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• FileNotFoundError on aws Lambda when concatenating videos with ffmpeg

  2 juillet 2021, par Shibu Menon

  Goal :

  



  

  • Concat 2 videos (both are in an s3 bucket) via aws Lambda using ffmpeg

  


  • Upload the resultant output.mp4 to another S3 bucket

  


  • Python 3+

  


  



  I've already created a layer containing a static ffmpeg

  



  The Error :

  



  {
  "errorMessage": "[Errno 2] No such file or directory: '/tmp/output.mp4'",
  "errorType": "FileNotFoundError",
  "stackTrace": [
    [
      "/var/task/lambda_function.py",
      19,
      "lambda_handler",
      "s3.Object(bucketLowRes, mp4OutputFileName).put(Body=open(new_file_key, 'rb'))"
    ]
  ]
}


  



  My Lambda function :

  



  import json
import os
import subprocess
import boto3

s3 = boto3.resource('s3')
bucketLowRes = s3.Bucket("bucket-conc-lowres")

def lambda_handler(event, context):
    # TODO implement

    mp4OutputFileName = 'output.mp4'

    new_file_key = os.path.abspath(os.path.join(os.sep, 'tmp', mp4OutputFileName))
    subprocess.call( ['/opt/ffmpeg', '-i', 'concat:s3://bucket-word-clips/00th76kqwfs915hbixycb77y9v3riwsj30.mp4|s3://bucket-word-clips/00uoakp6jyafbu13ycvl6w2i9tj42eux30.mp4', new_file_key ] )

    s3.Object(bucketLowRes, mp4OutputFileName).put(Body=open(new_file_key, 'rb'))

    return {
        'statusCode': 200,
        'body': json.dumps('Hello from Lambda!')
    }


  



  Question :

  



  

  • FileNotFoundError : Where is the output mp4 file of my ffmpeg concat being saved ??

  


  • And if it is being saved to /tmp/output.mp4 , then why the FileNotFoundError ??

  


  



  thanks

  


• Creating an Init file from existing non-fragmented, segmented MP4 files

  20 novembre 2018, par slhck

  I am performing chunked encodes of longer video files, where I’ve split the original file into individual sequences that I have encoded separately. These sequences are files of different length, depending on where the scene cuts appear—they may be between 2 and 5 seconds long. They all start with an I-frame and are standalone.

  My encoded sequences are all MP4s, e.g. :

  test_0000.mp4
  
  test_0001.mp4
  
  test_0002.mp4
  
  test_0003.mp4
  
  test_0004.mp4

  They all have common properties :

  $ mp4info test_0000.mp4
  
  
  
  File:
  
    major brand:      isom
  
    minor version:    200
  
    compatible brand: isom
  
    compatible brand: iso2
  
    compatible brand: mp41
  
    fast start:       no
  
  
  
  Movie:
  
    duration:   2016 ms
  
    time scale: 1000
  
    fragments:  no
  
  
  
  ...

  Now, in order to play those with a DASH player, I have to create an initialization segment and individual fragmented MP4s.

  I could generate the fragmented MP4s via mp4fragment which I run on each standalone MP4 file :

  $ mp4info test_0000.m4s
  
  File:
  
    major brand:      isom
  
    minor version:    200
  
    compatible brand: isom
  
    compatible brand: iso2
  
    compatible brand: mp41
  
    compatible brand: iso5
  
    fast start:       yes
  
  
  
  Movie:
  
    duration:   2016 ms
  
    time scale: 1000
  
    fragments:  yes
  
  
  
  ...

  But obviously, these are now not according to spec, and all contain a moov atom :

  

  What I’d need is individual media segments with only one moof and mdat box, which then require an initialization segment with only a moov box.

  How can I generate that from the existing, already encoded segments ?

  I know this appears like an XY problem. In principle, I could already segment my original file directly after encoding, and run those encodes at the same time, e.g. using ffmpeg’s dash muxer, or MP4Box, however :

  • There is almost no control over the resulting segment sizes, with respect to minimum and maximum duration
  • This approach does not parallelize

  I have also checked Bento4 ; it does not seem to offer this functionality. Neither does FFmpeg. MP4Box behaves similarly. They all assume you have one long file to start with.

  ---

  I see I could splice off the ftyp and moov boxes from these “fake fragments” in order to create an initialization segment. But I would end up with segments containing multiple moof and mdat boxes, which is not according to the specification – it only allows one fragment and media data box :

  4. Media Segments

  […] one optional Segment Type Box (styp) followed by a single Movie Fragment Box (moof) followed by one or more Media Data Boxes (mdat).

  I guess I can live with this the styp not being present.

• ffmpge command to merge file with good quality

  21 janvier 2016, par Hemant Kumar

  Hi I am looking for a better command that can merge both audio & video files into one with a better quality.

  I found this command from Muaz Khan’s WebRTC APIs.

  "ffmpeg -i {$audioFile} -i {$videoFile} -map 0:0 -map 1:0 {$mergedFileName}"

  Later on server i had to add "-strict -2" with this command as on server it says that above command is experimental if I still want to use it you should add "-strict -2" with it.

  It is working well but my video file (.webm) with size 2.2MB and audio file (.wav) with size 1.5MB was merged into a new file (.webm) with size 422.5KB. This new video file is having lag.

  Also I want the meta information for duration of video is already written on the resulting video file.

  Is there any command which can give the merged file without lagging and both video and audio of the new file are of good quality.