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• How can I make sure trimming in ffmpeg with -c:v copy is accurate

  9 avril 2020, par Angelo

  I looked at many things online and I understand it's better to re-encode if you want precision.

  



  But for instance, I have the following command :

  



  -ss 00:00:09 -i "input.mp4" -c:v copy -c:a copy -vframes 600 "output.mp4


  



  Where 600 is calculated using the video's FPS and duration, in this case 10 seconds from an 60FPS video. Can I expect to get something accurate with this all the time ? I tested many variants but this seems to be doing ok for the couple videos I tested for.. And if not, can I really ever get complete ACCURACY with copying, or must I stick to H264 for instance ?

  


• opencv cannot read MP4 file from sony camcorder

  7 juin 2016, par Jundong

  The sony camcorder recorded video in MP4 format. I am reading the file by

  import cv2
  
  vid = cv2.VideoCapture('sample.MP4')

  my OpenCV version is 2.4.8, as a Python module.

  The codec of the ’sample.MP4’ is H.264, Linear PCM.

  ffprobe sample.MP4

  returns :

  > Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C0004.mp4':   Metadata:
  
  >     major_brand     : XAVC
  
  >     minor_version   : 16785407
  
  >     compatible_brands: XAVCmp42iso2
  
  >     creation_time   : 2016-06-06 13:41:51   Duration: 00:00:15.02, start: 0.000000, bitrate: 50439 kb/s
  
  >     Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/bt709/iec61966-2-4), 1920x1080 [SAR 1:1 DAR 16:9],
  
  > 48655 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
  
  >     Metadata:
  
  >       creation_time   : 2016-06-06 13:41:51
  
  >       handler_name    : Video Media Handler
  
  >       encoder         : AVC Coding
  
  >     Stream #0:1(und): Audio: pcm_s16be (twos / 0x736F7774), 48000 Hz, 2 channels, s16, 1536 kb/s (default)
  
  >     Metadata:
  
  >       creation_time   : 2016-06-06 13:41:51
  
  >       handler_name    : Sound Media Handler
  
  >     Stream #0:2(und): Data: none (rtmd / 0x646D7472), 245 kb/s (default)
  
  >     Metadata:
  
  >       creation_time   : 2016-06-06 13:41:51
  
  >       handler_name    : Timed Metadata Media Handler 
  
  > Unsupported codec with id 0 for input stream 2

  It seems that the codec for h.264 is missing. The version of my FFmpeg is 3.0.

  I tried avconv -i sample.MP4 -c:a copy -c:v copy sample_converted.mp4 to convert the sample.MP4 to sample_converted.mp4, this command line did not work. The command ffmpeg -i sample.mp4 sample_converted.mp4 worked ; however, it compromised the video quality badly.I used an online video converter : http://www.online-convert.com/ (which output nice quality video in mp4 format, but it has size limitation for free users)
  to convert the MP4 to mp4, the command in Terminal as below :

  ffprobe 'sample_converted.mp4'

  returns

  > Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C0001_converted.mp4':  
  
  > Metadata:
  
  >     major_brand     : isom
  
  >     minor_version   : 512
  
  >     compatible_brands: isomiso2avc1mp41
  
  >     encoder         : Lavf57.36.100   Duration: 00:00:02.02, start: 0.000000, bitrate: 16777 kb/s
  
  >     Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 16801 kb/s, 59.94
  
  > fps, 59.94 tbr, 60k tbn, 119.88 tbc (default)
  
  >     Metadata:
  
  >       handler_name    : VideoHandler
  
  >     Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
  
  >     Metadata:
  
  >       handler_name    : SoundHandler

  Obviously, the encoders, handler_names etc. of the sample.MP4 and sample_converted.mp4 are different. Any idea using FFmpeg or OpenCV to convert this raw video from camcorder to the readable format without compromising the video quality ?

• Split Video Files Batch Mac

  11 août 2022, par dolomite41

  Noob Here. I have about 300 files that I want to split into segments. About 5 seconds each. I figured how to do it for one file, but is there anyway I can do it to the whole folder directory ? Been searching online and can't seem to find exactly what I need.

  


  here is what I did for the single file

  


  ffmpeg -i test2.mp4 -c copy -map 0 -segment_time 00:0:05 -f segment output%03d.mp4

  


  would like to do it for all the files at once

  


  

  1. Is there a batch command that can do it for all files

  


  2. If not, is there a way I can put more than one command line into Terminal and run them all at once ?

  


  


  OS - Mac - Monterey - FFMPEG and Brew installed

  


  Real noobie, any help would be appreciated