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• Audio video duration matching for infinite dash loop pseudo live

  19 January 2020, by Massimo Vantaggio

  May I ask help to understand how to match audio and video duration during ffmpeg encoding for a concatenation of videos destined to an infinite loop mpeg dash transmission (mp4box).

  My issue happen during ffmpeg encoding:

  first step for audio encoding and timebase uniformity of each video before the concat/encode process:

  ffmpeg -y -i "$f" -c copy -video_track_timescale 90k -c:a aac -b:a 384k -ar 44100 -ac 2 -shortest -af aresample=async=1 ../buffer/${NAME}_buffer.mp4

  Then concat/encode process in order to get total duration in seconds multiple of closed GOP
  for example: cutting 373.5 duration to obtain 372.000 duration:

  ffmpeg -f concat -safe 0 -y -i list.txt -loop 1 -i ../logo/logo.png -c:a copy -c:v libx264 -x264opts keyint=$GOP:min-keyint=$GOP:no-scenecut -bf 0 -r $FPSC -b:v 4800k -maxrate 9600k -bufsize 19200k -profile:v main -crf 22 -filter_complex "[0:v][1:v]overlay=main_w-overlay_w-10:10,scale=1920:1080,setsar=1" -t $TOTDUR 1080set.mp4 

  the result

  VIDEO FORMAT CONTAINER DURATION:
  
  372.000000
  
  VIDEO STREAM DURATION:
  
  372.000000
  
  AUDIO FORMAT CONTAINER DURATION:
  
  372.006000

  I need help to understand why the audio duration counts 6 ms more than video duration and how to fix it.
  I read about loop_stream should help?
  Thanks a lot!

  Below the videos info:

  Metadata:
  
      major_brand     : isom
  
      minor_version   : 1
  
      compatible_brands: isomavc1
  
      creation_time   : 2007-05-09T07:55:25.000000Z
  
    Duration: 00:01:29.22, start: 0.000000, bitrate: 7490 kb/s
  
      Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1920x816, 7403 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc (default)
  
      Metadata:
  
        creation_time   : 2007-05-09T07:55:25.000000Z
  
        handler_name    : GPAC ISO Video Handler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 94 kb/s (default)
  
      Metadata:
  
        creation_time   : 2007-05-09T07:55:29.000000Z
  
        handler_name    : GPAC ISO Audio Handler
  
  
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 1
  
      compatible_brands: isomavc1
  
      creation_time   : 2007-07-17T09:18:37.000000Z
  
      genre           : Trailer
  
      artist          : Fox
  
      title           : The Simpsons Movie
  
      date            : 2007
  
    Duration: 00:02:17.25, start: 0.000000, bitrate: 8591 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x800, 8486 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc (default)
  
      Metadata:
  
        creation_time   : 2007-07-17T09:18:37.000000Z
  
        handler_name    : GPAC ISO Video Handler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, 5.1, fltp, 107 kb/s (default)
  
      Metadata:
  
        creation_time   : 2007-07-17T09:18:45.000000Z
  
        handler_name    : GPAC ISO Audio Handler
  
      Stream #0:2: Video: mjpeg (Progressive), yuvj420p(pc, bt470bg/unknown/unknown), 101x150 [SAR 72:72 DAR 101:150], 90k tbr, 90k tbn, 90k tbc (attached pic)
  
  
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isomavc1
  
      creation_time   : 2013-12-01T03:59:56.000000Z
  
      genre           : Trailer
  
      artist          : Warner Bros.
  
      title           : Gravity - 2K Trailer
  
      encoder         : HandBrake 0.9.9 2013051800
  
      date            : 2013
  
    Duration: 00:02:27.07, start: 0.000000, bitrate: 20296 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 2048x858, 20149 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc (default)
  
      Metadata:
  
        creation_time   : 2013-12-01T03:59:56.000000Z
  
        encoder         : JVT/AVC Coding
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 153 kb/s (default)
  
      Metadata:
  
        creation_time   : 2013-12-01T03:59:56.000000Z
  
      Stream #0:2: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/unknown), 102x150 [SAR 72:72 DAR 17:25], 90k tbr, 90k tbn, 90k tbc (attached pic)

• Bash script: automate ffmpeg encoding for mpeg-dash

  13 February 2018, by Massimo Vantaggio

  I’m writing a bash file to create video encoding and concatenation for dash live streaming use,
  Basically it read an input video folder, encodes all videos into three resolution formats, after that it concatening them to create three adaption sets.

  DIAGRAM:

  

  This script checks for fps conformance,

  force/scaling resolution if the input is not 1920 x 1080p,

  Insert the channel logo png,

  Cut the end of all videos input in order to make them finish with closed gop, this to ensure that there are not videos with audio and video track with different lenght.

  ISSUE:

  Actually I’m not sure that the concatenation process respects the closed GOP alignment as it after the encoding..
  I try to cut also the end of the concatenation result in order to make it finish without decimals on a closed gop too, but im unable to erase all decimals from the total duration:

  total duration in seconds: 826.795000
  
  total duration corrected in seconds: 826

  But the real duration measured by ffprobe is

  824.044000

  I try to check keyframes alignment with mp4box has they teach without any result:

  MP4Box -info TRACK_ID source1.mp4 2>&1 | grep GOP

  This is the first time that i work with "video scripts" and probably i don’t know what input to give for TRACK_ID

  BASH SCRIPT:

  #!/bin/bash
  
  #CANCAT 0.2
  
  
  
  cd input
  
  times=()
  
  fps=()
  
  for f in *.mp4; do
  
  
  
      _t=$(ffprobe -i "$f" -show_entries format=duration -v quiet -of csv="p=0")
  
      times+=("$_t")
  
  
  
      _f=$(ffmpeg -i "$f" 2>&1 | sed -n "s/.*, \\(.*\\) fp.*/\\1/p")
  
      fps+=("$_f")
  
  done
  
  #SUM ALL DURATIONS
  
  TOTALDURATION=$( echo "${times[@]}" | sed 's/ /+/g' | bc )
  
  #DELETE DECIMAL
  
  DURROUND=$(echo "$TOTALDURATION" | cut -d'.' -f1) 
  
  #GET REST OF DIVISION BY 2 AS GOP
  
  TOTDELTA="$((DURROUND%2))"
  
  #SUBTRACT DELTA FROM TOTAL DURATION
  
  TOTDUR="$(($DURROUND-$TOTDELTA))"
  
  
  
  #GET NUMBER OF ELEMENTS IN FPS ARRAY  
  
  tLen=${#fps[@]}
  
  #CHECK FPS EQUALITY     
  
  for tLen in "${fps[@]:1}"; do
  
      if [[ $tLen != ${fps[0]} ]]; then
  
          printf "WARNING: VIDEO’S FRAME-RATE ARE NOT EQUALS, THE PROCESS CAN’T START."
  
          printf "%s\\0" "${fps[@]}" |
  
              sort -zu |
  
              xargs -0 printf " %s"
  
          printf "\\n"
  
         exit 1
  
      fi
  
  done
  
  for f in *.mp4; do
  
  #GET DURATION OF EACH VIDEO
  
  DUR="$(ffprobe -i "$f" -show_entries format=duration -v quiet -of csv="p=0")"
  
  DUR=$(echo "$DUR" | cut -d'.' -f1) # DELETE DECIMAL
  
  #GET FPS OF EACH VIDEO
  
  FPS="$(ffmpeg -i "$f" 2>&1 | sed -n "s/.*, \(.*\) fp.*/\1/p")"
  
  #ROUND FPS OF EACH VIDEO
  
  FPSC=$( echo "($FPS+0.5)/1" | bc )
  
  #REMOVE EXTENSION FROM VIDEO FILE NAME
  
  NAME=$(echo "$f" | cut -d'.' -f1)
  
  
  
  #GET GOP
  
  GOP="$((FPSC*2))"
  
  DELTADUR="$((DUR%2))"
  
  DUR="$(($DUR-$DELTADUR))"
  
  
  
  #ENCODE 1080p
  
  ffmpeg -y -i "$f" -i ../logo/logo.png -c:a aac -b:a 384k -ar 48000 -ac 2 -async 1 -c:v libx264 -x264opts keyint=$GOP:min-keyint=$GOP:no-scenecut -bf 0 -r $FPSC -b:v 4800k -maxrate 4800k -bufsize 3000k -profile:v main -crf 22 -t $DUR -filter_complex "[0:v][1:v]overlay=main_w-overlay_w-10:10,scale=1920:1080,setsar=1" ../buffer/${NAME}-1080.mp4
  
  
  
  #ENCODE 720p
  
  ffmpeg -y -i ../buffer/${NAME}-1080.mp4 -c:a aac -b:a 256k -ar 48000 -ac 2 -async 1 -c:v libx264 -x264opts keyint=$GOP:min-keyint=$GOP:no-scenecut -bf 0 -s 1280x720 -r $FPSC -b:v 2400k -maxrate 2400k -bufsize 1500k -profile:v main -crf 22 -t $DUR ../buffer/${NAME}-720.mp4
  
  
  
  #ENCODE 360p
  
  ffmpeg -y -i ../buffer/${NAME}-720.mp4 -c:a aac -b:a 128k -ar 48000 -ac 2 -async 1 -c:v libx264 -x264opts keyint=$GOP:min-keyint=$GOP:no-scenecut -bf 0 -s 640x360 -r $FPSC -b:v 800k -maxrate 800k -bufsize 500k -profile:v main -crf 22 -t $DUR ../buffer/${NAME}-360.mp4
  
  done
  
  
  
  
  
  #enter in buffer
  
  cd ..
  
  cd buffer
  
  
  
  #CONCAT 1080 SET
  
  # with a bash for loop
  
  for f in ./*1080.mp4; do echo "file '$f'" >> 1080list.txt; done
  
  
  
  ffmpeg -f concat -safe 0 -i 1080list.txt -t $TOTDUR -c copy ../output/1080set.mp4
  
  
  
  #CONCAT 720 SET
  
  # with a bash for loop
  
  for f in ./*720.mp4; do echo "file '$f'" >> 720list.txt; done
  
  
  
  ffmpeg -f concat -safe 0 -i 720list.txt -t $TOTDUR -c copy ../output/720set.mp4
  
  
  
  #CONCAT 360 SET
  
  # with a bash for loop
  
  for f in ./*360.mp4; do echo "file '$f'" >> 360list.txt; done
  
  
  
  ffmpeg -f concat -safe 0 -i 360list.txt -t $TOTDUR -c copy ../output/360set.mp4
  
  
  
  #CLEAN BUFFER
  
  rm *.mp4
  
  rm *.txt
  
  
  
  echo "CONCAT COMPLETED:"
  
  echo "frame-rate: $fps"
  
  echo "total duration in seconds: $TOTALDURATION"
  
  echo "total duration corrected in seconds: $TOTDUR"

  The full file with relative folders:

  BASH SCRIPT WITH FOLDERS

  RESULT VIDEO

  There is someone who can help me to understand why I can not eliminate the decimals of the total duration during concat?
  And how to check overall keyframes allignment?
  Also any impovement that i ignore is welcome!

  Thanks a lot!

  Massimo

• Reading frames from MP4 segment (.m4s). or Dash Segment [closed]

  24 September 2020, by Vamsi Krishna Rayapati

  Generally we do it by

  


  copying init.mp4 and segment1.m4s to a video file and extract frames in that video

  


  It works fine. But it requires a temporary file

  


  I want to edit segment1.m4s directly

  


  ''' my idea is to decode the video
Direclty with out using init file '''

  


  Help me .how to do it ?