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• Convert mediarecorder blobs to a type that google speech to text can transcribe

  5 janvier 2021, par Manesha Ramesh

  I am making an app where the user browser records the user speaking and sends it to the server which then passes it on to the Google speech to the text interface. I am using mediaRecorder to get 1-second blobs which are sent to a server. On the server-side, I send these blobs over to the Google speech to the text interface. However, I am getting an empty transcriptions.

  



  I know what the issue is. Mediarecorder's default Mime Type id audio/WebM codec=opus, which is not accepted by google's speech to text API. After doing some research, I realize I need to use ffmpeg to convert blobs to LInear16. However, ffmpeg only accepts audio FILES and I want to be able to convert BLOBS. Then I can send the resulting converted blobs over to the API interface.

  



  server.js

  



  wsserver.on('connection', socket => {
    console.log("Listening on port 3002")
    audio = {
        content: null
    }
  socket.on('message',function(message){
        // const buffer = new Int16Array(message, 0, Math.floor(data.byteLength / 2));
        // console.log(`received from a client: ${new Uint8Array(message)}`);
        // console.log(message);
        audio.content = message.toString('base64')
        console.log(audio.content);
        livetranscriber.createRequest(audio).then(request => {
            livetranscriber.recognizeStream(request);
        });


  });
});


  



  livetranscriber

  



  module.exports = {
    createRequest: function(audio){
        const encoding = 'LINEAR16';
const sampleRateHertz = 16000;
const languageCode = 'en-US';
        return new Promise((resolve, reject, err) =>{
            if (err){
                reject(err)
            }
            else{
                const request = {
                    audio: audio,
                    config: {
                      encoding: encoding,
                      sampleRateHertz: sampleRateHertz,
                      languageCode: languageCode,
                    },
                    interimResults: false, // If you want interim results, set this to true
                  };
                  resolve(request);
            }
        });

    },
    recognizeStream: async function(request){
        const [response] = await client.recognize(request)
        const transcription = response.results
            .map(result => result.alternatives[0].transcript)
            .join('\n');
        console.log(`Transcription: ${transcription}`);
        // console.log(message);
        // message.pipe(recognizeStream);
    },

}


  



  client

  



   recorder.ondataavailable = function(e) {
            console.log('Data', e.data);

            var ws = new WebSocket('ws://localhost:3002/websocket');
            ws.onopen = function() {
              console.log("opening connection");

              // const stream = websocketStream(ws)
              // const duplex = WebSocket.createWebSocketStream(ws, { encoding: 'utf8' });
              var blob = new Blob(e, { 'type' : 'audio/wav; base64' });
              ws.send(blob.data);
              // e.data).pipe(stream); 
              // console.log(e.data);
              console.log("Sent the message")
            };

            // chunks.push(e.data);
            // socket.emit('data', e.data);
        }


  


• PyAV : force new framerate while remuxing stream ?

  7 juin 2019, par ToxicFrog

  I have a Python program that receives a sequence of H264 video frames over the network, which I want to display and, optionally, record. The camera records at 30FPS and sends frames as fast as it can, which isn’t consistently 30FPS due to changing network conditions ; sometimes it falls behind and then catches up, and rarely it drops frames entirely.

  The "display" part is easy ; I don’t need to care about timing or stream metadata, just display the frames as fast as they arrive :

  input = av.open(get_video_stream())
  
  for packet in input.demux(video=0):
  
    for frame in packet.decode():
  
      # A bunch of numpy and pygame code here to convert the frame to RGB
  
      # row-major and blit it to the screen

  The "record" part looks like it should be easy :

  input = av.open(get_video_stream())
  
  output = av.open(filename, 'w')
  
  output.add_stream(template=input.streams[0])
  
  for packet in input.demux(video=0):
  
    for frame in packet.decode():
  
      # ...display code...
  
    packet.stream = output.streams[0]
  
    output.mux_one(packet)
  
  output.close()

  And indeed this produces a valid MP4 file containing all the frames, and if I play it back with mplayer -fps 30 it works fine. But that -fps 30 is absolutely required :

  $ ffprobe output.mp4
  
  Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 960x720,
  
                    1277664 kb/s, 12800 fps, 12800 tbr, 12800 tbn, 25600 tbc (default)

  Note that 12,800 frames/second. It should look something like this (produced by calling mencoder -fps 30 and piping the frames into it) :

  $ ffprobe mencoder_test.mp4
  
  Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 960x720,
  
                    2998 kb/s, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)

  Inspecting the packets and frames I get from the input stream, I see :

  stream: time_base=1/1200000
  
  codec: framerate=25 time_base=1/50
  
  packet: dts=None pts=None duration=48000 time_base=1/1200000
  
  frame: dst=None pts=None time=None time_base=1/1200000

  So, the packets and frames don’t have timestamps at all ; they have a time_base which doesn’t match either the timebase that ends up in the final file or the actual framerate of the camera ; the codec has a framrate and timebase that doesn’t match the final file, the camera framerate, or the other video stream metadata !

  The PyAV documentation is all but entirely absent when it comes to issues of timing and framerate, but I have tried manually setting various combinations of stream, packet, and frame time_base, dts, and pts with no success. I can always remux the recorded videos again to get the correct framerate, but I’d rather write video files that are correct in the first place.

  So, how do I get pyAV to remux the video in a way that produces an output that is correctly marked as 30fps ?

• AWS Lambda failed to resolve hostname in child_process spawn

  6 septembre, par warly

  i'm trying to get ffmpeg working in AWS Lambda reading from and writing to S3. I crawled through dozens of aws documentations, stackoverflow questions and blog posts. All do it slightly different, but in the end none of them worked for me. So I hope to find help here :)
I sticked to the tutorial from InPlainEnglish : https://plainenglish.io/community/automated-video-processing-with-aws-lambda-and-ffmpeg-2834b7

  


  The ffprobe command does work, so ffmpeg is callable. But when calling ffmpeg within a child_process.spawn command i get the error Failed to resolve hostname my-bucket.s3.eu-central-1.amazonaws.com: System error

  


  export const handler = async (event) => {
    const s3 = new S3Client({});
    const bucket = event.Records[0].s3.bucket.name;
    const sourceKey = event.Records[0].s3.object.key;
    const sourceURL = await getSignedUrl(s3, new GetObjectCommand({
        Bucket: bucket,
        Key: sourceKey,
    }), {
        expiresIn: 900,
    });

    const tmpFilePath = 'tmp/video.mp4';
    const { convertOut } = await commander(`/opt/ffmpeg -i "${sourceURL}" -vf scale=1080:-2,format=yuv420p ${tmpFilePath}`);

    return {
        statusCode: 200,
        body: {
            result: JSON.stringify(convertOut),
        },
    };
};


  


  the signed url is fine. I've tested it with vanilla js await fetch(sourceURL) and it returned the file. The problem is that for some reason the child_process has no internet access.

  


  if anyone is able to point me in the right direction i would appreciate it :D

  


  Full error message :

  


  {
  "errorType": "Error",
  "errorMessage": "Command failed: /opt/ffmpeg -i \"https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject\" -vf scale=1080:-2,crop=1080:1350,format=yuv420p tmp/video.mp4\nffmpeg version 6.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2023 the FFmpeg developers\n  built with gcc 8 (Debian 8.3.0-6)\n  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzimg\n  libavutil      58. 29.100 / 58. 29.100\n  libavcodec     60. 31.102 / 60. 31.102\n  libavformat    60. 16.100 / 60. 16.100\n  libavdevice    60.  3.100 / 60.  3.100\n  libavfilter     9. 12.100 /  9. 12.100\n  libswscale      7.  5.100 /  7.  5.100\n  libswresample   4. 12.100 /  4. 12.100\n  libpostproc    57.  3.100 / 57.  3.100\n[tcp @ 0x141950d0] Failed to resolve hostname my-bucket.s3.eu-central-1.amazonaws.com: System error\n[in#0 @ 0x14190900] Error opening input: Input/output error\nError opening input file https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject.\nError opening input files: Input/output error\n",
  "trace": [
    "Error: Command failed: /opt/ffmpeg -i \"https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject\" -vf scale=1080:-2,crop=1080:1350,format=yuv420p tmp/video.mp4",
    "ffmpeg version 6.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2023 the FFmpeg developers",
    "  built with gcc 8 (Debian 8.3.0-6)",
    "  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzimg",
    "  libavutil      58. 29.100 / 58. 29.100",
    "  libavcodec     60. 31.102 / 60. 31.102",
    "  libavformat    60. 16.100 / 60. 16.100",
    "  libavdevice    60.  3.100 / 60.  3.100",
    "  libavfilter     9. 12.100 /  9. 12.100",
    "  libswscale      7.  5.100 /  7.  5.100",
    "  libswresample   4. 12.100 /  4. 12.100",
    "  libpostproc    57.  3.100 / 57.  3.100",
    "[tcp @ 0x141950d0] Failed to resolve hostname my-bucket.s3.eu-central-1.amazonaws.com: System error",
    "[in#0 @ 0x14190900] Error opening input: Input/output error",
    "Error opening input file https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject.",
    "Error opening input files: Input/output error",
    "",
    "    at ChildProcess.exithandler (node:child_process:422:12)",
    "    at ChildProcess.emit (node:events:518:28)",
    "    at maybeClose (node:internal/child_process:1105:16)",
    "    at ChildProcess._handle.onexit (node:internal/child_process:305:5)"
  ]
}


  


  Update : Turns out it is not S3 or internet, but the child_process which does not seem to have internet access. I've update my description above.