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• avformat/matroskaenc : Only write Cluster if it has in fact been opened

  2 mai 2020, par Andreas Rheinhardt

  avformat/matroskaenc : Only write Cluster if it has in fact been opened
  Since commit 4aa0665f393847c35387a1c673e62346d0acfc95, the dynamic
  
  buffer destined for the contents of the current Cluster is no longer
  
  constantly allocated, reallocated and then freed after writing the
  
  content ; instead it is reset and reused when closing a Cluster.
  Yet the code in mkv_write_trailer() still checked for whether a Cluster
  
  is open by checking whether the pointer to the dynamic buffer is NULL or
  
  not (instead of checking whether the position of the current Cluster is
  
   1 or not). If a Cluster was not open, an empty Cluster would be output.
  One usually does not run into this issue, because unless there are
  
  errors, there are only three possibilities to not have an opened Cluster
  
  at the end of writing a packet :
  
  The first is if one sent an audio packet to the muxer. It might trigger
  
  closing and outputting the old Cluster, but because the muxer caches
  
  audio packets internally, it would not be output immediately and
  
  therefore no new Cluster would be opened.
  
  The second is an audio packet that does not contain data (such packets
  
  are sometimes sent for side-data only, e.g. by the FLAC encoder). The
  
  only difference to the first scenario is that such packets are not
  
  cached.
  
  The third is if one explicitly flushes the muxer by sending a NULL
  
  packet via av_write_frame().
  If one also allows for errors, then there is also another possibility :
  
  Caching the audio packet may fail in the first scenario.
  If one calls av_write_trailer() after the first scenario, the cached
  
  audio packet will be output when writing the trailer, for which
  
  a Cluster is opened and everything is fine ; because flushing the muxer
  
  does currently not output the cached audio packet (if one is cached),
  
  the issue also does not exist if an audio packet has been cached before
  
  flushing. The issue only exists in one of the other scenarios.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskaenc.c

• avformat/matroskaenc : Make sure UIDs of delayed chapters are != 0

  27 avril 2020, par Andreas Rheinhardt

  avformat/matroskaenc : Make sure UIDs of delayed chapters are != 0
  This has previously only been checked if the chapters were initially
  
  available, but not if they were only written in the trailer.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskaenc.c

• Read S3 video file, process it with ffmpeg and upload to S3

  28 avril 2020, par Dario Rusignuolo

  I have a video stored in s3 bucket with authenticated-read ACL.

  



  I need to read and make a trailer with ffmpeg (nodejs)

  



  Here's the code I use to generate the trailer

  



  exports.generatePreview = (req, res) => {
    const getParams = {
        Bucket: S3_CREDENTIALS.bucketName,
        Key: req.params.key
    }
    s3.getSignedUrl('getObject', getParams, (err, signedRequest) => {
        console.log(signedRequest, err, 'getSignedUrl')
        ffmpeg(new URL(signedRequest))
            .size('640x?')
            .aspect('4:3')
        .seekInput('3:00')
        .duration('0:30')
        .then(function (video) {
            s3.putObject({ Bucket: S3_CREDENTIALS.bucketName, key: 'preview_' + req.body.key, Body: video }, function (err, data) {
                console.log(err, data)
            })
        });
});


  



  }

  



  Unfortunately, the constructor path seems not to read remote url. If I try to execute an ffmpeg command line with the same signedurl (i.e. ffmpeg -i "https://[bucketname].s3.eu-west-1.amazonaws.com/[key.mp4]?[signedParams]" -vn -acodec pcm_s16le -ar 44100 -ac 2 video.wav)

  



  The error I get is that the signedRequest url 'The input file does not exist'

  



  It seems fs.readFileSync https is not supported even if I try the request with http with the same result. fs.readFileSync(signedurl) => gives the same result

  



  How to overcome this issue ?