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• Linking PHP audio and video uploads to FFMPEG on a linux server

  21 janvier 2016, par user5399793

  I host a site on a Linux server that I built with php where I am able to upload audio files in one section and video files to another. Each section uses php to upload a single audio file and a single video file. Each upload is assigned a unique filename so they can be viewed separately on an individual page where the uploader can post comments about their audio or video. I want to be able to allow musicians and performers in the local area display their work. The site works, but large video files do not upload and my audio player only plays a few formats, and I like to convert them all to mp3’s. I installed ffmpeg on my linux server to help me with this and am able to connect to it with my terminal. My question is how do I get ffmpeg to interface with my uploaded php files. For example, as the user uploads an audio file, can I have ffmpeg convert it while it’s uploading, or do I need to set up a temporary folder for uploads, store it there, then have ffmpeg compress the file, convert it to a specific format and save it in another folder ? I would prefer to have it compress and change the format while it’s uploading so as not to use server space, but if this is not the way ffmpeg works, then I don’t have a choice. Any help would be appreciated.

• How to losslessly compress a sequence of slowly-changing images into a video ?

  26 juillet 2023, par Claude C

  I have a sequence of jpeg images captured like a timelapse, with the same dimension and changing slowly in order. I want to compress the size of the whole sequence while still able to recover each individual image with their raw pixel information unchanged.

  


  I googled and found that a possible solution is to compress it into a video, which exploits the strong temporal correlation (inter-frame redundancy) between consecutive frames, as suggested here. I tried ffmpeg libx264 but none of the option combinations seem to preserve frame quality and compress total size at the same time (-crf 0 keeps the quality but the size of the video is even larger than the input sequence).

  


  So my questions is,

  


  

  • What is the correct way to losslessly compress a sequence of slowly-changing images ?

  


  


  I can accept using softwares other than ffmpeg (as long as it is on windows or linux), doing color space conversion on raw images (if necessary). It is OK if a the compression is done without converting to videos. Thank you.

  


• avfilter/vf_unsharp : Don't dereference NULL

  1er décembre 2019, par Andreas Rheinhardt

  avfilter/vf_unsharp : Don't dereference NULL
  The unsharp filter uses an array of arrays of uint32_t, each of which is
  
  separately allocated. These arrays also need to freed separately ; but
  
  before doing so, one needs to check whether the array of arrays has
  
  actually been allocated, otherwise one would dereference a NULL pointer.
  
  This fixes #8408.
  Furthermore, the array of arrays needs to be zero-initialized so that
  
  no uninitialized pointer will be freed in case an allocation of one of
  
  the individual arrays fails.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavfilter/vf_unsharp.c