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• Why failes ffmpeg with "Failed to inject frame into filter network: Internal bug, should not have happened"?

  17 October 2023, by StackOverRigge

  I want to convert a MP4 video file into an animated gif file using ffmpeg. I am trying to do this in two steps:

  


  

  1. Create a palette image

  


  2. Convert the MP4 with the help of the palette image to a GIF file

  


  


  I'm using ffmpeg 6.0 essentials_build.

  


  First, I create a palette image:

  


  ffmpeg -v warning -i video.mp4 -vf "fps=15,scale=1366:768:flags=lanczos,palettegen=stats_mode=diff" -y palette.png


  


  Then, I'm trying to convert the MP4 to GIF:

  


  ffmpeg -i video.mp4 -i palette.png -lavfi "fps=15,scale=1366:768:flags=lanczos,paletteuse=dither=bayer:bayer_scale=5:diff_mode=rectangle" -y video.gif


  


  This command ends in this error message:

  


  Error while filtering: Internal bug, should not have happeneditrate=4279.9kbits/s speed=0.742x
Failed to inject frame into filter network: Internal bug, should not have happened
Error while processing the decoded data for stream #0:0


  


• Fix "Non-monotonic DTS" Warning Caused By asetnsamples Filter

  3 September 2024, by Harry Muscle

  I'm using the following complex filter to mute certain parts of an audio file and replace those parts with a beep generated by the sine filter:

  


  [0]asetnsamples=n=1,volume=0:enable='between(t,1.57,1.97)+between(t,4.77,5.27)+between(t,5.37,5.87)+between(t,6.37,6.77)'[dippedVocals];sine=d=10:f=1000:samples_per_frame=1,pan=stereo|FL=c0|FR=c0[constantBleep];[constantBleep]atrim=start=0:end=6.77[shortenedBleep];[shortenedBleep]volume=0:enable='between(t,0,1.57)+between(t,1.97,4.77)+between(t,5.27,5.37)+between(t,5.87,6.37)'[dippedBleep];[dippedVocals][dippedBleep]amix=inputs=2


  


  Since I need the locations specified to be exact I'm using the asetnsamples filter to set 1 sample per frame to get the highest possible accuracy. However, as soon as I add this asetnsamples filter to my filter chain I get thousands of these messages:

  


  Non-monotonic DTS; previous: XXX, current: XXX; changing to XXX.  This may result in incorrect timestamps in the output file.


  


  Any idea what's causing that and how to fix it? BTW, the input file is a ogg file encoded at 44100Hz and the output file is a wav file. Do wav files even contain timestamps?

  


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

  7 September 2024, by 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
}
'''