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• 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)

• Watson NarrowBand Speech to Text not accepting ogg file

  19 janvier 2017, par Bob Dill

  NodeJS app using ffmpeg to create ogg files from mp3 & mp4. If the source file is broadband, Watson Speech to Text accepts the file with no issues. If the source file is narrow band, Watson Speech to Text fails to read the ogg file. I’ve tested the output from ffmpeg and the narrowband ogg file has the same audio content (e.g. I can listen to it and hear the same people) as the mp3 file. Yes, in advance, I am changing the call to Watson to correctly specify the model and content_type. Code follows :

  exports.createTranscript = function(req, res, next)
  
  { var _name = getNameBase(req.body.movie);
  
    var _type = getType(req.body.movie);
  
    var _voice = (_type == "mp4") ? "en-US_BroadbandModel" : "en-US_NarrowbandModel" ;
  
    var _contentType = (_type == "mp4") ? "audio/ogg" : "audio/basic" ;
  
    var _audio = process.cwd()+"/HTML/movies/"+_name+'ogg';
  
    var transcriptFile = process.cwd()+"/HTML/movies/"+_name+'json';
  
  
  
    speech_to_text.createSession({model: _voice}, function(error, session) {
  
      if (error) {console.log('error:', error);}
  
      else
  
        {
  
          var params = { content_type: _contentType, continuous: true,
  
           audio: fs.createReadStream(_audio),
  
            session_id: session.session_id
  
            };
  
            speech_to_text.recognize(params, function(error, transcript) {
  
              if (error) {console.log('error:', error);}
  
              else
  
                { fs.writeFile(transcriptFile, JSON.stringify(transcript), function(err) {if (err) {console.log(err);}});
  
                  res.send(transcript);
  
                }
  
            });
  
        }
  
    });
  
  }

  _type is either mp3 (narrowband from phone recording) or mp4 (broadband)
  model: _voice has been traced to ensure correct setting
  content_type: _contentType has been traced to ensure correct setting

  Any ogg file submitted to Speech to Text with narrowband settings fails with Error: No speech detected for 30s. Tested with both real narrowband files and asking Watson to read a broadband ogg file (created from mp4) as narrowband. Same error message. What am I missing ?