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• FFMPEG audio not delaying properly

  1 April 2022, by Spartan 117

  I am trying to mix two audio files together, with one audio being delayed. Here are the file details

  


  Audio 1 - https://pastebin.com/vkYsH88e, "startTime": "03/23/2022 21:20:27", "endTime": "03/24/2022 01:06:11"

  


  Audio 2 - https://pastebin.com/Gs4V96GQ, "startTime": "03/24/2022 01:05:30", "endTime": "03/24/2022 04:21:41"

  


  As you can see from the paste bin and the json property, Audio two starts about 3 hours and 45 minutes after Audio one, here is how i am trying to mix them

  


  ffmpeg -i RTb295d0534191e1acb22a45bb971a12e6.mka -i RT103bfe5f4b129860f69cd8e820f3a10b.mka -filter_complex "[1:a]adelay=13500s:all=1[apad]; [0:a][apad]amix=inputs=2:weights=1|1[aout]" -map [aout] combined_audio.mka


  


  Here is the output of that mixture - https://pastebin.com/KAsw0905

  


  Files have been uploaded here, if anyone wants to test - https://easyupload.io/m/xveng4

  


  The issue i'm having? Based on the parameters provided, the 2nd audio file should start playing after 3 hours and 45 minutes. Instead, it plays after 5 hours and 45 minutes. I'm new to FFMPEG and have been having trouble figuring this out. Any ideas?

  


• How to send libmmpeg AVPacket through WebRTC (using libdatachannel)

  29 March 2022, by mike

  I'm encoding a video frame with the ffmpeg libraries, generating an AVPacket with compressed data.

  


  Thanks to some recent advice here on S/O, I am trying to send that frame over a network using the WebRTC library libdatachannel, specifically by adapting the example here:

  


  https://github.com/paullouisageneau/libdatachannel/tree/master/examples/streamer

  


  I am seeing problems inside h264rtppacketizer.cpp (part of the library, not the example) which are almost certainly to do with how I'm providing the sample data.
(I don't think that this is anything to do with libdatachannel specifically, it will be an issue with what I'm sending)

  


  The example code reads each encoded frame from a file, and populates a sample by setting the content of the file to the contents of the file:

  


  sample = *reinterpret_cast *>(&fileContents);

  


  sample is just a std::vector<byte>;</byte>

  


  I have naively copied the contents of an AVPacket->data pointer into the sample vector:

  


  sample.resize(pkt->size);
memcpy(sample.data(), pkt->data, pkt->size * sizeof(std::byte));    


  


  but the packetizer is falling over when trying to get length values out of that data.
Specifically, in the following code, the first iteration gets a length of 1, but the second, looking up index 5, gives 1119887324. This is way too big for my data, which is only 3526 bytes (the whole frame is a single colour so likely to be small once encoded):

  


  while (index &lt; message->size()) {&#xA;assert(index &#x2B; 4 &lt; message->size());&#xA;auto lengthPtr = (uint32_t *)(message->data() &#x2B; index);&#xA;uint32_t length = ntohl(*lengthPtr);&#xA;auto naluStartIndex = index &#x2B; 4;&#xA;auto naluEndIndex = naluStartIndex &#x2B; length;&#xA;assert(naluEndIndex &lt;= message->size());    &#xA;        &#xA;auto begin = message->begin() &#x2B; naluStartIndex;&#xA;auto end = message->begin() &#x2B; naluEndIndex;&#xA;nalus->push_back(std::make_shared<nalunit>(begin, end));&#xA;index = naluEndIndex;&#xA;}&#xA;</nalunit>

  


  Here is a dump of

  


  uint32_t length = ntohl(*lengthPtr);


  


  for the first few elements of the message (*lengthPtr in parentheses):

  


  [2022-03-29 15:12:01.182] [info] index 0: 1  (16777216)
[2022-03-29 15:12:01.183] [info] index 1: 359  (1728118784)
[2022-03-29 15:12:01.184] [info] index 2: 91970  (1114046720)
[2022-03-29 15:12:01.186] [info] index 3: 23544512  (3225577217)
[2022-03-29 15:12:01.186] [info] index 4: 1732427807  (532693607)
[2022-03-29 15:12:01.187] [info] index 5: 1119887324  (3693068354)
[2022-03-29 15:12:01.188] [info] index 6: 3223313413  (98312128)
[2022-03-29 15:12:01.188] [info] index 7: 534512896  (384031)
[2022-03-29 15:12:01.188] [info] index 8: 3691315291  (1526728156)
[2022-03-29 15:12:01.189] [info] index 9: 83909537  (2707095557)
[2022-03-29 15:12:01.189] [info] index 10: 6004992  (10574592)
[2022-03-29 15:12:01.190] [info] index 11: 1537277952  (41307)
[2022-03-29 15:12:01.190] [info] index 12: 2701131779  (50331809)
[2022-03-29 15:12:01.192] [info] index 13: 768  (196608)


  


  (I know I should post a complete sample, I am working on it)

  


  


  • I am fairly sure I am just missing something basic. E.g. am I supposed to do something with the AVPacket side_data, does AVPacket have or miss some header info?

    


  


  • If I just fwrite the pkt->data for a single frame to disk, I can read the codec information with ffprobe:

    


  


  


  Input #0, h264, from 'encodedOut.h264':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: h264 (Constrained Baseline), yuv420p(progressive), 1280x720, 30 tbr, 1200k tbn


  


  

  • whereas the same for the example input files (again a single frame) gives the following:

  


  


  [h264 @ 000001c88d1135c0] Format h264 detected only with low score of 1, misdetection possible!
[h264 @ 000001c88f337400] missing picture in access unit with size 85306
[extract_extradata @ 000001c88d11ee40] No start code is found.
sample-0.h264: Invalid data found when processing input


  


• Stream image from Android with FFMPEG

  9 February 2023, by xnok

  I'm currently receiving images from an external source as byte array and I would like to send it as raw video format via ffmpeg to a stream URL, where I have a RTSP server that receives RTSP streams (a similar unanswered question). However, I haven't worked with FFMPEG in Java, so i can't find an example on how to do it. I have a callback that copies the image bytes to a byte array as follows:

  


          public class MainActivity extends Activity {
            final String rtmp_url = "rtmp://192.168.0.12:1935/live/test";
            private int PREVIEW_WIDTH = 384;
            private int PREVIEW_HEIGHT = 292;
            private String TAG = "MainActivity";
            String ffmpeg = Loader.load(org.bytedeco.ffmpeg.ffmpeg.class);
            final String command[] = {ffmpeg,
                            "-y",  //Add "-re" for simulated readtime streaming.
                            "-f", "rawvideo",
                            "-vcodec", "rawvideo",
                            "-pix_fmt", "bgr24",
                            "-s", (Integer.toString(PREVIEW_WIDTH) + "x" + Integer.toString(PREVIEW_HEIGHT)),
                            "-r", "10",
                            "-i", "pipe:",
                            "-c:v", "libx264",
                            "-pix_fmt", "yuv420p",
                            "-preset", "ultrafast",
                            "-f", "flv",
                            rtmp_url};
            
      private UVCCamera mUVCCamera;

public void handleStartPreview(Object surface) throws InterruptedException, IOException {
    Log.e(TAG, "handleStartPreview:mUVCCamera" + mUVCCamera + " mIsPreviewing:");
    if ((mUVCCamera == null)) return;
    Log.e(TAG, "handleStartPreview2 ");
    try {
        mUVCCamera.setPreviewSize(mWidth, mHeight, 1, 26, 0, UVCCamera.DEFAULT_BANDWIDTH, 0);
        Log.e(TAG, "handleStartPreview3 mWidth: " + mWidth + "mHeight:" + mHeight);
    } catch (IllegalArgumentException e) {
        try {
            // fallback to YUV mode
            mUVCCamera.setPreviewSize(mWidth, mHeight, 1, 26, UVCCamera.DEFAULT_PREVIEW_MODE, UVCCamera.DEFAULT_BANDWIDTH, 0);
            Log.e(TAG, "handleStartPreview4");
        } catch (IllegalArgumentException e1) {
            callOnError(e1);
            return;
        }
    }
    Log.e(TAG, "handleStartPreview: startPreview1");
    int result = mUVCCamera.startPreview();
    mUVCCamera.setFrameCallback(mIFrameCallback, UVCCamera.PIXEL_FORMAT_RGBX);
    mUVCCamera.startCapture();
    Toast.makeText(MainActivity.this,"Camera Started",Toast.LENGTH_SHORT).show();
    ProcessBuilder pb = new ProcessBuilder(command);
    pb.redirectErrorStream(true);
    Process process = pb.start();
    BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
    OutputStream writer = process.getOutputStream();
    byte img[] = new byte[192*108*3];
    for (int i = 0; i < 10; i++)
    {
        for (int y = 0; y < 108; y++)
        {
            for (int x = 0; x < 192; x++)
            {
                byte r = (byte)((x * y + i) % 255);
                byte g = (byte)((x * y + i*10) % 255);
                byte b = (byte)((x * y + i*20) % 255);
                img[(y*192 + x)*3] = b;
                img[(y*192 + x)*3+1] = g;
                img[(y*192 + x)*3+2] = r;
            }
        }

        writer.write(img);
    }

    writer.close();
    String line;
    while ((line = reader.readLine()) != null)
    {
        System.out.println(line);
    }

    process.waitFor();
}
public static void buildRawFrame(Mat img, int i)
{
    int p = img.cols() / 60;
    img.setTo(new Scalar(60, 60, 60));
    String text = Integer.toString(i+1);
    int font = Imgproc.FONT_HERSHEY_SIMPLEX;
    Point pos = new Point(img.cols()/2-p*10*(text.length()), img.rows()/2+p*10);
    Imgproc.putText(img, text, pos, font, p, new Scalar(255, 30, 30), p*2);  //Blue number
}


  


  Additionally: Android Camera Capture using FFmpeg

  


  uses ffmpeg to capture frame by frame from native android camera and instead of pushing it via RTMP, they used to generate a video file as output. Although how the image was passed via ffmpeg was not informed.

  


  frameData is my byte array and I'd like to know how can I write the necessary ffmpeg commands using ProcessBuilder to send an image via RTSP using ffmpeg for a given URL.

  


  An example of what I am trying to do, In Python 3 I could easily do it by doing:

  


  import cv2
import numpy as np
import socket
import sys
import pickle
import struct
import subprocess

fps = 25
width = 224
height = 224
rtmp_url = 'rtmp://192.168.0.13:1935/live/test'
    
    
    
    command = ['ffmpeg',
               '-y',
               '-f', 'rawvideo',
               '-vcodec', 'rawvideo',
               '-pix_fmt', 'bgr24',
               '-s', "{}x{}".format(width, height),
               '-r', str(fps),
               '-i', '-',
               '-c:v', 'libx264',
               '-pix_fmt', 'yuv420p',
               '-preset', 'ultrafast',
               '-f', 'flv',
               rtmp_url]
    
    p = subprocess.Popen(command, stdin=subprocess.PIPE)
    
    while(True):
        frame = np.random.randint([255], size=(224, 224, 3))
        frame = frame.astype(np.uint8)
        p.stdin.write(frame.tobytes())


  


  I would like to do the same thing in Android

  


  Update: I can reproduce @Rotem 's answer on Netbeans although, in Android I am getting NullPointer exception error when trying to execute pb.start().

  


      Process: com.infiRay.XthermMini, PID: 32089
    java.lang.NullPointerException
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:1012)
        at com.infiRay.XthermMini.MainActivity.handleStartPreview(MainActivity.java:512)
        at com.infiRay.XthermMini.MainActivity.startPreview(MainActivity.java:563)
        at com.infiRay.XthermMini.MainActivity.access$1000(MainActivity.java:49)
        at com.infiRay.XthermMini.MainActivity$3.onConnect(MainActivity.java:316)
        at com.serenegiant.usb.USBMonitor$3.run(USBMonitor.java:620)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loopOnce(Looper.java:226)
        at android.os.Looper.loop(Looper.java:313)
        at android.os.HandlerThread.run(HandlerThread.java:67)
2022-06-02 11:47:20.300 32089-1049/com.infiRay.XthermMini E/libUVCCamera: [1049*UVCPreviewIR.cpp:505:uvc_preview_frame_callback]:receive err data
2022-06-02 11:47:20.304 32089-1049/com.infiRay.XthermMini E/libUVCCamera: [1049*UVCPreviewIR.cpp:505:uvc_preview_frame_callback]:receive err data
2022-06-02 11:47:20.304 32089-1049/com.infiRay.XthermMini E/libUVCCamera: [1049*UVCPreviewIR.cpp:505:uvc_preview_frame_callback]:receive err data
2022-06-02 11:47:20.308 32089-1049/com.infiRay.XthermMini E/libUVCCamera: [1049*UVCPreviewIR.cpp:505:uvc_preview_frame_callback]:receive err data
2022-06-02 11:47:20.312 32089-32089/com.infiRay.XthermMini E/MainActivity: onPause:
2022-06-02 11:47:20.314 32089-32581/com.infiRay.XthermMini I/Process: Sending signal. PID: 32089 SIG: 9