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• I am trying to save frames from a webcam via Python and ffmpeg, but the video becomes way to fast

  10 mai 2022, par Matthias

  I get a stream of cv2 images from my webcam and want to save it to a video file. After playing a bit with cv2.VideoWriter() it turned out that using ffmpeg would provide more options and - apparently, following a few threads here on SO - lead to better results. So I gave the VidGear Python library a try, and it seems to work fine.

  


  There is one catch though : My webcam provides a variable framerate, most of the time between 10 and 30 FPS. When saving these frames the video file becomes way too fast, like watching in fast-forward. One real-time minute becomes only a few seconds in the video.

  


  I tried to play with various combinations of the ffmpeg's -framerate and/or -r parameters, but without luck. Here is the command I am using right now :

  


  ffmpeg -y -f rawvideo -vcodec rawvideo -s 1920x1080 -pix_fmt bgra -framerate 25.0 -i - -vcodec libx265 -crf 25 -r 25 -preset fast 


  


  For the records, I am creating the WriteGear class from the VidGear library like this :

  


  video_params = {
    "-vcodec": "libx265",
    "-crf": 25,
    "-input_framerate": 25,
    "-r": 25,
}
WriteGear(output_filename=video_file, logging=True, **video_params)


  


  Any ideas what I am doing wrong here and how I need to call ffmpeg ?

  


• ffmpeg : What is the best practice to keep a live connection/socket with a camera, and save time on ffprobe

  15 mai 2022, par Jeff Strongman

  Today... I used the following command : with subprocess.PIPE and subprocess.Popen in python 3 :

  


  ffmpeg -i udp://{address_of_camera} \
  -vf select='if(eq(pict_type,I),st(1,t),gt(t,ld(1)))' setpts=N/FRAME_RATE/TB \
  -f rawvideo -an -vframes {NUM_WANTED_FRAMES} pipe:`


  


  This command helps me to capture NUM_WANTED_FRAMES frames from a live camera at a given moment.

  


  However... it takes me about 4 seconds to read the frames, and about 2.5 seconds to open a socket between my computer and the camera's computer.

  


  Is there a way, to have a socket/connection always open between my computer and the camera's computer, to save the 2.5 seconds ?

  


  I read something about fifo_size and overrun_fatal. I thought that maybe I can set fifo_size to be equal to NUM_WANTED_FRAMES, and overrun_fatal to True ? Will this solve my problem ? Or is there a different and simpler/better solution ?

  


  Should I try to record always (no -vframes flag) store the frames in a queue(With max size), and upon a wish to slice the video, read from my queue buffer ? Will it work well with the keyframe ?

  


  Also... What to do when ffmpeg fails ? restart the ffmpeg command ?

  


• FFmpeg unable to save file on Android : Output file #0 does not contain any stream

  16 mai 2022, par John M.

  I'm having difficulty when saving a RTSP stream into internal storage using ffmpeg-kit -i rtsp://192.168.100.60:554/stream1 -c:v copy -c:a copy -t 5 /data/user/0/com.arthenica.ffmpegkit.test/files/test.mp4. The command is called using FFmpegKit.executeAsync(command, ...). There're issues with the circular_buffer_size option, but I read that the warnings could be ignored. The command runs fine on desktop using ffmpeg. Please find below the log.

  


  Any advice would be appreciated.

  


  ffmpeg started on 2022-05-16 at 15:27:54
Report written to "/data/user/0/com.arthenica.ffmpegkit.test/cache/ffreport.txt"
Log level: 48
Command line:
ffmpeg-kit -i rtsp://192.168.100.60:554/stream1 -c:v copy -c:a copy -t 5 /data/user/0/com.arthenica.ffmpegkit.test/files/test.mp4
ffmpeg version v4.5-dev-3393-g30322ebe3c Copyright (c) 2000-2021 the FFmpeg developers
  built with Android (7155654, based on r399163b1) clang version 11.0.5 (https://android.googlesource.com/toolchain/llvm-project 87f1315dfbea7c137aa2e6d362dbb457e388158d)
  configuration: --cross-prefix=i686-linux-android- --sysroot=/files/android-sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/sysroot --prefix=/storage/light/projects/ffmpeg-kit/prebuilt/android-x86-lts/ffmpeg --pkg-config=/usr/bin/pkg-config --enable-version3 --arch=i686 --cpu=i686 --target-os=android --disable-neon --disable-asm --disable-inline-asm --ar=i686-linux-android-ar --cc=i686-linux-android16-clang --cxx=i686-linux-android16-clang++ --ranlib=i686-linux-android-ranlib --strip=i686-linux-android-strip --nm=i686-linux-android-nm --extra-libs='-L/storage/light/projects/ffmpeg-kit/prebuilt/android-x86-lts/cpu-features/lib -lndk_compat' --disable-autodetect --enable-cross-compile --enable-pic --enable-jni --enable-optimizations --enable-swscale --disable-static --enable-shared --enable-pthreads --enable-v4l2-m2m --disable-outdev=fbdev --disable-indev=fbdev --enable-small --disable-xmm-clobber-test --disable-debug --enable-lto --disable-neon-clobber-test --disable-programs --disable-postproc --  libavutil      57. 13.100 / 57. 13.100
  libavcodec     59. 15.102 / 59. 15.102
  libavformat    59. 10.100 / 59. 10.100
  libavdevice    59.  1.100 / 59.  1.100
  libavfilter     8. 21.100 /  8. 21.100
  libswscale      6.  1.102 /  6.  1.102
  libswresample   4.  0.100 /  4.  0.100
Splitting the commandline.
Reading option '-i' ... matched as input url with argument 'rtsp://192.168.100.60:554/stream1'.
Reading option '-c:v' ... matched as option 'c' (codec name) with argument 'copy'.
Reading option '-c:a' ... matched as option 'c' (codec name) with argument 'copy'.
Reading option '-t' ... matched as option 't' (record or transcode "duration" seconds of audio/video) with argument '5'.
Reading option '/data/user/0/com.arthenica.ffmpegkit.test/files/test.mp4' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Successfully parsed a group of options.
Parsing a group of options: input url rtsp://192.168.100.60:554/stream1.
Successfully parsed a group of options.
Opening an input file: rtsp://192.168.100.60:554/stream1.
[tcp @ 0xa21d3a80] No default whitelist set
[tcp @ 0xa21d3a80] Original list of addresses:
[tcp @ 0xa21d3a80] Address 192.168.100.60 port 554
[tcp @ 0xa21d3a80] Interleaved list of addresses:
[tcp @ 0xa21d3a80] Address 192.168.100.60 port 554
[tcp @ 0xa21d3a80] Starting connection attempt to 192.168.100.60 port 554
[tcp @ 0xa21d3a80] Successfully connected to 192.168.100.60 port 554
[rtsp @ 0xb25b5a00] SDP:
v=0
o=- 14665860 31787219 1 IN IP4 192.168.100.60
s=Session streamed by "MERCURY RTSP Server"
t=0 0
a=smart_encoder:virtualIFrame=1
m=video 0 RTP/AVP 96
c=IN IP4 0.0.0.0
b=AS:4096
a=range:npt=0-
a=control:track1
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1; profile-level-id=4D4020; sprop-parameter-sets=Z01AIJWgFAF34maIAAADAAgAAAMBlCA=,aO48gA==

Failed to parse interval end specification ''
[rtsp @ 0xb25b5a00] video codec set to: h264
[rtsp @ 0xb25b5a00] RTP Packetization Mode: 1
[rtsp @ 0xb25b5a00] RTP Profile IDC: 4d Profile IOP: 40 Level: 20
[rtsp @ 0xb25b5a00] Extradata set to 0xb25abdf0 (size: 35)
[rtp @ 0xb25abe60] No default whitelist set
[udp @ 0xb25abed0] No default whitelist set
[udp @ 0xb25abed0] 'circular_buffer_size' option was set but it is not supported on this build (pthread support is required)
[udp @ 0xb25abed0] end receive buffer size reported is 524288
[udp @ 0xb25abf40] No default whitelist set
[udp @ 0xb25abf40] 'circular_buffer_size' option was set but it is not supported on this build (pthread support is required)
[udp @ 0xb25abf40] end receive buffer size reported is 524288
[rtsp @ 0xb25b5a00] setting jitter buffer size to 500
[rtsp @ 0xb25b5a00] hello state=0
Failed to parse interval end specification ''
[h264 @ 0x907e5b00] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x907e5b00] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 0x907e5b00] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 0x907e5b00] nal_unit_type: 8(PPS), nal_ref_idc: 3
[rtsp @ 0xb25b5a00] Could not find codec parameters for stream 0 (Video: h264, none): unspecified size
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, rtsp, from 'rtsp://192.168.100.60:554/stream1':
  Metadata:
    title           : Session streamed by "MERCURY RTSP Server"
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0, 0, 1/90000: Video: h264, none, 90k tbr, 90k tbn
Successfully opened the file.
Parsing a group of options: output url /data/user/0/com.arthenica.ffmpegkit.test/files/test.mp4.
Applying option c:v (codec name) with argument copy.
Applying option c:a (codec name) with argument copy.
Applying option t (record or transcode "duration" seconds of audio/video) with argument 5.
Successfully parsed a group of options.
Opening an output file: /data/user/0/com.arthenica.ffmpegkit.test/files/test.mp4.
Output #0, mp4, to '/data/user/0/com.arthenica.ffmpegkit.test/files/test.mp4':
Output file #0 does not contain any stream