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• MPEG-DASH not working. MPD validation fails

  16 novembre 2017, par Marko36

  I am trying to serve video using MPEG-DASH. No success. I have tried the following :

  Following the instructions on webproject.org, using FFMPEG, I have created several variants of the original video and the DASH MPD manifest, containing metadata. However, the manifest does not validate using http://dashif.org/conformance.html. This validator itself is quite useless, as it provides unusable info about the error. I have found in a post from 2014, that one of the errors generated by FFMPEG is capital letters in some metadata (not a critical one, but could have been fixed for years !). Other errors detected, but not described. No tangible info from any of these other validators either : http://www-itec.uni-klu.ac.at/dash/?page_id=605 (produces rubbish info), https://github.com/Eyevinn/dash-validator-js (throws an exception)

  Following instructions on mozilla.org, produces the same non-working result, as the instructions are nearly identical (including same resolution*bitrate sets), except that Mozilla omits the use of dash.js, which is deemed necessary by the rest of the internet.

  This guide on Bitmovin, utilizing x264 and MP4Box does not work either. Going by the instructions, I have to recode the original x264 video twice. The final version of videos are in some cases twice the size of their intermediate versions and 720p video is actually larger than its 1080p, higher bitrate counterpart. No need to go further. (Yet, this is the only way that actually produced segments..)

  I have spent 3 days on the above, read about all there is on the web from the other frustrated adopters, and ran out of options. I would really apreciate some pro tips ! Thanks !

• How to merge webm video with mp4 video with transperency ?

  30 novembre 2017, par kostya572

  I have 1080p webm video and 500x300 mp4 video. How could I place muted mp4 video on top-center position of webm video with transparency ? The output file format needed ".webm". Here what similar code I found, but it uses two mp4 videos and second video scales full width on front of first one :

  ffmpeg \
       -i in1.mp4 -i in2.mp4 \
       -filter_complex " \
           [0:v]setpts=PTS-STARTPTS, scale=480x360[top]; \
           [1:v]setpts=PTS-STARTPTS, scale=480x360, \
                format=yuva420p,colorchannelmixer=aa=0.5[bottom]; \
           [top][bottom]overlay=shortest=1" \
       -vcodec libx264 out.mp4

  Output log :
  

• How to speed up black video creation with FFMPEG ?

  2 décembre 2017, par Rick Sullivan

  I have been generating static black videos as backgrounds using FFMPEG’s color source. This works fine for smaller and shorter videos, but I need to be able to generate long 1080p black videos quickly.

  For example, I can generate a two hour long 1080p@30fps video using :

  ffmpeg -f lavfi -i color=black:s=1920x1080:r=30 -t 7200 test.mp4

  But this will take over 45 minutes to run.

  There are options that speed up runtime, like using the ultrafast preset :

  ffmpeg -f lavfi -i color=black:s=1920x1080:r=30 -preset ultrafast -t 7200 test.mp4

  Which will take around 20 minutes to run. Better, but not good enough for doing this en masse.

  Are there any other options to drastically speed up runtime ?

  Intuitively, I am generating a static video where only video duration varies, so it seems like there should be an approach that is restricted only by disk write speed. All of these options are very CPU intensive and seem to be doing more processing than is necessary for my use case.