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• How to properly abort av_seek_frame on FFmpeg ?

  5 mars 2021, par SuRGeoNix

  Normally, you wouldn't care aborting av_seek_frame as it would be really fast on a local file. However, in my case I use a custom AVIOContext for torrent streaming with custom read/seek functions and I'm not able to abort a single seek request !

  


  I've already tried interrupt callbacks (they will not be called at all), some timeouts (rw_timeout/timeout etc.) but by checking FFmpeg's code didn't find anything at all. My last chance was to try to return on read/seek functions an error (I've tried AVERROR_EXIT) which causes even more problems (memory leaks).

  


  The main issue is with Matroska formats that they need to resync (level-1) and they are trying to scan the whole file.

  


  Unfortunately, I'm using C# .NET with FFmpeg.Autogen bindings which means that I don't have low-level access to play around. My workaround is to re-open the whole format context in case on seek abort (to ensure that the player will continues to play at least)

  


  Hope you have a tip for me !

  


  (By the way for some http/hls web formats interrupt callbacks are supported)

  


• Have 2 blocking scripts interact with each other in linux

  18 novembre 2014, par Ortixx

  I have 2 blocking shell scripts which I want to have interact with each other. The scripts in question are peerflix (nodejs script) and ffmpeg (a simple bash script).

  What happens : Peerflix fires up, feeds data to ffmpeg bash scrip which terminates peerflix on completion.

  So once peerflix starts it outputs 2 lines and blocks immediately :

  [08:15 PM]-[vagrant@packer-virtualbox-iso]-[/var/www/test]-[git master] 
  
  $ node /var/www/test/node/node_modules/peerflix/app.js /var/www/test/flexget/torrents/test.torrent -r -q
  
  listening: http://10.0.2.15:38339/
  
  process: 9601

  I have to feed the listening address to the ffmpeg bash script :

  #!/bin/sh
  
  ffmpeg -ss 00:05:00 -i {THE_LISTENING_PORT} -frames:v 1 out1.jpg
  
  ffmpeg -ss 00:10:00 -i {THE_LISTENING_PORT} -frames:v 1 out2.jpg

  After the bash script is done I have to kill the peerflix script (hence me outputting the PID).

  My question is how do I achieve this ?

• How can I build a custom version of opencv while enabling CUDA and opengl ?

  1er avril, par Josh

  I have a hard requirement of python3.7 for certain libraries (aeneas & afaligner). I've been using the regular opencv-python and ffmpeg libraries in my program and they've been working find.

  


  Recently I wanted to adjust my program to use h264 instead of mpeg4 and ran down a licensing rabbit hole of how opencv-python uses a build of ffmpeg with opengl codecs off to avoid licensing issues. x264 is apparently opengl, and is disabled in the opencv-python library.

  


  In order to solve this issue, I built a custom build of opencv using another custom build of ffmpeg both with opengl enabled. This allowed me to use the x264 encoder with the VideoWriter in my python program.

  


  Here's the dockerfile of how I've been running it :

  



  FROM python:3.7-slim

# Set optimization flags and number of cores globally
ENV CFLAGS="-O3 -march=native -ffast-math -flto -fno-fat-lto-objects -ffunction-sections -fdata-sections" \
    CXXFLAGS="-O3 -march=native -ffast-math -flto -fno-fat-lto-objects -ffunction-sections -fdata-sections" \
    LDFLAGS="-flto -fno-fat-lto-objects -Wl,--gc-sections" \
    MAKEFLAGS="-j\$(nproc)"

# Combine all system dependencies in a single layer
RUN apt-get update && apt-get install -y --no-install-recommends \
    build-essential \
    cmake \
    git \
    wget \
    unzip \
    yasm \
    pkg-config \
    libsm6 \
    libxext6 \
    libxrender-dev \
    libglib2.0-0 \
    libavcodec-dev \
    libavformat-dev \
    libswscale-dev \
    libavutil-dev \
    libswresample-dev \
    nasm \
    mercurial \
    libnuma-dev \
    espeak \
    libespeak-dev \
    libtiff5-dev \
    libjpeg62-turbo-dev \
    libopenjp2-7-dev \
    zlib1g-dev \
    libfreetype6-dev \
    liblcms2-dev \
    libwebp-dev \
    tcl8.6-dev \
    tk8.6-dev \
    python3-tk \
    libharfbuzz-dev \
    libfribidi-dev \
    libxcb1-dev \
    python3-dev \
    python3-setuptools \
    libsndfile1 \
    libavdevice-dev \
    libavfilter-dev \
    libpostproc-dev \
    && apt-get clean \
    && rm -rf /var/lib/apt/lists/*

# Build x264 with optimizations
RUN cd /tmp && \
    wget https://code.videolan.org/videolan/x264/-/archive/master/x264-master.tar.bz2 && \
    tar xjf x264-master.tar.bz2 && \
    cd x264-master && \
    ./configure \
        --enable-shared \
        --enable-pic \
        --enable-asm \
        --enable-lto \
        --enable-strip \
        --enable-optimizations \
        --bit-depth=8 \
        --disable-avs \
        --disable-swscale \
        --disable-lavf \
        --disable-ffms \
        --disable-gpac \
        --disable-lsmash \
        --extra-cflags="-O3 -march=native -ffast-math -fomit-frame-pointer -flto -fno-fat-lto-objects" \
        --extra-ldflags="-O3 -flto -fno-fat-lto-objects" && \
    make && \
    make install && \
    cd /tmp && \
    # Build FFmpeg with optimizations
    wget https://ffmpeg.org/releases/ffmpeg-7.1.tar.bz2 && \
    tar xjf ffmpeg-7.1.tar.bz2 && \
    cd ffmpeg-7.1 && \
    ./configure \
        --enable-gpl \
        --enable-libx264 \
        --enable-shared \
        --enable-nonfree \
        --enable-pic \
        --enable-asm \
        --enable-optimizations \
        --enable-lto \
        --enable-pthreads \
        --disable-debug \
        --disable-static \
        --disable-doc \
        --disable-ffplay \
        --disable-ffprobe \
        --disable-filters \
        --disable-programs \
        --disable-postproc \
        --extra-cflags="-O3 -march=native -ffast-math -fomit-frame-pointer -flto -fno-fat-lto-objects -ffunction-sections -fdata-sections" \
        --extra-ldflags="-O3 -flto -fno-fat-lto-objects -Wl,--gc-sections" \
        --prefix=/usr/local && \
    make && \
    make install && \
    ldconfig && \
    rm -rf /tmp/*

# Install Python dependencies first
RUN pip install --no-cache-dir --upgrade pip setuptools wheel && \
    pip install --no-cache-dir numpy py-spy

# Build OpenCV with optimized configuration
RUN cd /tmp && \
    # Download specific OpenCV version archives
    wget -O opencv.zip https://github.com/opencv/opencv/archive/4.8.0.zip && \
    wget -O opencv_contrib.zip https://github.com/opencv/opencv_contrib/archive/4.8.0.zip && \
    unzip opencv.zip && \
    unzip opencv_contrib.zip && \
    mv opencv-4.8.0 opencv && \
    mv opencv_contrib-4.8.0 opencv_contrib && \
    rm opencv.zip opencv_contrib.zip && \
    cd opencv && \
    mkdir build && cd build && \
    cmake \
        -D CMAKE_BUILD_TYPE=RELEASE \
        -D CMAKE_C_FLAGS="-O3 -march=native -ffast-math -flto -fno-fat-lto-objects -ffunction-sections -fdata-sections" \
        -D CMAKE_CXX_FLAGS="-O3 -march=native -ffast-math -flto -fno-fat-lto-objects -ffunction-sections -fdata-sections -Wno-deprecated" \
        -D CMAKE_EXE_LINKER_FLAGS="-flto -fno-fat-lto-objects -Wl,--gc-sections" \
        -D CMAKE_SHARED_LINKER_FLAGS="-flto -fno-fat-lto-objects -Wl,--gc-sections" \
        -D CMAKE_INSTALL_PREFIX=/usr/local \
        -D ENABLE_FAST_MATH=ON \
        -D CPU_BASELINE_DETECT=ON \
        -D CPU_BASELINE=SSE3 \
        -D CPU_DISPATCH=SSE4_1,SSE4_2,AVX,AVX2,AVX512_SKX,FP16 \
        -D WITH_OPENMP=ON \
        -D OPENCV_ENABLE_NONFREE=ON \
        -D WITH_FFMPEG=ON \
        -D FFMPEG_ROOT=/usr/local \
        -D OPENCV_EXTRA_MODULES_PATH=/tmp/opencv_contrib/modules \
        -D PYTHON_EXECUTABLE=/usr/local/bin/python3.7 \
        -D PYTHON3_EXECUTABLE=/usr/local/bin/python3.7 \
        -D PYTHON3_INCLUDE_DIR=/usr/local/include/python3.7m \
        -D PYTHON3_LIBRARY=/usr/local/lib/libpython3.7m.so \
        -D PYTHON3_PACKAGES_PATH=/usr/local/lib/python3.7/site-packages \
        -D PYTHON3_NUMPY_INCLUDE_DIRS=/usr/local/lib/python3.7/site-packages/numpy/core/include \
        -D BUILD_opencv_python3=ON \
        -D INSTALL_PYTHON_EXAMPLES=OFF \
        -D BUILD_TESTS=OFF \
        -D BUILD_PERF_TESTS=OFF \
        -D BUILD_EXAMPLES=OFF \
        -D BUILD_DOCS=OFF \
        -D BUILD_opencv_apps=OFF \
        -D WITH_OPENCL=OFF \
        -D WITH_CUDA=OFF \
        -D WITH_IPP=OFF \
        -D WITH_TBB=OFF \
        -D WITH_V4L=OFF \
        -D WITH_QT=OFF \
        -D WITH_GTK=OFF \
        -D BUILD_LIST=core,imgproc,imgcodecs,videoio,python3 \
        .. && \
    make && \
    make install && \
    ldconfig && \
    rm -rf /tmp/*

# Set working directory and copy application code
WORKDIR /app

COPY requirements.txt .

RUN apt-get update && apt-get install -y --no-install-recommends ffmpeg

RUN pip install --no-cache-dir aeneas afaligner && \
    pip install --no-cache-dir -r requirements.txt

COPY . .

# Make entrypoint executable
RUN chmod +x entrypoint.sh
ENTRYPOINT ["./entrypoint.sh"]


  


  My trouble now, is I've been considering running parts of my program on my GPU, it's creating graphics for a video after all. I have no idea how to edit my Dockerfile to make the opencv build run with CUDA enabled, every combination I try leads to issues.

  


  How can I tell which version of CUDA, opencv and ffmpeg are compatible with python 3.7 ?