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• H.264 video file size from camera is much bigger than x264 output

  10 août 2020, par Lawrence song

  I have a UVC camera which supports h264 protocol. we can see the h264 listed below when we list all formats supported.

  


  msm8909:/data # ./ffmpeg -f v4l2 -list_formats all -i /dev/video1
ffmpeg version N-53546-g5eb4405fc5-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libxml2 --enable-libxvid --enable-libzimg
  libavutil      56. 56.100 / 56. 56.100
  libavcodec     58. 97.100 / 58. 97.100
  libavformat    58. 49.100 / 58. 49.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
[video4linux2,v4l2 @ 0x4649140] Compressed:        h264 :                H.264 : 1920x1080 1280x720 640x480 320x240
[video4linux2,v4l2 @ 0x4649140] Compressed:       mjpeg :                MJPEG : 1920x1080 1280x720 640x480 320x240


  


  I am running the ffmpeg cmd to record UVC camera video to local device.

  


  ffmpeg -f v4l2 -input_format h264 -framerate 30 -video_size 1280*720 -i /dev/video1 -c copy /sdcard/Movies/output.mkv


  


  The video size is way bigger than running the command below :

  


  ffmpeg -f v4l2 -input_format mjpeg -framerate 30 -video_size 1280*720 -i /dev/video1 -c:v libx264 -vf format=yuv420p /sdcard/Movies/output.mp4


  


  I assume the camera already supports h264 protocol. Thus I don't need to re-encode to 264 formats. However, the video size does not look like an H264 encoded video.

  


• ffmpeg v4l2(UVC camera) stream h264 video to local device

  10 août 2020, par Lawrence song

  I have a UVC camera which supports h264 protocol. we can see the h264 listed below when we list all formats supported.

  


  msm8909:/data # ./ffmpeg -f v4l2 -list_formats all -i /dev/video1
ffmpeg version N-53546-g5eb4405fc5-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libxml2 --enable-libxvid --enable-libzimg
  libavutil      56. 56.100 / 56. 56.100
  libavcodec     58. 97.100 / 58. 97.100
  libavformat    58. 49.100 / 58. 49.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
[video4linux2,v4l2 @ 0x4649140] Compressed:        h264 :                H.264 : 1920x1080 1280x720 640x480 320x240
[video4linux2,v4l2 @ 0x4649140] Compressed:       mjpeg :                MJPEG : 1920x1080 1280x720 640x480 320x240


  


  I am running the ffmpeg cmd to record UVC camera video to local device.

  


  ffmpeg -f v4l2 -input_format h264 -framerate 30 -video_size 1280*720 -i /dev/video1 -c copy /sdcard/Movies/output.mkv


  


  The video size is way bigger than running the command below :

  


  ffmpeg -f v4l2 -input_format mjpeg -framerate 30 -video_size 1280*720 -i /dev/video1 -c:v libx264 -vf format=yuv420p /sdcard/Movies/output.mp4


  


  I assume the camera already supports h264 protocol. Thus I don't need to re-encode to 264 formats. However, the video size does not look like an H264 encoded video.

  


• is there a faster way to extract various video clips from different sources and concatenate them, using moviepy ?

  27 août 2019, par user2627082

  So I’ve made a small script using moviepy to help me with my video editing process. It basically scans a bunch of subtitle files for specified words and the time duration when it occurs. With that it extracts that particular time duration from video files corresponding to the subtitle files. The extracted mp4 clips are all concatenated and written into one big composition.

  So it’s all running fine but it’s very slow. Can someone tell me it’s possible to make it faster. Am I doing something wrong ? Or is it normal for the process to be slow.

  import os,re
  
  from pathlib import Path
  
  from moviepy.editor import *
  
  import datetime
  
  
  
  
  
  def search(words_list, sub_list):
  
  
  
      for x in range(len(words_list)):
  
          print(words_list[x])
  
          clips = []
  
          clips.clear()
  
          for y in range(len(sub_list)):
  
              print(sub_list[y])
  
              stamps = []
  
              stamps.clear()
  
  
  
  
  
              with open(sub_list[y]) as f:
  
                  paragraphs = (paragraph.split("\n") for paragraph in 
  
              f.read().split("\n\n"))
  
  
  
              for paragraph in paragraphs:
  
                  if any(words_list[x] in line.lower() for line in paragraph):
  
                      stamps.append(f"[{paragraph[1].strip()}]")
  
  
  
              videopath = str(sub_list[y]).replace("srt", "mp4").replace(":\\", 
  
              ":\\\\")
  
              my_clip = VideoFileClip(videopath)
  
  
  
  
  
              for stamp in stamps:
  
                  print(stamp)
  
                  pre_stamp =  stamp[1:9]
  
                  post_stamp = stamp[18:26]
  
                  format = '%H:%M:%S'
  
  
  
                  pre_stamp  = str(datetime.datetime.strptime(pre_stamp, format) 
  
                  -   datetime.timedelta(seconds=4))[11:19]
  
                  post_stamp = str(datetime.datetime.strptime(post_stamp,format) 
  
                  + datetime.timedelta(seconds=4))[11:19]
  
  
  
                  trim_clip = my_clip.subclip(pre_stamp,post_stamp)
  
                  clips.append(trim_clip)
  
                  conc = concatenate_videoclips(clips)
  
          print(clips)
  
          conc.write_videofile("C:\\Users\Sri\PycharmProjects\subscrape\movies\\" + words_list[x] + "-comp.mp4")
  
  
  
  
  
  
  
  
  
  words = ["does what","spins","size"]
  
  
  
  subs = list(Path('C:\\Users\Sri\PycharmProjects\subscrape\movies').glob('**/*.srt'))
  
  
  
  search(words,subs)