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• How can I best utilize an AWS service to segment a video into smaller chunks and then combine them back to together ? [on hold]

  19 avril 2018, par Justin Malin

  I am trying to do processing on videos uploaded to AWS S3 using an AWS Lambda function in Python. However, FFmpeg and ffmpeg-python (as far as I am aware) are unable to process objects and must do processing on stored files. Lambda only allows for 500 MB of storage in the /tmp/ folder, thus limiting the size of video that I can do processing on.

  If there is an alternative to FFmpeg that allows me to work on object files that I am unaware of, that would be a reasonable solution because I can scale up the memory of the Lambda function (although there is still a limit).

  Alternatively, I have looked into segmenting the video using AWS Elastic Transcoder, but I do not think I can dynamically segment the video using that service. If there is a service similar to this that could segment the video into individual frames (and back), that would be even better.

  I have also considered using AWS EC2, but I would only be using the EC2 service to segment videos sporadically, so it would be a waste to constantly have a server that capable running. If I use the AWS Elastic Beanstalk, would it automatically start a more powerful instance of EC2 to do the video segmentation (and reformation) when that is called and revert back to a much smaller instance when dormant ?

  Essentially, I would like to know if there are any services (preferably within AWS) that allow me to segment a video into shorter videos or into each frame at-will.

• Create MPEG-DASH Initialization segment

  5 janvier 2016, par Mahout

  I am looking to convert between HLS and MPEG Dash. I do not access to the original fully concatenated video file, only the individual HLS segments.

  In doing this transformation to MPEG Dash I need to supply an initialziation segment for the Dash manifest .mpd file.

  My questions are :

  1. What is the structure of a Dash video initialization segment ?
  2. How can I generate/create one without the need for the original full file ?

  Perhaps a solution would involve getting MP4Box to convert the ’.ts’ HLS segments to Dash ’.m4s’ segments which are self initializing, but I am unsure how to go about this this ?

  Any ideas are much appreciated.

  Many thanks.

  UPDATE :
  Snippet to stream using original hls segments. Video plays all the way through but is just black.

    <representation width="426" height="238" framerate="25" bandwidth="400000">
  
      <segmentlist timescale="25000" duration="112500">
  
             <segmenturl media="video_0_400000/hls/segment_0.ts"></segmenturl>
  
             <segmenturl media="video_0_400000/hls/segment_1.ts"></segmenturl>
  
            <segmenturl media="video_0_400000/hls/segment_2.ts"></segmenturl>
  
      </segmentlist>
  
     </representation>

• avcodec/g729dec : Use 64bit and clip in scalar product

  5 novembre 2019, par Michael Niedermayer

  avcodec/g729dec : Use 64bit and clip in scalar product
  The G729 reference decoder clips after each individual operation and keeps track if overflow
  
  occurred (in the fixed point implementation), this here is
  
  simpler and faster but not 1:1 the same what the reference does.
  Non fuzzed samples which trigger any such overflow are welcome, so
  
  the need and impact of different clipping solutions can be evaluated.
  Fixes : signed integer overflow : 1271483721 + 1073676289 cannot be represented in type 'int'
  
  Fixes : 18617/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ACELP_KELVIN_fuzzer-5137705679978496
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/g729dec.c