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• Cut videos and stack them with hstack in ffmpeg at the same time

  18 juillet 2018, par ekuusi

  I have two videos that I want to stack with hstack. The videos are not perfectly in sync so I would like to cut a bit from the beginning of one of the videos to get them to sync perfectly. Everything works fine using two concurrent commands :

  ffmpeg -ss 00:00:18 -i video1.mp4 -ss 00:00:02.000 -c:v libx264 left.mp4 

  followed by

  ffmpeg -i left.mp4 -i right.mp4 -filter_complex hstack output.mp4

  I’m wondering however if it is possible to do the trimming at the same time as stacking so that ffmpeg doesn’t have to encode the cut video twice. This would save a lot of time for me as I will be doing this cutting & merging multiple times.

  I tried various ways to achieve this in one single command, but to no avail so I have to turn to the community. Thank you for helping !

• ffmpeg transcoding reset the start time of file

  12 août 2013, par diousk

  I use a segmenter to segment my MPEG 2 Ts file into a series of media segment for HTTP live streaming

  and each segment's start time following the previous one
  (ex:start time of segments : 00:00,00:10,00:20,00:30,...)

  (In Ubuntu)

  The Question is :

  When I use ffmpeg to transcode one of the media segment (ex 800k bps to 200k bps)

  the start time of transcoded media segment will be reset to 0

  ex:As I transcode the third segement,

  start time of segments changing to : 00:00,00:10,00:00,00:30,...

  It cause my player freezing once play the transcoded media segment

  Is there any solution to transcode media file with the same start time ?

  I guess it's the ffmpeg reset the PTS(presentation timestamp) of segment

  But I don't know how to fix it...

  here is my ffmpeg command (transcode to 250k bps)

  ============================

  ffmpeg -y -i sample-03.ts -f mpegts -acodec libfaac -ar 48000 -ab 64k -vcodec libx264 -b 250k -flags +loop -cmp +chroma \
  
   -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 0 -refs 0 -coder 0 -me_range 16 -keyint_min 25 \
  
   -sc_threshold 40 -i_qfactor 0.71 -maxrate 250k -bufsize 250k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 \
  
   -qmin 10 -qmax 51 -qdiff 4 -level 30 -aspect 320:240 -g 30 -async 2 sample.ts

  ============================

  Help !

  thanks

• stop ffmpeg stream at specific time of the day

  28 juillet 2022, par drake7

  This stream will stop after 3600 seconds with the -t option.

  


  Is it possible to stop the stream at a certain time of the day, e.g. at 1:00 A.M. using ffmpeg only ?

  


  ffmpeg -f dshow -i video="Virtual-Camera" -preset ultrafast -vcodec libx264 -tune zerolatency -b 900k \
-f mpegts -t 3600 udp://10.1.0.102:1234


  


  The Docs are very clear about the syntax for Time duration.

  


  So something like -t (1+1) doesn't work. It is not evaluated to -t 2.

  


  I think Expression Evaluation doesn't help either because it seems to be only valid in filters.

  


  A simple bash solution to stop at 01:00 AM would be :

  


  # Set time to stop
# maximum value is 23:59:59
# use `offset_tomorrow` to set a time tomorrow
time_to_stop="23:59:59"

# remaining seconds until 1 AM
offset_tomorrow=3601

# calculate time difference between maximum time and now and add offset in seconds.
# add 1 hour and 1 minute to get the remaining seconds until 1 AM.
seconds_to_stop=$((`date -d$time_to_stop '+%s'`-`date '+%s'` + $offset_tomorrow))

ffmpeg -f dshow -i video="Virtual-Camera" -preset ultrafast -vcodec libx264 -tune zerolatency -b 900k \
-f mpegts -t $seconds_to_stop udp://10.1.0.102:1234