Estimating number of frames and fps in opencv

Question

I have some .mp4 video, ffmpeg shows me this info:

  Duration: 00:00:07.02, start: 0.000000, bitrate: 18001 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc, bt709/bt709/iec61966-2-1, progressive), 886x1920, 14299 kb/s, 22.54 fps, 60 tbr, 600 tbn, 1200 tbc (default)
    Metadata:
      rotate          : 270
      creation_time   : 2021-04-30T13:56:51.000000Z
      handler_name    : Core Media Video
      encoder         : 'avc1'
    Side data:
      displaymatrix: rotation of 90.00 degrees

So as I understand it should be 7.02 sec * 22.54 fps ~ 158 frames

When I try to read it in opencv:

def print_info_cap_reading(video_filepath):
    cap = cv2.VideoCapture(video_filepath)

    fps = cap.get(cv2.CAP_PROP_FPS)
    n_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))

    print('fps:', round(fps, 2))
    print('n_frames', n_frames)

    counter = 0
    while True:
        ret, frame = cap.read()
        if ret == False:
            break
        counter += 1

    print('counter:', counter)

It shows me

# fps: 22.54
# n_frames 199
# counter: 175

When I tried to convert it to separate frames via ffmpeg it produce 422 frames:

ffmpeg -i source1.mp4 tmp/img%03d.jpg

So I wonder:

Why fps is float value and not int value?
What is the right way to estimate fps and number of frames?
Why cv2.CAP_PROP_FRAME_COUNT in opencv and actually reading frames produce different number of frames?

Update:

-ignore_editlist 1 not helped, ffmpeg still produce 422 frames:

 ffmpeg -i source1.mp4 tmp1/img%03d.jpg
 ffmpeg -i source1.mp4 -ignore_editlist 1 tmp2/img%03d.jpg

Here is some ffmpeg output:

Output #0, image2, to 'tmp1/img%03d.jpg':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    com.apple.quicktime.author: ReplayKitRecording
    encoder         : Lavf58.45.100
    Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 1920x886, q=2-31, 200 kb/s, 60 fps, 60 tbn, 60 tbc (default)
    Metadata:
      encoder         : Lavc58.91.100 mjpeg
      creation_time   : 2021-04-30T13:56:51.000000Z
      handler_name    : Core Media Video
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
      displaymatrix: rotation of -0.00 degrees
frame=  422 fps=224 q=24.8 Lsize=N/A time=00:00:07.03 bitrate=N/A dup=247 drop=0 speed=3.74x
video:13709kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

Update:

mkdir tmp3 && ffmpeg -ignore_editlist 1 -i source1.mp4 tmp3/img%03d.jpg produce even more frames - 529.

Output #0, image2, to 'tmp3/img%03d.jpg':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    com.apple.quicktime.author: ReplayKitRecording
    encoder         : Lavf58.45.100
    Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 1920x886, q=2-31, 200 kb/s, 60 fps, 60 tbn, 60 tbc (default)
    Metadata:
      encoder         : Lavc58.91.100 mjpeg
      creation_time   : 2021-04-30T13:56:51.000000Z
      handler_name    : Core Media Video
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
      displaymatrix: rotation of -0.00 degrees
frame=  529 fps=221 q=24.8 Lsize=N/A time=00:00:08.81 bitrate=N/A dup=330 drop=0 speed=3.68x
video:16178kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

Estimating number of frames and fps in opencv

0 Answers