.globallyUniqueString)_outfile.gif"
    let outfileURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(outfileName)
    
    // Get video dimensions
    guard let track = try? await asset.loadTracks(withMediaType: .video).first,
          let videoSize = try? await track.load(.naturalSize) else {
        throw NSError(domain: "GIFConversionError", code: -4, userInfo: [NSLocalizedDescriptionKey: "Failed to get video dimensions"])
    }
    
    // Prepare FFmpeg command
    var command = "-i \(fileURL.path) -vf "
    
    
    // Add text overlay
    let escapedText = overlayText.replacingOccurrences(of: ":", with: "\\:").replacingOccurrences(of: "'", with: "\\'")
    let fontColor = textColor.toHexString()
    
    // Use a more universally available font, or provide multiple options
    filters += ",drawtext=text='write some thing ':"
    
    // Add palette generation and application
    filters += ",split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse"
    
    // Add filters to command
    command += "\"\(filters)\""
    
    // Finalize command
    command += " -loop 0 \(outfileURL.path)"
    
    print("FFmpeg command: \(command)")
    
    let startTime = CFAbsoluteTimeGetCurrent()
    
    let result = MobileFFmpeg.execute(command)
    
    if result != RETURN_CODE_SUCCESS {
        throw NSError(domain: "GIFConversionError", code: Int(result), userInfo: [NSLocalizedDescriptionKey: "FFmpeg conversion failed"])
    }
    
    let timeElapsed = CFAbsoluteTimeGetCurrent() - startTime
    print("Time elapsed: \(timeElapsed) s.")
    
    // Read the generated GIF file
    guard let gifData = try? Data(contentsOf: outfileURL) else {
        throw NSError(domain: "GIFConversionError", code: -3, userInfo: [NSLocalizedDescriptionKey: "Failed to read generated GIF file"])
    }
    
    print("Animated GIF data created successfully. Size: \(gifData.count) bytes")
    
    // Clean up temporary files
    try? FileManager.default.removeItem(at: fileURL)
    try? FileManager.default.removeItem(at: outfileURL)
    
    return gifData
}
'''


  


• vulkan_decode : use the correct queue family for decoding ops

  14 août 2024, par Lynne

  vulkan_decode : use the correct queue family for decoding ops
  In 680d969a305c0927480573a1b455024088b51aeb, the new API was
  
  used to find a queue family for dispatch, but the found queue
  
  family was not used for decoding, just for dispatching.
  

  • [DH] libavcodec/vulkan_decode.c