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• Is there any way to change file FPS in javascript browser or prepare wav conventer to 60FPS videos ?

  16 novembre 2020, par SZtyro

  I'm making web application which stores short audio files that have been cut from large video files. User uploads .mp4 file, chooses sound length and here's a little trick. Cutting audio can only be done in backend (correct me if I'm wrong) and sending 700MB data is not good option, so I use code below to decode audio data from .mp4 and then I send it with start and stop params. Backend (Node.js) use's FFMPEG to cut audio and save's it.

  


  This part works, but i realised that decoded audio from 60FPS video doesn't sound good (not terrible but totally useless in my app). My goal is to avoid third party, especially desktop, apps (like audacity) and allow user to cut revelant part of audio from any mp4 video. Is there any way to convert 60FPS video to 30FPS video (ArrayBuffer) in browser and then decode audio ?

  


        fileInput.onchange = event => {
      this.file = event.target["files"][0];
      //.mp4 file
      this.fileURL = URL.createObjectURL(this.file)

      let baseAudioContext = new AudioContext();
      this.file.arrayBuffer().then(buff => {

        baseAudioContext.decodeAudioData(buff,
          success => {
            console.log(success)
            this.bufferToWave(success, 0, success.length);
          },
          err => console.log(err));
      })
    }

  bufferToWave(abuffer, offset, len) {

    var numOfChan = abuffer.numberOfChannels,
      length = len * numOfChan * 2 + 44,
      buffer = new ArrayBuffer(length),
      view = new DataView(buffer),
      channels = [], i, sample,
      pos = 0;

    // write WAVE header
    setUint32(0x46464952);                         // "RIFF"
    setUint32(length - 8);                         // file length - 8
    setUint32(0x45564157);                         // "WAVE"

    setUint32(0x20746d66);                         // "fmt " chunk
    setUint32(16);                                 // length = 16
    setUint16(1);                                  // PCM (uncompressed)
    setUint16(numOfChan);
    setUint32(abuffer.sampleRate);
    setUint32(abuffer.sampleRate * 2 * numOfChan); // avg. bytes/sec
    setUint16(numOfChan * 2);                      // block-align
    setUint16(16);                                 // 16-bit (hardcoded in this demo)

    setUint32(0x61746164);                         // "data" - chunk
    setUint32(length - pos - 4);                   // chunk length

    // write interleaved data
    for (i = 0; i < abuffer.numberOfChannels; i++)
      channels.push(abuffer.getChannelData(i));

    while (pos < length) {
      for (i = 0; i < numOfChan; i++) {             // interleave channels
        sample = Math.max(-1, Math.min(1, channels[i][offset])); // clamp
        sample = (0.5 + sample < 0 ? sample * 32768 : sample * 32767) | 0; // scale to 16-bit signed int
        view.setInt16(pos, sample, true);          // update data chunk
        pos += 2;
      }
      offset++                                     // next source sample
    }

    // create Blob
    //return (URL || webkitURL).createObjectURL(new Blob([buffer], { type: "audio/wav" }));
    var u = (URL || webkitURL).createObjectURL(new Blob([buffer], { type: "audio/wav" }));

    //temporary part
    //downloading file to check quality
    //in this part sound is already broken, no need to show backend code
    const a = document.createElement('a');
    a.style.display = 'none';
    a.href = u;
    a.download = name;
    document.body.appendChild(a);
    a.click();



    function setUint16(data) {
      view.setUint16(pos, data, true);
      pos += 2;
    }

    function setUint32(data) {
      view.setUint32(pos, data, true);
      pos += 4;
    }
  }


  


• Restreaming another nginx rtmp stream

  9 novembre 2019, par Amar Kalabić

  First of all, I’ll explain what I want to achieve, because there might be even better way to achieve this.
  I am looking at making 2 streams work, one is pushing to twitch.tv and youtube with delay and other one is live (without delay) that can be watched using VLC or whatever.

  I am able to achieve this partially, but "live" stream just breaks sometimes randomly with this error :

  Failed to update header with correct duration.
  
  Failed to update header with correct filesize.

  Before, I had "Could not find codec parameters" error, but I solved it by adding this to my ffmpeg command :

  -analyzeduration 2147483647 -probesize 2147483647

  What I’ve already done is :

  I made these rtmp server and apps in my nginx.conf

  rtmp {
  
  server {
  
      listen 1935;
  
      chunk_size 4096;
  
  
  
      application delay_live {
  
          live on;
  
          record off;
  
          push_reconnect 500ms;
  
  
  
          push rtmp://live-vie.twitch.tv/app/my_stream_key;
  
          push rtmp://a.rtmp.youtube.com/live2/my_stream_key;
  
  
  
      }
  
  
  
      application live {
  
                      live on;
  
                      record off;
  
              }
  
  
  
      application delay {
  
          live on;
  
          record all;
  
          record_path /tmp/nginx;
  
  
  
          # Work with timestamp to know when to continue streaming
  
          record_suffix .flv;
  
          record_unique on;
  
  
  
          # Work with signals to know when to continue streaming
  
          #record_append on;
  
  
  
          exec_publish sudo sh /home/start.sh;
  
      }
  
  
  
      exec_static mkdir /tmp/nginx;   #Working dir. Must be consistend with the delayer.py
  
      }
  
  }

  On exec_publish I run this .sh script :

  sudo screen -dmS delay bash -c "python /usr/local/nginx/sbin/delay/rtmp_stream_delayer.py; sleep 9999";
  
  sleep 0.5;
  
  sudo screen -dmS live bash -c "python /usr/local/nginx/sbin/live/rtmp_stream_live.py; sleep 9999";

  Those two python scripts are a little bit changed script from this git :

  https://github.com/sistason/rtmp_stream_delayer
  Few things I changed there is I used ffmpeg instead of avconv to call the commands, and inside rtmp_stream_live.py I’ve set the same directory/file as rtmp_stream_delayer.py (so it basically uses same .flv file to stream live). rtmp_stream_live.py has delay set to 0. Also I added -analyzeduration 2147483647 -probesize 2147483647 to my live stream ffmpeg call to avoid codec errors I previously had.

  Full ffmpeg calls that I use :

  rtmp_stream_delayer.py

  subprocess.check_output('ffmpeg -re -i {0} -codec copy -f flv {1}'.format(filename, "rtmp://my_ip:port/delay_live").split())

  rtmp_stream_live.py

  subprocess.check_output('ffmpeg -re -analyzeduration 2147483647 -probesize 2147483647 -i /tmp/nginx/{0} -codec copy -f {1}'.format(filename, STREAM_DESTINATION).split())

  I tried adding this ffmpeg flag, but it didn’t help at all (codec errors are back again) :

   flv -flvflags no_duration_filesize

  Delay stream works like a charm and without any problems, but live stream randomly stops with update header errors, I haven’t been able to trigger it myself, it just happens randomly !

  Thanks in advance !

• Command build failed ndk

  1er janvier 2021, par ALI RAZA

  I want to integrate ffmpeg lib in my android app . So i am using ndk ,but i am stuck on this issue,I dont know why the error is appearing ,Thanks in advance ;

  


  It is the gradle code that i am using in my app and also the ffmpeg-android-maker path is provided

  


  plugins {
id 'com.android.application'


  


  


  android 
compileSdkVersion 30
buildToolsVersion "30.0.3"

  


  defaultConfig {
    applicationId "com.reactive.myapplication"
    minSdkVersion 16
    targetSdkVersion 30
    versionCode 1
    versionName "1.0"

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    externalNativeBuild {
        cmake {
            cppFlags ""
        }
    }
}
flavorDimensions "market"
productFlavors {
    google {
        dimension "market"
        ndk {
            // Since the App Bundle is used, there is no problem in packaging all these ABIs
            abiFilters 'x86', 'x86_64', 'armeabi-v7a', 'arm64-v8a'
        }
    }
    amazon {
        dimension "market"
        applicationIdSuffix ".amzn"
        ndk {
            // Amazon Appstore doesn't support multiple APKs for non-Amazon devices.
            // There is no point in x86 support here, as the majority of devices with the
            // Amazon Appstore are ARM-based. And it seems to be a common practice for other
            // apps in this market.
            abiFilters 'armeabi-v7a'
        }
    }
    huawei {
        dimension "market"
        applicationIdSuffix ".huawei"
        ndk {
            // Huawei App Gallery supports App Bundle format
            abiFilters 'x86', 'x86_64', 'armeabi-v7a', 'arm64-v8a'
        }
    }
}
sourceSets {
    main {
        // let gradle pack the shared library into the apk
        jniLibs.srcDirs = ['../ffmpeg-android-maker/output/lib']
    }
}

bundle {
    language {
        enableSplit = true
    }
    density {
        enableSplit = true
    }
    abi {
        enableSplit = true
    }
}

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}
externalNativeBuild {
    cmake {
        path "src/main/cpp/CMakeLists.txt"
        version "3.10.2"
    }
}
compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8

    targetCompatibility JavaVersion.VERSION_1_8
}


  


  


  dependencies

  


  implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'com.google.android.material:material:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
testImplementation 'junit:junit:4.+'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'


  


  


  And It is cmake ,


  


  And this is error i am facing :
Build command failed.
Error while executing process /home/ali/Android/Sdk/cmake/3.10.2.4988404/bin/ninja with arguments -C /home/ali/AndroidStudioProjects/FfmpegApp/app/.cxx/cmake/amazonDebug/armeabi-v7a native-lib
ninja : Entering directory `/home/ali/AndroidStudioProjects/FfmpegApp/app/.cxx/cmake/amazonDebug/armeabi-v7a'

  


  ninja : error : '/home/ali/AndroidStudioProjects/FfmpegApp/app/src/main/ffmpeg-android-maker/output/lib/armeabi-v7a/libavutil.so', needed by '/home/ali/AndroidStudioProjects/FfmpegApp/app/build/intermediates/cmake/amazonDebug/obj/armeabi-v7a/libnative-lib.so', missing and no known rule to make it