Ndtyjky

I have been at this for three days straight and it's driving me insane.

I have an event notification set up on an S3 bucket to field file.wav uploads, transcode them using a static ffmpeg binary hosted on an node.js AWS Lambda instance, then re-upload the file to the same bucket.

The issue I'm having - and this does work on my local XUbuntu machine - is that the file is read, encoded, and written synchronously, yet some sort of asynchronous access is distorting the audio file. A symptom of the distortion is static white noise, and previously (although it may have been fixed) there was overlapping audio.

This is the process:

1. File is uploaded via frontend


2. Lambda is invoked


3. Handler is entered and all necessary endpoint construction is performed

exports.handler = async (event, context, callback) => {

    callback();



    const buckinfo = event.Records[0].s3;

    const filename = buckinfo.object.key.toString().replace(/+/g, " ");

    var des = filename.split('/');

    var newFile = des[des.length - 1];



    console.log('filename : ', filename);

    const logKey = event.logKey || `${'logKey'}.log`;

    s3Bucket = event.s3Bucket || process.env.S3_UPLOADS;



    var meta = null;

    const inputFilename = tempy.file({extension: 'wav'});

    const temp3Filename = tempy.file({extension: 'mp3'});



    console.log('input file', inputFilename);

    console.log('output file', temp3Filename);



    var mp3Filename = filename.split('/');



    mp3Filename[4] = 'mp3';

    mp3Filename =   mp3Filename[0] + '/' +

                    mp3Filename[1] + '/' +

                    mp3Filename[2] + '/' +

                    mp3Filename[3] + '/' +

                    mp3Filename[4] + '/' +

                    newFile.split('.').slice(0, -1).join('.') + '.mp3';

    console.log('mp3Filename : ', mp3Filename);

    await readIn(filename, inputFilename, false);

    await encodeFile(inputFilename, temp3Filename, false);

    await writeOut(temp3Filename, mp3Filename, false);

};

(YES it's gross, but it works, so only worry about the last three lines)

4. The file is read in from the key passed to it via the upload event

async function readIn(inputFilename, transfer, local) {

    console.log('reading in locally?', local);

    console.log(`reading from ${inputFilename} to ${transfer}`);



    const writeStream = fs.createWriteStream(transfer);

    var file;



    local? await new Promise((resolve, revoke) => {

        file = fs.createReadStream(inputFilename);

        writeStream.on('finish', () => {

            console.log('file finished reading');

            resolve();

        });

        writeStream.on('error', (err) => {

            console.log('things messed up');

            revoke();

        });

        file.pipe(writeStream);

    }) : await new Promise((resolve, revoke) => {

        writeStream.on('finish', () => {

            console.log('file finished reading');

            resolve();

        });

        writeStream.on('error', (err) => {

            console.log('things messed up');

            revoke();

        });

        s3.getObject({

            Bucket  :s3Bucket,

            Key     :inputFilename

        }, function(err, data) {

            if (err) {

                console.log(err, err.stack);

            } else {

                console.log('data got!');

            }

        }).createReadStream().pipe(writeStream);

    });

    console.log('returning to main from reading');

    return ;

}

5. The file is then transcoded using the Linux x86-64 static binary

async function encodeFile(inputFilename, temp3Filename) {

    const ffmpeg = path.resolve(__dirname, 'ffmpeg');

    const ffmpegArgs = ['-i', inputFilename, '-vn', '-acodec', 'libmp3lame', temp3Filename];

    console.log('arguments to ffmpeg', ffmpegArgs);

    const ps = child_process.spawn(ffmpeg, ffmpegArgs);

    await new Promise((resolve, revoke) => {

        console.log('beginning encoding process');

        ps.stderr.on('data', (data) => {console.log(`stderr: ${data}`);});

        ps.on('exit', function(code, signal) {

            console.log('child process exited with ' + `code ${code} and signal ${signal}`);

        });

        ps.on('error', function(code, signal) {

            console.log('child process erred with ' + `code ${code} and signal ${signal}`);

        });

        ps.on('close', (code) => {

            if (code === 0) {

                resolve(code);

            } else {

                revoke(code);

            }

        });

    });

    console.log('returning to main from encoding');

    return ;

}

6. The temporary encoded file is then re-uploaded to the S3 bucket async

function writeOut(transfer, outFile, local) {

    console.log('writing out locally?', local);

    console.log(`writing to ${outFile} from ${transfer}`);



    const data = fs.createReadStream(transfer);



    local? await new Promise((resolve, revoke) => {

        const file = fs.createWriteStream(outFile);

        file.on('finish', () => {

            console.log('file finished writing');

            resolve();

        });

        file.on('error', (err) => {

            console.log('things messed up');

            revoke();

        });

        data.pipe(file);

    }) : await new Promise((resolve, revoke) => {

        const params = {

            Bucket: s3Bucket,

            Key: outFile,

            Body: data,

            ContentType: 'audio/mpeg'

        };

        const options = {

            partSize: 40 * 1024 * 1024,

            queueSize: 1

        };

        s3.upload(params, options, function(err, data) {

            if (err) {

                console.log('error uploading', err, err.stack);

                revoke(err);

            } else {

                console.log(data);

                resolve();

            }

        });

    });

    console.log('returning to main from writing');

}

Any tips or suggestions are more than welcome.
Here is the main() I use for local testing:

async function main(input, output) {

        const inputFilename = tempy.file({extension: 'wav'});

        const temp3Filename = tempy.file({extension: 'mp3'});

        await readIn(input, inputFilename, true);

        const logs = await encodeFile(inputFilename, temp3Filename, true);

        await writeOut(temp3Filename, output, true);

    }

main('../../../../../../Downloads/<file>.wav', './local.mp3');

You will need to uncomment the s3 modules require statements to get this to run. All you need are the node_modules required above and the static fmmpeg binary dependent on your OS.

Thanks!

S3 Logs:

START RequestId: eb6dfbc7-e927-11e8-9a7e-c172e5d12174 Version: $LATEST

2018-11-15T22:43:50.558Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    filename : <S3/endpoint.wav>

2018-11-15T22:43:50.573Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    input file /tmp/80e9f1a9539d322a6a9cfd429b78a2f3.wav

2018-11-15T22:43:50.573Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    output file /tmp/0e1119ad256b7bfa6f5cc270eaa273cc.mp3

2018-11-15T22:43:50.573Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    mp3Filename : <S3/endpoint.mp3>

2018-11-15T22:43:50.573Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    reading in locally? false

2018-11-15T22:43:50.573Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    reading from <S3/endpoint.wav> to /tmp/80e9f1a9539d322a6a9cfd429b78a2f3.wav

2018-11-15T22:43:53.073Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    data got!

2018-11-15T22:43:53.113Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    file finished reading

2018-11-15T22:43:53.113Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    returning to main from reading

2018-11-15T22:43:53.113Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    arguments to ffmpeg [ '-i',

'/tmp/80e9f1a9539d322a6a9cfd429b78a2f3.wav',

'-vn',

'-acodec',

'libmp3lame',

'/tmp/0e1119ad256b7bfa6f5cc270eaa273cc.mp3' ]

2018-11-15T22:43:53.153Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    beginning encoding process

2018-11-15T22:43:53.913Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: ffmpeg version 4.1-static https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2018 the FFmpeg developers

built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516

configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg



2018-11-15T22:43:53.972Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: libavutil 56. 22.100 / 56. 22.100

libavcodec 58. 35.100 / 58. 35.100

libavformat 58. 20.100 / 58. 20.100

libavdevice 58. 5.100 / 58. 5.100

libavfilter 7. 40.101 / 7. 40.101

libswscale 5. 3.100 / 5. 3.100

libswresample 3. 3.100 / 3. 3.100

libpostproc 55. 3.100 / 55. 3.100



2018-11-15T22:43:54.453Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: Guessed Channel Layout for Input Stream #0.0 : mono

Input #0, wav, from '/tmp/80e9f1a9539d322a6a9cfd429b78a2f3.wav':

Duration: 00:00:56.57, bitrate: 1059 kb/s

Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, mono, s16, 705 kb/s



2018-11-15T22:43:54.472Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: Stream mapping:

Stream #0:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))

Press [q] to stop, [?] for help



2018-11-15T22:43:54.612Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: Output #0, mp3, to '/tmp/0e1119ad256b7bfa6f5cc270eaa273cc.mp3':

Metadata:

TSSE : Lavf58.20.100



2018-11-15T22:43:54.612Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, mono, s16p

Metadata:

encoder : Lavc58.35.100 libmp3lame



2018-11-15T22:43:54.994Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 10kB time=00:00:01.25 bitrate= 66.7kbits/s speed=2.41x 

2018-11-15T22:43:55.494Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 26kB time=00:00:03.24 bitrate= 65.1kbits/s speed=3.17x 

2018-11-15T22:43:56.013Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 42kB time=00:00:05.33 bitrate= 64.6kbits/s speed=3.46x 

2018-11-15T22:43:56.514Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 59kB time=00:00:07.47 bitrate= 64.5kbits/s speed=3.66x 

2018-11-15T22:43:57.014Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 75kB time=00:00:09.56 bitrate= 64.4kbits/s speed=3.76x 

2018-11-15T22:43:57.515Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 91kB time=00:00:11.57 bitrate= 64.3kbits/s speed= 3.8x 

2018-11-15T22:43:58.034Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 105kB time=00:00:13.42 bitrate= 64.3kbits/s speed=3.77x 

2018-11-15T22:43:58.534Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 122kB time=00:00:15.51 bitrate= 64.2kbits/s speed=3.82x 

2018-11-15T22:43:59.035Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 138kB time=00:00:17.60 bitrate= 64.2kbits/s speed=3.86x 

2018-11-15T22:43:59.535Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 153kB time=00:00:19.54 bitrate= 64.2kbits/s speed=3.86x 

2018-11-15T22:44:00.054Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 169kB time=00:00:21.60 bitrate= 64.2kbits/s speed=3.87x 

2018-11-15T22:44:00.574Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 187kB time=00:00:23.87 bitrate= 64.1kbits/s speed=3.91x 

2018-11-15T22:44:01.093Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 204kB time=00:00:26.04 bitrate= 64.1kbits/s speed=3.93x 

2018-11-15T22:44:01.614Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 221kB time=00:00:28.23 bitrate= 64.1kbits/s speed=3.95x 

2018-11-15T22:44:02.114Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 236kB time=00:00:30.09 bitrate= 64.1kbits/s speed=3.94x 

2018-11-15T22:44:02.614Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 252kB time=00:00:32.26 bitrate= 64.1kbits/s speed=3.96x 

2018-11-15T22:44:03.152Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:34.40 bitrate= 61.0kbits/s speed=3.98x 

2018-11-15T22:44:03.653Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:36.54 bitrate= 57.4kbits/s speed= 4x 

2018-11-15T22:44:04.153Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:38.58 bitrate= 54.4kbits/s speed= 4x 

2018-11-15T22:44:04.634Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:40.59 bitrate= 51.7kbits/s speed= 4x 

2018-11-15T22:44:05.134Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:42.81 bitrate= 49.0kbits/s speed=4.02x 

2018-11-15T22:44:05.672Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:44.95 bitrate= 46.6kbits/s speed=4.03x 

2018-11-15T22:44:06.192Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:46.99 bitrate= 44.6kbits/s speed=4.02x 

2018-11-15T22:44:06.674Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:49.18 bitrate= 42.6kbits/s speed=4.03x 

2018-11-15T22:44:07.954Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:51.22 bitrate= 40.9kbits/s speed=4.03x 

size= 256kB time=00:00:53.36 bitrate= 39.3kbits/s speed=4.03x 

2018-11-15T22:44:08.214Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 256kB time=00:00:54.83 bitrate= 38.2kbits/s speed=3.99x 

2018-11-15T22:44:08.613Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    stderr: size= 442kB time=00:00:56.58 bitrate= 64.1kbits/s speed= 4x 

video:0kB audio:442kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.050126%



2018-11-15T22:44:08.713Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    child process exited with code 0 and signal null

2018-11-15T22:44:08.713Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    returning to main from encoding

2018-11-15T22:44:08.713Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    writing out locally? false

2018-11-15T22:44:08.713Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    writing to <S3/endpoint.mp3> from /tmp/0e1119ad256b7bfa6f5cc270eaa273cc.mp3

2018-11-15T22:44:09.045Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    { ETag: <ETag>,

Location: <S3/endpoint.mp3>,

key: <S3/endpoint.mp3>,

Key: <S3/endpoint.mp3>,

Bucket: <S3> }

2018-11-15T22:44:09.072Z    eb6dfbc7-e927-11e8-9a7e-c172e5d12174    returning to main from writing

END RequestId: eb6dfbc7-e927-11e8-9a7e-c172e5d12174

REPORT RequestId: eb6dfbc7-e927-11e8-9a7e-c172e5d12174  Duration: 18536.93 ms   Billed Duration: 18600 ms Memory Size: 192 MB   Max Memory Used: 107 MB

Here's a similar question from a user who reported something similar via Lambda with Python.

The accepted answer mentions a fix by explicitly ignoring STDIN for the subprocess. Perhaps you can try something similar with Node's child_process.spawn and options.stdio? Check out the child_process.spawn option docs for more info.

Also, have you seen this very comprehensive blog post Building a Media Transcoder with Exodus, FFmpeg, and AWS Lambda? That post covers a solution built with JS that might also be helpful in pointing you in the right direction.