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• FFmpeg live rtmp capture to segments and encoding to mp4 is causing time glitches in the output

  19 août 2020, par ezwrighter

  I am having issues with capturing live video and converting the latest x minutes to a useable mp4 on demand.

  


  Currently i am capturing the latest 15m of a live rtmp stream and recording it with visual timestamp on it and saving it to segment files like this :

  


  ffmpeg -i rtmps://domain/myawesomestream.stream -map 0 -vf drawtext=x=10:y=10:shadowcolor=white:shadowx=1:shadowy=1:text='%{localtime\:%m/%d/%Y %H\\\:%M\\\:%S MST}' -vcodec libx264 -crf 21 -acodec copy -an -start_at_zero -f segment -segment_time 15 -segment_wrap 61 -segment_list_type ffconcat -segment_list_size 60 -segment_list bufferTime.ffcat -segment_format mpegts /dvr/captureTime-%03d.ts

  


  This works and allows me to always have the latest 15m of video captured with usable segments that I can then roll into mp4 files on demand like this without any re-encoding :

  


  /usr/bin/ffmpeg -safe 0 -f concat -i /dvr/bufferTime.ffcat -c copy -f mp4 /var/www/chat/dvr/ugb/fifteenminutesofvideo.mp4

  


  This does a great job of giving me the last 15 minutes of video from the live stream at any given moment. However, I would like to be able to get the last X minutes of video from the current segments instead of having to get the whole 15m minutes, without more encoding. I can sort of do it with two passes like this :

  


  /usr/bin/ffmpeg -safe 0 -f concat -i /dvr/bufferTime.ffcat -c copy -f mp4 -y /dvr/tmp/mywhole15minutes.mp4
/usr/bin/ffmpeg -sseof -120 -i /dvr/tmp/myshole15minutes.mp4 -c copy -f mp4 -y /dvr/my120secondsofvideo.mp4

  


  This gives me the last 120 seconds of video, but the front of the video has timestamp or keyframe issues at the front of it. It shows the visual timestamp between 5-12 seconds behind and then pauses or jumps the empty frames (Depending on the player) and then starts to play normally. I would love to fix the front of this video and have played with genpts and other flags to no avail :-( Any hints that might push me in the right direction ? Thanks ffmpeg pros out there ! I don't have a great place to publicly host the bad encoded video file, but would be happy to PM a link.

  


• Using ffmpeg (or similar) to print detailed h264 information

  26 octobre 2012, par gimmeamilk

  I have some h264 video in mpeg transport stream, and I suspect at certain points in the video it switches from 1080i/50Hz to 1080p/25Hz. I'd like to prove that using some video analysis tool. Can ffmpeg (or similar) print out such detailed decoding info ? I've tried ffmpeg setting "-loglevel debug" but it prints no more info about the actual decoding.

• Learning resources/tools for C# developer working with video streams

  27 août 2013, par JD.

  I am new to video streaming and would be grateful for any pointers on learning how to read/write/manipulate video streams.

  I am a C# developer (with no experiences in C++) so I wanted to know what tools/resources I could use to work with an Mpeg-ts transport stream ?

  What learning resources can be recommended and whether I can do everything I want without having to learn about DirectShow filters ?

  I read about FFMpeg which would be a good learning aid and hopefully this would do all I require in the future.