Pipe opencv frames into ffmpeg

Question

I am trying to pipe opencv frames into ffmpeg, but it does not work.

After the research, I found this answer (https://stackoverflow.com/a/62807083/10676682) to work the best for me, so I have the following:

def start_streaming_process(rtmp_url, width, height, fps):
    # fmt: off
    cmd = ['ffmpeg',
           '-y',
           '-f', 'rawvideo',
           '-vcodec', 'rawvideo',
           '-pix_fmt', 'bgr24',
           '-s', "{}x{}".format(width, height),
           '-r', str(fps),
           '-i', '-',
           '-c:v', 'libx264',
           '-pix_fmt', 'yuv420p',
           '-preset', 'ultrafast',
           '-f', 'flv',
           '-flvflags', 'no_duration_filesize',
           rtmp_url]
    # fmt: on

    return subprocess.Popen(cmd, stdin=subprocess.PIPE)

def main():
    width, height, fps = get_video_size(SOURCE_VIDEO_PATH)
    streaming_process = start_streaming_process(
        TARGET_VIDEO_PATH,
        width,
        height,
        fps,
    )

    model = load_yolo(WEIGHTS_PATH)
    frame_iterator = read_frames(video_source=SOURCE_VIDEO_PATH)
    processed_frames_iterator = process_frames(
        model, frame_iterator, ball_target_area=400
    )

    for processed_frame in processed_frames_iterator:
        streaming_process.communicate(processed_frame.tobytes())

    streaming_process.kill()

processed_frame here is an annotated OpenCV frame.

However, after I do my first streaming_process.communicate call, the ffmpeg process exits with code 0 (meaning everything was ok), but it is not. I can not feed the rest of the frames into ffmpeg, because the process exited.

Here are the logs:

Input #0, rawvideo, from 'fd:':
  Duration: N/A, start: 0.000000, bitrate: 663552 kb/s
  Stream #0:0: Video: rawvideo (BGR[24] / 0x18524742), bgr24, 1280x720, 663552 kb/s, 30 tbr, 30 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
[libx264 @ 0x132e05570] using cpu capabilities: ARMv8 NEON
[libx264 @ 0x132e05570] profile High, level 3.1, 4:2:0, 8-bit
[libx264 @ 0x132e05570] 264 - core 164 r3095 baee400 - H.264/MPEG-4 AVC codec - Copyleft 2003-2022 - h
ttp://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme
=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 
fast_pskip=1 chroma_qp_offset=-2 threads=15 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 inter
laced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=
1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbt
ree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, flv, to 'rtmp://global-live.mux.com:5222/app/9428e064-e5d3-0bee-dc67-974ba53ce164':
  Metadata:
    encoder         : Lavf60.3.100
  Stream #0:0: Video: h264 ([7][0][0][0] / 0x0007), yuv420p(tv, progressive), 1280x720, q=2-31, 30 fps
, 1k tbn
    Metadata:
      encoder         : Lavc60.3.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=    1 fps=0.0 q=29.0 Lsize=      41kB time=00:00:00.00 bitrate=N/A speed=   0x    eed=N/A    
video:40kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.678311%
[libx264 @ 0x132e05570] frame I:1     Avg QP:25.22  size: 40589
[libx264 @ 0x132e05570] mb I  I16..4: 37.7% 33.4% 28.9%
[libx264 @ 0x132e05570] 8x8 transform intra:33.4%
[libx264 @ 0x132e05570] coded y,uvDC,uvAC intra: 51.1% 53.2% 14.4%
[libx264 @ 0x132e05570] i16 v,h,dc,p: 32% 38% 20% 10%
[libx264 @ 0x132e05570] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 36% 28%  3%  2%  2%  3%  3%  6%
[libx264 @ 0x132e05570] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 18% 37% 17%  4%  4%  4%  5%  4%  7%
[libx264 @ 0x132e05570] i8c dc,h,v,p: 46% 37% 12%  4%
[libx264 @ 0x132e05570] kb/s:9741.36

That's all. Exit code 0.

Answer 1

The problem was in my read_frames function, which was a generator, and that somehow affected the whole program.