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• Video with drop frames with ffmpeg

  28 mai 2018, par Gabe Mata

  I am recording videos using ffmpeg in a production environment almost non-stop for 15 hours a day. Sometimes the videos are freezing for a few seconds.

  I believe the hardware is adequate. It is an i7 with 16GB ram and windows 10. The videos are on average about 2:00 minute each.

  This happens a few times a day 10 or so that I am awarded.

  Here is a link to one of the videos that froze :

  https://drive.google.com/open?id=1q6R2l1AkCko-uh2KZ6X8AChdGU5XBOy7

  It freezes at 0:03 and then restarts at 0:16

  Here is the ffmpeg command I am using :

  ffmpeg -i "rtsp ://10.0.131.2/media/video1" -f segment -segment_time 9000 -segment_format mp4 -reset_timestamps 1 -strftime 1 -c copy -map 0 gabe.mp4

  Can I decreases the quality of the videos so videos don’t randomly freeze ?

  Would recording without audio help the videos not randomly freeze ?

  Thanks,

  Gabe

• ffmpeg dash Segment offset

  18 mars 2019, par inkubux

  I’m trying to integrate live-transcoding like "plex" or "emby" with my application.

  I am able to serve dash content over to shaka-player or dash.js but only in ’live-mode’. But I want to enable seeking through the player.

  I looked at plex and to enable this they create their own mpd file with duration so the player will have a full seekbar.

  However when seeking the player will ask for a segment number eg : 449. I need to stop ffmpeg and restart with an offset (-ss &lt;<segment>>)</segment>, but ffmpeg will just restart a transcode session from segment 0 with an initial segment.

  What I want is to tell ffmpeg to start at a seekpoint but only output from segment number and now-on.

  When playing with hls and mpegts, I can tell ffmpeg to output at a certain segment : with the option -segment_start_number but this is not available for dash. And plex use their own transcoder based of ffmpeg with the option -skip_to_segment

  I tried to ’hack’ around by keeping a manual offset on my web-server, even if I serve the "supposed" right segment after the seek point dash.js and shaka-player can’t recover the stream.. VLC on the other habd is able to (probably more tolerent) to errors in segments.

  Is the supposed right segment after a seek in dash (contains the initial segment) or only the segment.

  Is ffmpeg able to start segmenting dash as a supposed segment (for seek and resume)

  The same technique works in hls with forced key frames and a custom m3u8 (with all the "predicted" segments) but calculating the right segment length and the right bandwidth is much harder and hackish and dash is more tolerant to variation.

  I would really like to be able to seek through my live transcoding video.

  For reference here is a custom mpd file I serve to enable "seeking" :

  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" suggestedpresentationdelay="PT1S" mediapresentationduration="PT49M2.920S" maxsegmentduration="PT2S" minbuffertime="PT10S">
  
      <period start="PT0S" duration="PT49M2.920S">
  
          <adaptationset segmentalignment="true">
  
              <segmenttemplate timescale="1" duration="1" initialization="$RepresentationID$/initial.mp4" media="$RepresentationID$/$Number$.m4s" startnumber="1">
  
              </segmenttemplate>
  
              <representation mimetype="video/mp4" codecs="avc1.640029" bandwidth="3766000" width="1920" height="1080">
  
              </representation>
  
          </adaptationset>
  
          <adaptationset segmentalignment="true">
  
              <segmenttemplate timescale="1" duration="1" initialization="$RepresentationID$/initial.mp4" media="$RepresentationID$/$Number$.m4s" startnumber="1">
  
              </segmenttemplate>
  
              <representation mimetype="audio/mp4" codecs="mp4a.40.2" bandwidth="188000" audiosamplingrate="48000">
  
                  <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="6"></audiochannelconfiguration>
  
              </representation>
  
          </adaptationset>
  
      </period>
  
  </mpd>

  And here is the ffmpeg command to pull it off :

  ffmpeg -ss 0 -i movie.mkv -y -acodec aac -vcodec libx264 -f dash -min_seg_duration 1000000 -individual_header_trailer 0 -pix_fmt yuv420p -vf scale=trunc(min(max(iw\,ih*dar)\,1920)/2)*2:trunc(ow/dar/2)*2 -bsf:v h264_mp4toannexb -profile:v high -level 4.1 -map_chapters -1 -map_metadata -1 -preset veryfast -movflags frag_keyframe+empty_moov -use_template 1 -use_timeline 0 -remove_at_exit 1 -crf 23 -bufsize 7532k -maxrate 3766k -start_at_zero -threads 0 -force_key_frames expr:if(isnan(prev_forced_t),eq(t,t),gte(t,prev_forced_t+1)) -init_seg_name $RepresentationID$/0_initial.mp4 -media_seg_name $RepresentationID$/0_$Number$.m4s /transcoding_temp/Z1GVWEc/index.mpd

  The media_seg_name is where I prepend the custom seek_point let’s say I want to seek to segment 1233 the template would be :

  -media_seg_name $RepresentationID$/1233_$Number$.m4s

  and the segments would be 1233_1 1233_2 1233_* So I can serve the right segment after seek. but the player does not recover and still downloading subsequent segments. I guess since a new initial segment is generated and I somehow miss headers for continuous playback after seek but I’m probably wrong.

  Thanks for your help

• Video recorded using Kurento is corrupted

  10 avril 2023, par Pranjal Lamba

  We are using Kurento media server v6.6.1 to record a video conference. The web app client which runs on Chrome(Windows, OSX, Android) is using a modified version of one-to-one-call-advanced Kurento sample and the second client is an Android native application which is using Nubomedia webrtcpeer v1.1.1. Nubomedia webrtcpeer uses LibJingle built by io.pristine v11139(released on December 2015). The video and audio is recorded in two separate recorder endpoints by Kurento.

  


  Video conference recordings generated using web app client/s are working properly. But sometimes the video generated using native application contains all the frames within initial few seconds. Please find below download link for the problematic video generated by our Android native application,

  


  https://drive.google.com/file/d/1vOVk8hPuP_iOlQfsmMoqZLhICy-Jpcee/view?usp=sharing

  


  We are testing this feature on a range of Android devices, Nexus 5(Android 6.0.1), Nexus 6(Android 7.1.1), Sony Xperia Z Tablet(Android 6.0.1), Samsung Galaxy Tab A(Android 5.0), OnePlus 3(Android 7.1.1), Xiaomi A1(Android 7.1.1). The issue randomly starts occurring on a bunch of these devices while the others work properly and vice-versa.

  


  We are recording the videos with the following constraints,

  


  Web app client

  


  Minimum video width : 32
  
Minimum video height : 32
  
Maximum video width : 320
  
Maximum video height : 320
  
Minimum framerate : 1
  
Maximum framerate : 15
  
Video container format : MP4
  
Video codec : H.264
  
Audio codec : AAC

  


  Android native client

  


  Minimum video width : 32
  
Minimum video height : 32
  
Maximum video width : 480
  
Maximum video height : 640
  
Minimum framerate : 1
  
Maximum framerate : 25
  
Video container format : MP4
  
Video codec : H.264
  
Audio codec : Opus