FFmpegFrameRecorder recorder?.start() Hangs Indefinitely

I am experiencing an issue where FFmpegFrameRecorder.start() hangs indefinitely when trying to start an RTSP stream. The issue occurs consistently and prevents the stream from being established.

Steps to Reproduce:

Initialize FFmpegFrameRecorder with the following settings: kotlin Copy code val screenSize = Toolkit.getDefaultToolkit().screenSize val recorder = FFmpegFrameRecorder("rtsp://0.0.0.0:8556/live", screenSize.width, screenSize.height).apply { format = "rtsp" videoCodec = avcodec.AV_CODEC_ID_H264 audioCodec = avcodec.AV_CODEC_ID_AAC frameRate = 30.0 videoBitrate = 2000000 audioBitrate = 192000 interleaved = true maxDelay = 500000 option("rtsp_transport", "tcp") } Call recorder.start(). The call to recorder.start() hangs indefinitely. Expected Behavior: The recorder should start without hanging, allowing the RTSP stream to be established.

Environment:

JavaCV version: 1.5.6 FFmpeg version: 4.4-1.5.6 OS: [Your Operating System] JDK version: [Your JDK version] Additional Information: I have initialized the FFmpeg network components before starting the recorder. Here is the complete code used to reproduce the issue:

kotlin Copy code import org.bytedeco.ffmpeg.global.avcodec import org.bytedeco.ffmpeg.global.avformat import org.bytedeco.ffmpeg.global.avutil import org.bytedeco.javacpp.Loader import org.bytedeco.javacv.FFmpegFrameRecorder import org.bytedeco.javacv.Java2DFrameConverter import java.awt.Rectangle import java.awt.Robot import java.awt.Toolkit import java.awt.image.BufferedImage import javax.sound.sampled.* import kotlin.concurrent.thread import java.nio.ByteBuffer import java.nio.ShortBuffer

class JvmRtspServer {

private var recorder: FFmpegFrameRecorder? = null

fun start() {
    thread { 
        mainStartRtsp() 
    }

    // Delay to ensure RTSP server starts
    Thread.sleep(2000)

    // Initialize FFmpeg libraries
    try {
        Loader.load(avutil::class.java)
        Loader.load(avcodec::class.java)
        Loader.load(avformat::class.java)
        avformat.avformat_network_init()
        println("FFmpeg network initialized")
    } catch (e: Exception) {
        e.printStackTrace()
        return
    }

    // Initialize the recorder
    try {
        val screenSize = Toolkit.getDefaultToolkit().screenSize
        recorder = FFmpegFrameRecorder("rtsp://0.0.0.0:8556/live", screenSize.width, screenSize.height).apply {
            format = "rtsp"
            videoCodec = avcodec.AV_CODEC_ID_H264
            audioCodec = avcodec.AV_CODEC_ID_AAC
            frameRate = 30.0
            videoBitrate = 2000000
            audioBitrate = 192000
            interleaved = true
            maxDelay = 500000
            option("rtsp_transport", "tcp")
        }
        recorder?.start()
        println("FFmpegFrameRecorder started")
    } catch (e: Exception) {
        e.printStackTrace()
        return
    }

    // Delay to ensure the recorder starts
    Thread.sleep(1000)

    // Capture audio
    val audioLine = captureAudio()
    val audioFormat = audioLine.format
    val bufferSize = audioFormat.frameSize * audioFormat.sampleRate.toInt() * 2
    val audioBuffer = ByteArray(bufferSize)
    val converter = Java2DFrameConverter()

    // Capture and stream screen
    thread {
        while (true) {
            try {
                val image = captureScreen()
                if (image != null) {
                    val frame = converter.convert(image)
                    if (frame != null) {
                        recorder?.record(frame)
                        println("Frame recorded successfully")
                    } else {
                        println("Failed to convert image to frame")
                    }
                } else {
                    println("Failed to capture screen image")
                }
                Thread.sleep((1000 / recorder!!.frameRate).toLong())
            } catch (e: Exception) {
                e.printStackTrace()
            }
        }
    }

    // Capture and stream audio
    thread {
        while (true) {
            try {
                val bytesRead = audioLine.read(audioBuffer, 0, audioBuffer.size)
                if (bytesRead > 0) {
                    val audioSamples = ShortArray(bytesRead / 2) // 2 bytes per sample for 16-bit audio
                    ByteBuffer.wrap(audioBuffer).asShortBuffer().get(audioSamples)
                    val shortBuffer = ShortBuffer.wrap(audioSamples)
                    recorder?.recordSamples(audioFormat.sampleRate.toInt(), audioFormat.channels, shortBuffer)
                    println("Audio samples recorded successfully")
                }
            } catch (e: Exception) {
                e.printStackTrace()
            }
        }
    }
}

private fun captureScreen(): BufferedImage? {
    return try {
        val screenRect = Rectangle(Toolkit.getDefaultToolkit().screenSize)
        Robot().createScreenCapture(screenRect)
    } catch (e: Exception) {
        e.printStackTrace()
        null
    }
}

private fun captureAudio(): TargetDataLine {
    return try {
        val format = AudioFormat(44100.0f, 16, 2, true, false)
        val info = DataLine.Info(TargetDataLine::class.java, format)
        val line = AudioSystem.getLine(info) as TargetDataLine
        line.open(format)
        line.start()
        println("Audio line opened and started")
        line
    } catch (e: Exception) {
        e.printStackTrace()
        throw RuntimeException("Failed to capture audio")
    }
}

// Mock function to start RTSP server. Replace with actual implementation.
fun mainStartRtsp() {
    println("RTSP server started")
}

}

// Main function to create and start the RTSP server fun main() { val server = JvmRtspServer() server.start() } Logs:

arduino Copy code FFmpeg network initialized Audio line opened and started RTSP server started Additional Information:

This issue occurs even after ensuring FFmpeg network initialization. The same issue is reproducible on multiple machines with the same configuration. Screenshots/Video: (Attach any relevant screenshots or a video demonstrating the issue, if possible.)

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