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• lavd/v4l2 : detect device name truncation

  25 novembre 2021, par Anton Khirnov

  lavd/v4l2 : detect device name truncation
  Silences the following warning with gcc 10 :
  
  src/libavdevice/v4l2.c : In function ‘v4l2_get_device_list’ :
  
  src/libavdevice/v4l2.c:1042:64 : warning : ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size 251 [-Wformat-truncation=]
  
   1042 |         ret = snprintf(device_name, sizeof(device_name), "/dev/%s", entry->d_name) ;
  
        |                                                                ^ 
  
  src/libavdevice/v4l2.c:1042:15 : note : ‘snprintf’ output between 6 and 261 bytes into a destination of size 256
  
   1042 |         ret = snprintf(device_name, sizeof(device_name), "/dev/%s", entry->d_name) ;
  
        |               ^ 
  Previous patches intending to silence it have proposed increasing the
  
  buffer size, but doing that correctly seems to be tricky. Failing on
  
  truncation is simpler and just as effective (as excessively long device
  
  names are unlikely).
  

  • [DH] libavdevice/v4l2.c

• ffmpeg node js s3 stream screenshots qestion

  20 octobre 2015, par user3564443

  On my Node js server I need get video from s3, generate thumbnail for it, set thumbnail to s3, without saving video or thumbnail on my server. So I need to use streams for this. For thumbnail generation I use fluent-ffmpeg.

  Is it possible to get screenshots from streams using fluent-ffmpeg ?

  Is the correct way to intercept s3 getObject stream, that there was no need to download full video ?

  var config = require('../config');
  
  var AWS = require('aws-sdk');
  
  AWS.config.update({
  
    accessKeyId: config.AWS_accessKeyId,
  
    secretAccessKey: config.AWS_secretAccessKey,
  
    region: 'eu-west-1'
  
  });
  
  var s3 = new AWS.S3();
  
  var fs = require('fs');
  
  var ffmpeg = require('fluent-ffmpeg');
  
  
  
  exports.generateVideoThumbnail = function(fileId, url, done) {
  
    var params = {
  
      Bucket: config.AWS_bucket,
  
      Key: url
  
    };
  
    var input = s3.getObject(params);
  
    var stream = fs.createWriteStream('./screenshot.png');
  
    return ffmpeg(input).screenshots({
  
      timestamps: ['0.1', '0.2'],
  
      size: '200x200'
  
    }).output('./screenshot.png').output(stream).on('error', function(err) {
  
      return done(err);
  
    }).on('end', function() {
  
      input.close();
  
      var _key = "files/" + fileId + "/thumbnail.png";
  
      return s3.putObject({
  
        Bucket: config.AWS_bucket,
  
        Key: _key,
  
        Body: stream,
  
        ContentType: 'image/jpeg'
  
      }, function(err) {
  
        return done(err);
  
      });
  
    });
  
  };

• checkasm : Implement helpers for defining and checking padded rects

  21 mars, par Martin Storsjö

  checkasm : Implement helpers for defining and checking padded rects
  This backports similar functionality from dav1d, from commits
  
  35d1d011fda4a92bcaf42d30ed137583b27d7f6d and
  
  d130da9c315d5a1d3968d278bbee2238ad9051e7.
  This allows detecting writes out of bounds, on all 4 sides of
  
  the intended destination rectangle.
  The bounds checking also can optionally allow small overwrites
  
  (up to a specified alignment), while still checking for larger
  
  overwrites past the intended allowed region.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] tests/checkasm/checkasm.c
  • [DH] tests/checkasm/checkasm.h