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• HLS implementation with FFmpeg

  6 juin 2017, par Joseph K

  I am trying to implement HLS using FFmpeg for transcoding + segmenting but have been facing a couple of issues that have been bugging me for the past week.

  Issue

  Webserver currently receives live MP4 fragments being recorded on-the-go and needs to take care of transcoding and segmentation.

  As mp4 fragments are being received, they need to be encoded. Then segmented. If i run a segmenter (be it ffmpeg or apple mediastreamsegmenter), every mp4 fragment is being treated as a VOD by itself and I’m not being able to integrate them as part of a larger live event implementation.

  I thought of a solution where every time I receive an mp4 fragment, I first use fmpeg to concatenate it with previous ones to form the larger mp4 that I then pass to be segmented for HLS. That did not work either because the entire stream has to be re-segmented each and every time and existing TS fragments replaced by new ones that are similar yet shifted in time.

  Implementation 1

  ffmpeg -re -i fragmentX.mp4 -b:v 118k -b:a 32k -vcodec copy -preset:v veryfast -acodec aac -strict -2 -ac 2 -f mpegts -y fragmentX.ts

  I manage the m3u8 manifest on my own, deleting old fragments and appending new ones.

  When validating the stream, I find it stacked with EXT-X-DISCONTINUITY tags making the stream unwatchable.

  Implementation 2

  First combine latest fragment with overall.mp4

  ffmpeg -i "concat:newfragment.mp4|existing.mp4" -c copy overall.mp4

  Then pass the combination to ffmpeg for HLS segmentation

  ffmpeg -re -i overall.mp4 -ac 2 -r 20 -vcodec libx264 -b:v 318k -preset:v veryfast -acodec aac -strict -2 -b:a 32k -hls_time 2 -hls_list_size 3 -hls_allow_cache 0 -hls_base_url /Users/JosephKalash/Desktop/test/350/ -hls_segment_filename ’350/fragment%03d.ts’ -hls_flags delete_segments 350/index.m3u8

  Concatenation is not perfect and there are noticeable glitches where the fragments are supposed to be stitched. Segmentation replaces older fragments and the manifest is rewritten as if it’s a new HLS stream every time ffmpeg is called.

  I cannot figure out how to get this to work properly.

  Any ideas ?

• Anomalie #3523 : Gestion des plugins avec spip 3.0.20

  5 août 2015, par Gilles VINCENT

  en ajoutant la directive
  

  opcache.validate_timestamps=0

  à ma config php, comme conseillé dans http://wiki.mikejung.biz/PHP_OPcache pour un serveur en production, la page de gestion des plugins refonctionne à nouveau correctement. De plus, la valeur
  

  opcache.revalidate_freq=60

  (valeur par défaut fournie lors de l’install) est vraiment longue.
  Si je commente cette ligne dans le fichier de config, le phpinfo() indique une valeur plus raisonnable de 2 seulement.
  Je pense que le chargement méga long venait de cette constante.

  La différence de comportement avec la config "pour développement" entre une 3.0.19 et une 3.0.20 reste encore surprenante.
  Si j’ai le temps, je creuserai dans une semaine à mon retour de vacance, car tout le monde ne peut as jouer avec ces paramètres du serveur... :/

• run ffmpeg commands from my own project

  28 octobre 2013, par bruno

  I'm starting a project where I want ppl to upload videos of a talk and a the video of slides for that talk and want to merge them (to play at the same time) and then show results.

  My question is :
  Is it possible to do that from code ? if it is, can you point me to the right doc ?
  I was able to do it running command line, but as I want this to run on a server with different ppl uploading their videos I think this would not be the best approach.
  I have a preference for Java if it's possible to do it, but I can manage to use other languages what do you guys suggest ?

  The idea would be to have a service where I can point the urls of the videos stored in my server and it would merge them and save file where I can later stream. With different ppl uploading videos at the same time and being able to watch the result in a reasonable amount of time.

  I used this tutorial to test :
  https://trac.ffmpeg.org/wiki/Create%20a%20mosaic%20out%20of%20several%20input%20videos

  Thanks for your time