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• Evolution #3426 : enrichir la détection des robots

  19 novembre 2018, par BoOz -

  Attention aussi à la regexp "google" qui peut chopper https://user-agents.net/string/mozilla-5-0-linux-android-4-2-1-en-us-nexus-5-build-jop40d-applewebkit-535-19-khtml-like-gecko-googleweblight-chrome-38-0-1025-166-mobile-safari-535-19

• ffmpeg - two very similar webm files, two very different conversion speeds to mp4

  28 juin 2018, par Nuthinking

  I generate webm files in two different ways. One using Chrome WebRTC MediaRecorder, the other one is using a js library which generates the webm video frame by frame (webm-writer-js). The file size of the videos generated is not that different, the fast one is 60% of the slow one but the difference in speed is 1000%

  Using the basic ffmpeg syntax -i input.webm output.mp4 the files created with Chrome’s media recorder take in fact almost 10x time to be converted. The conversion logs differ slightly but overall look very similar to my novice eyes. On the left the fast conversion and on the right the slow one.

  

  The fast one throws a little error but the conversion seems successful. In the slow conversion you can see many frames processed, in the fast one as if there was only one (very fast). Using -preset veryfast cuts the speed time by half to both but the loss of quality is visible.

  Any idea how I could speed up the conversion for the videos generated by Chrome without compromising much in quality ? Thanks a lot !

• Encoding FFMPEG to MPEG-DASH – or WebM with Keyframe Clusters – for MediaSource API

  6 août 2018, par Chris Nolet

  I’m currently sending a video stream to Chrome, to play via the MediaSource API.

  As I understand it, MediaSource only supports MP4 files encoded with MPEG-DASH, or WebM files that have clusters beginning with keyframes (otherwise it raises the error : Media segment did not begin with keyframe).

  Is there any way to encode in MPEG-DASH or keyframed WebM formats with FFMPEG in real-time ?

  Edit :

  I just tried it with ffmpeg ... -f webm -vcodec vp8 -g 1 so that every frame is a keyframe. Not the ideal solution. It does work with MediaStream now though. Any way to sync up the segments with the keyframes in WebM so not every frame needs to be a keyframe ?

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  Reference Questions on WebM / MP4 and MediaSource :

  Media Source Api not working for a custom webm file (Chrome Version 23.0.1271.97 m)

  MediaSource API and mp4