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• ffmpeg muxing 6 mono wavs and prores mov into new 6 channel mov - how to ?

  23 octobre 2017, par BabaG

  i’ve been dealing with this for a day now and finally have to just come out and ask. i want to take a prores mov file that is silent (but apparently does have a timecode track) and losslessly mux it with 6 mono wav files, having the 6 mono wavs become 6 uncompressed channels (not 6 streams) in the final mov.

  how do i do this ?

  the attempts i’ve made have all failed in some way or other. either i get a conflict where a filter is employed which prevents a direct copy, or i get an error in mapping, or something else. i’ve seen lots on working with either a single audio channel and picture but nothing on muxing 5.1 with picture. either that or there is transcoding being done but not straight copying. also found a lot on extracting but nothing much on combining.

  here’s the last command i tried, which gave me an aac audio track with the correct number of channels but, obviously, was not just a copy of the uncompressed wavs :

  ffmpeg -i pix.mov -i L.wav -i R .wav -i C.wav -i LFE.wav -i Ls.wav -i Rs.wav -filter_complex "[1:a][2:a][3:a][4:a][5:a][6:a]amerge=inputs=6[aout]" -map "[aout]" -c:v copy -c:a copy muxed51.mov

  this threw the error that -filter_complex is incompatible with -c:a copy, which makes sense now that i’ve seen it. without the -c:a copy switch i got an mp4 mov with no picture and aac audio. i think i tried it also with the -filter_complex parameters running from 0-5 rather than the 1-6 as they are here. i think i was trying to leave room for the video stream to copy into the 0 space. obviously not a coder here. i just need to get this done and it seemed like it should be pretty simple. not turning out that way.

  to sum up, how do i just copy the video and 6 mono wavs into a mov container with the audio as 6 channels ? both picture and audio should be lossless copies.

  thanks,
  BabaG

• cv2.videoCapture() return always false, also skvideo.io.VideoCapture()

  26 juillet 2022, par Selin Gök

  I read nearly all of questions about this subject but I didn't solve it.
I am working on Linux/Mint. I tried to open my webcam (or any video it does not matter) with opencv and read a frame from the video. And I write this code :

  



  import cv2

cap = cv2.VideoCapture(0)

while(True):
    ret, frame = cap.read()
    print ret #It returns always false

    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    cv2.imshow('frame',gray)
    if cv2.waitKey(1) & 0xFF == ord('q'):
       break

cap.release()
cv2.destroyAllWindows()


  



  —> I read the problem might can be because of opencv installation. I checked the installation, it seems true. When I write 'pip freeze', the result list contained opencv-python module so I thought the installation is correct and it isn't the reason for my problem.

  



  —> I tried to change the index in videoCapture(0) to -1 and 1, and it again failed.

  



  —> And then, I read that the other cause can be FFmpeg or codec. But I also installed FFmpeg and the problem didn't change.

  



  —> cv2.VideoCapture() didn't give any error but I want to install cv2 module on the Poject>Settings>Project Interpreter, it gave me an error (executed command : pip install cv2) But when I run this command, it gave me this error : Could not find a version that satisfies the requirement cv2 (from versions : ) No matching distribution found for cv2
I checked the cv2 module in my virtualenv and it seems there. (/cv_env/lib/python2.7/site-packages/cv2)

  



  —> I also tried it with "skvideo.io.VideoCapture()" but I failed again.

  



  So, I didn't understand the problem and I am really new in this subject. 
What is the problem ?

  


• ffmpeg : how to determine frame rate automatically ?

  24 septembre 2021, par mrgloom

  I use this simple script to convert video to images using ffmpeg, but frame rate is fixed, how can I determine it automatically ?

  



  FRAME_RATE="30"
SEPARATOR='/'


VIDEO_PATH=$1

VIDEO_BASE_DIR=`dirname $1`
FRAMES_DIR=$VIDEO_BASE_DIR$SEPARATOR"Frames"
rm -rf $FRAMES_DIR
mkdir $FRAMES_DIR

#Convert video to images
./ffmpeg -r $FRAME_RATE -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d.png"


  



  UPDATE :

  



  By ffprobe I checked that my 1st video frame rate is 30.
Also results are the same (339 frames are produced) even I reduce frame rate, so -r option doesn't work or work in some other way ?

  



  These command give the same result :

  



  ./ffmpeg -r 10 -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d"$EXTENSION
./ffmpeg -r 30 -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d"$EXTENSION
./ffmpeg -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d"$EXTENSION


  



  Output :

  



  ffmpeg version N-63893-gc69defd Copyright (c) 2000-2014 the FFmpeg developers
  built on Jul 16 2014 05:38:01 with gcc 4.6 (Debian 4.6.3-1)
  configuration: --prefix=/root/ffmpeg-static/64bit --extra-cflags='-I/root/ffmpeg-static/64bit/include -static' --extra-ldflags='-L/root/ffmpeg-static/64bit/lib -static' --extra-libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3 --enable-libvpx
  libavutil      52. 89.100 / 52. 89.100
  libavcodec     55. 66.101 / 55. 66.101
  libavformat    55. 43.100 / 55. 43.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  8.100 /  4.  8.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/user/myvideo1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2016-01-16 05:30:03
  Duration: 00:00:11.33, start: 0.000000, bitrate: 4659 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x480, 4539 kb/s, SAR 65536:65536 DAR 4:3, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      rotate          : 90
      creation_time   : 2016-01-16 05:30:03
      handler_name    : VideoHandle
    Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s (default)
    Metadata:
      creation_time   : 2016-01-16 05:30:03
      handler_name    : SoundHandle
Output #0, image2, to '/home/user/Frames/image%d.png':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    encoder         : Lavf55.43.100
    Stream #0:0(eng): Video: png, rgb24, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 30 fps, 90k tbn, 30 tbc (default)
    Metadata:
      rotate          : 90
      creation_time   : 2016-01-12 05:38:03
      handler_name    : VideoHandle
      encoder         : Lavc55.66.101 png
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> png (png))
Press [q] to stop, [?] for help
frame=  339 fps= 68 q=0.0 Lsize=N/A time=00:00:11.30 bitrate=N/A    
video:195852kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown