使用 OpenCV 和 ffmpeg 后端编码 HEVC 视频

我尝试使用带有 ffmpeg 后端的 OpenCV 和 Python3 将网络摄像头编码为 HEVC 视频。 它可以与其他编解码器配合使用，例如mjpg。 这是我的示例脚本，它使用相应的fourcc（也尝试过hevc, h265, x265, etc.):

#!/bin/python3

import cv2
import time
import subprocess

def video(seconds, frameRate):
    cap = cv2.VideoCapture(0)
    if(not cap.isOpened()):
        return "error"

    # Define the codec and create VideoWriter object
    fourcc = cv2.VideoWriter_fourcc(*'HEVC')
    name = "/tmp/" + time.strftime("%d-%m-%Y_%X")+".hevc"
    out = cv2.VideoWriter(name, fourcc, frameRate, (640,480))
    program_starts = time.time()
    result = subprocess.Popen(["ffprobe", name], stdout = subprocess.PIPE, stderr = subprocess.STDOUT, shell=True)
    nFrames=0
    while(nFrames<seconds*frameRate):
        ret, frame = cap.read()
        if ret==True:
            out.write(frame)
            nFrames += 1
        else:
            break
    cap.release()
    return name 
# Store a video to /tmp for 2 seconds
print(video(2,15))

返回错误：

OpenCV: FFMPEG: tag 0x43564548/'HEVC' is not found (format 'hevc / raw HEVC video')'

我的Ubuntu系统配置如下：

bash> cat /etc/issue
Ubuntu 16.04.6 LTS \n \l

bash> python3 -m pip list | grep opencv
opencv-contrib-python-nonfree 4.1.1.1               
opencv-python-nonfree         4.1.1.1

bash> ffmpeg -encoders
ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
  configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  libavutil      54. 31.100 / 54. 31.100
  libavcodec     56. 60.100 / 56. 60.100
  libavformat    56. 40.101 / 56. 40.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 40.101 /  5. 40.101
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.101 /  1.  2.101
  libpostproc    53.  3.100 / 53.  3.100
Encoders:
...
 V..... libx265              libx265 H.265 / HEVC (codec hevc)
...

事实证明Python3opencv-*-nonfree软件包附带其自己的 FFmpeg。不过，我准备了一个最小的脚本，假设所有开发库都已安装，则构建 OpenCV，该脚本与本地安装的 FFmpeg 和 HEVC（及其他）链接：安装脚本.

安装后（bash> make install），我可以通过运行提到的脚本

bash> ln -s /opt/opencv/ffmpeg/lib/python3.5/dist-packages/cv2/python-3.5/cv2.cpython-35m-x86_64-linux-gnu.so /opt/opencv/ffmpeg/lib/python3.5/dist-packages/cv2/cv2.so
bash> export PYTHONPATH=/opt/opencv/ffmpeg/lib/python3.5/dist-packages/
bash> export LD_LIBRARY_PATH=/opt/opencv/ffmpeg/lib
bash> python3 /tmp/test_encoding.py
x265 [info]: HEVC encoder version 1.9
x265 [info]: build info [Linux][GCC 5.3.1][64 bit] 8bit+10bit+12bit
x265 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX AVX2 FMA3 LZCNT BMI2
x265 [info]: Main profile, Level-3.1 (Main tier)
x265 [info]: Thread pool created using 4 threads
x265 [info]: frame threads / pool features       : 1 / wpp(8 rows)
x265 [warning]: Source height < 720p; disabling lookahead-slices
x265 [info]: Coding QT: max CU size, min CU size : 64 / 8
x265 [info]: Residual QT: max TU size, max depth : 32 / 1 inter / 1 intra
x265 [info]: ME / range / subpel / merge         : hex / 57 / 2 / 2
x265 [info]: Keyframe min / max / scenecut       : 15 / 250 / 40
x265 [info]: Lookahead / bframes / badapt        : 20 / 4 / 2
x265 [info]: b-pyramid / weightp / weightb       : 1 / 1 / 0
x265 [info]: References / ref-limit  cu / depth  : 3 / 1 / 1
x265 [info]: AQ: mode / str / qg-size / cu-tree  : 1 / 1.0 / 32 / 1
x265 [info]: Rate Control / qCompress            : ABR-9216 kbps / 0.60
x265 [info]: tools: rd=3 psy-rd=2.00 signhide tmvp strong-intra-smoothing
x265 [info]: tools: deblock sao
x265 [info]: frame I:      1, Avg QP:1.89  kb/s: 22236.48
x265 [info]: frame P:      8, Avg QP:6.27  kb/s: 14486.10
x265 [info]: frame B:     21, Avg QP:8.79  kb/s: 12282.91
x265 [info]: Weighted P-Frames: Y:75.0% UV:75.0%
x265 [info]: consecutive B-frames: 11.1% 11.1% 33.3% 22.2% 22.2% 

encoded 30 frames in 5.27s (5.69 fps), 13202.21 kb/s, Avg QP:7.89
/tmp/25-11-2019_23:13:04.mov

此外，非常重要的是 fourcc（就我而言）hvc1 for HEVC）是正确的，并且容器支持编解码器（在我的例子中mov).

最终/tmp/test_encoding.py的内容

#!/bin/python3

import cv2
import time
import subprocess

def video(seconds, frameRate):
    cap = cv2.VideoCapture(0)
    if(not cap.isOpened()):
        return "error"

    # Define the codec and create VideoWriter object
    fourcc = cv2.VideoWriter_fourcc(*'hvc1')
    name = "/tmp/" + time.strftime("%d-%m-%Y_%X")+".mov"
    out = cv2.VideoWriter(name, fourcc, frameRate, (640,480))
    program_starts = time.time()
    result = subprocess.Popen(["ffprobe", name], stdout = subprocess.PIPE, stderr = subprocess.STDOUT, shell=True)
    nFrames=0
    while(nFrames<seconds*frameRate):
        ret, frame = cap.read()
        if ret==True:
            out.write(frame)
            nFrames += 1
        else:
            break
    cap.release()
    return name 
# Store a video to /tmp for 2 seconds
print(video(2,15))