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• Piping OpenCV raw video frames into FFMpeg results in corrupted output

  27 novembre 2023, par Dudad

  I have written a python script to open my webcam in OpenCV and convert captured frames to video streams. I have followed some tutorials that basically do these things :

  


  

  1. Creating a pipe input to FFMpeg

  


  2. Writing OpenCV video frames into the pipe. FFMpeg should then encode and output the video.

  


  


  In my case, FFMpeg runs without errors, and using imshow() displays captured frames correctly, but the FFMpeg video output is corrupted.

  


  imshow()
video output

  


  code :

  


  import cv2 as cv
import subprocess as sp

FPS = 24
WIDTH = 720
HEIGHT = 360

cap = cv.VideoCapture(0)
cap.set(cv.CAP_PROP_FPS, FPS)
cap.set(cv.CAP_PROP_FRAME_WIDTH, WIDTH)
cap.set(cv.CAP_PROP_FRAME_HEIGHT, HEIGHT)

# ffmpeg command
ffmpeg_cmd = [
    "./libs/ffmpeg/bin/ffmpeg.exe",
    '-hwaccel', 'auto', '-y',
    '-f', 'rawvideo',
    '-vcodec','rawvideo',
    '-pix_fmt', 'bgr24',
    '-s', f"{WIDTH}x{HEIGHT}",
    '-r', str(FPS),
    '-i', '-',
    '-c:v', 'libx264',
    '-pix_fmt', 'yuv420p',
    '-preset', 'ultrafast',
    '-f', 'flv',
    'out.flv'
]
ffmpeg_sp = sp.Popen(ffmpeg_cmd, stdin=sp.PIPE)

while True:
    ret,frame = cap.read()
    # video capture test: OK
    cv.imshow('video', frame)
    if cv.waitKey(50)&0xFF == ord('q'):
        break
    #frame = cv.cvtColor(frame, cv.COLOR_BGR2YUV)   # It doesn't work
    # write to ffmpeg pipe
    ffmpeg_sp.stdin.write(frame.tobytes())

ffmpeg_sp.stdin.close()
cap.release()
cv.destroyAllWindows()


  


  I'm running Python 3.11.5, OpenCV 4.8.0.76 on Windows 11. The ffmpeg -version output is given below.

  


  ffmpeg version N-112841-g2d9ed64859-20231125 Copyright (c) 2000-2023 the FFmpeg developers
built with gcc 13.2.0 (crosstool-NG 1.25.0.232_c175b21)
configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 --disable-debug --disable-w32threads --enable-pthreads --enable-iconv --enable-libxml2 --enable-zlib --enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig --enable-libharfbuzz --enable-libvorbis --enable-opencl --disable-libpulse --enable-libvmaf --disable-libxcb --disable-xlib --enable-amf --enable-libaom --enable-libaribb24 --enable-avisynth --enable-chromaprint --enable-libdav1d --enable-libdavs2 --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --enable-frei0r --enable-libgme --enable-libkvazaar --enable-libaribcaption --enable-libass --enable-libbluray --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librist --enable-libssh --enable-libtheora --enable-libvpx --enable-libwebp --enable-lv2 --enable-libvpl --enable-openal --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-librav1e --enable-librubberband --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm --enable-vaapi --enable-libvidstab --enable-vulkan --enable-libshaderc --enable-libplacebo --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-ldflags=-pthread --extra-ldexeflags= --extra-libs=-lgomp --extra-version=20231125
libavutil      58. 32.100 / 58. 32.100
libavcodec     60. 34.100 / 60. 34.100
libavformat    60. 17.100 / 60. 17.100
libavdevice    60.  4.100 / 60.  4.100
libavfilter     9. 13.100 /  9. 13.100
libswscale      7.  6.100 /  7.  6.100
libswresample   4. 13.100 /  4. 13.100
libpostproc    57.  4.100 / 57.  4.100


  


  I have been playing around with FFMpeg arguments for a while and none of them works. I have also transcoded video files using FFMpeg successfully. It somehow just doesn't work with raw video frames from OpenCV. Any help/advice is appreciated.

  


• Can't fix this ffmpeg, NoClassDefFoundError org.bytedeco.ffmpeg.global.avutil

  16 mars 2023, par noob234

  I am trying to get the video duration with this library import org.bytedeco.javacv.FFmpegFrameGrabber;

  


  When I upload this mp4 video (https://sample-videos.com/video123/mp4/720/big_buck_bunny_720p_1mb.mp4), I get this error message :
java.lang.NoClassDefFoundError: Could not initialize class org.bytedeco.ffmpeg.global.avutil

  


  It will break when trying to get the 'grabber' :

  


  private void videoInfo(MultipartFile file) {
    try (FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(file.getInputStream())) { // on this line it will break :(
        grabber.start();
        long durationMs = grabber.getLengthInTime();
    } catch (FrameGrabber.Exception e) {
        throw new RuntimeException(e);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}


  


  This is my build.gradle :

  


  plugins {
    id 'java'
    id 'org.springframework.boot' version '2.7.9'
    id 'io.spring.dependency-management' version '1.0.15.RELEASE'
}

group = 'com.nob234'
version = '0.0.1-SNAPSHOT'

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
    compileOnly 'org.projectlombok:lombok'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    implementation 'org.springdoc:springdoc-openapi-ui:1.6.9'
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
    runtimeOnly 'org.postgresql:postgresql'
    // for logging
    implementation 'org.slf4j:slf4j-api:1.7.30'
    implementation 'org.slf4j:jcl-over-slf4j:1.7.30'
    implementation 'org.slf4j:log4j-over-slf4j:1.7.30'
    implementation 'ch.qos.logback:logback-classic:1.2.3'
    implementation 'org.bytedeco:javacv:1.5.8'
}

tasks.named('test') {
    useJUnitPlatform()
}


  


  This is my ffmpeg version :

  


  ffmpeg version 6.0-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
libavutil      58.  2.100 / 58.  2.100
libavcodec     60.  3.100 / 60.  3.100
libavformat    60.  3.100 / 60.  3.100
libavdevice    60.  1.100 / 60.  1.100
libavfilter     9.  3.100 /  9.  3.100
libswscale      7.  1.100 /  7.  1.100
libswresample   4. 10.100 /  4. 10.100
libpostproc    57.  1.100 / 57.  1.100


  


  Please keep in mind that I use Java 8 in this project and I hope this issue is reproducible. If you want more info please leave a comment.

  


• avcodec_find_decoder() can't find AV_CODEC_ID_WMAV2 even through CLI can parse WMAs on macOS ?

  3 octobre 2023, par grendell

  I am following the decode_audio.c example from FFmpeg, but I am unable to initialize a parser for AV_CODEC_ID_WMAV2.

  


  Test code :

  


  #include &#xA;#include <libavcodec></libavcodec>avcodec.h>&#xA;&#xA;int main() {&#xA;    // codec is found successfully&#xA;    const AVCodec * codec = avcodec_find_decoder(AV_CODEC_ID_WMAV2);&#xA;    if (!codec) {&#xA;        fprintf(stderr, "codec not found\n");&#xA;        return 1;&#xA;    }&#xA;&#xA;    // parser is always NULL&#xA;    AVCodecParserContext * parser = av_parser_init(codec->id);&#xA;    if (!parser) {&#xA;        fprintf(stderr, "parser not found\n");&#xA;        return 1;&#xA;    }&#xA;&#xA;    av_parser_close(parser);&#xA;    return 0;&#xA;}&#xA;

  


  Build commands :

  


  clang -c -I/opt/homebrew/Cellar/ffmpeg/6.0_1/include wma2mp3.c -o obj/wma2mp3.o
clang -L/opt/homebrew/Cellar/ffmpeg/6.0_1/lib -lavcodec obj/wma2mp3.o -o wma2mp3


  


  I'm surprised by the fact that the FFmpeg CLI can perform this operation on the same machine :

  


  % ffmpeg -i test.wma test.mp3
ffmpeg version 6.0 Copyright (c) 2000-2023 the FFmpeg developers
  built with Apple clang version 14.0.3 (clang-1403.0.22.14.1)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.0_1 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100
Guessed Channel Layout for Input Stream #0.0 : mono
Input #0, asf, from 'test.wma':
  Metadata:
    ToolName        : Windows Media Encoding Utility
    ToolVersion     : 8.00.00.0343
  Duration: 00:00:00.74, start: 0.000000, bitrate: 80 kb/s
  Stream #0:0: Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 1 channels, fltp, 48 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (wmav2 (native) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
Output #0, mp3, to 'test.mp3':
  Metadata:
    ToolName        : Windows Media Encoding Utility
    ToolVersion     : 8.00.00.0343
    TSSE            : Lavf60.3.100
  Stream #0:0: Audio: mp3, 44100 Hz, mono, fltp
    Metadata:
      encoder         : Lavc60.3.100 libmp3lame
[libmp3lame @ 0x130706320] Queue input is backward in timeed=N/A    
[mp3 @ 0x1307056e0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 15668 >= 14764
size=       8kB time=00:00:00.97 bitrate=  65.8kbits/s speed= 103x    
video:0kB audio:8kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 4.048112%


  


  I am using an Apple M1 machine running MacOS 13.5.2 (22G91).

  


  Is the CLI using a different mechanism than av_parser_parse2 to perform this conversion, and is there a better way to accomplish this via the C API ?