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• Reasons for "Segmentation fault (core dumped)" when using Python extension and FFmpeg

  24 août 2021, par Christian Vorhemus

  I want to write a Python C extension that includes a function convertVideo() that converts a video from one format to another making use of FFmpeg 3.4.8 (the libav* libaries). The code of the extension is at the end of the question. The extension compiles successfully but whenever I open Python and want to call it (using a simple Python wrapper code that I don't include here), I get

  


  Python 3.7.10 (default, May  2 2021, 18:28:10)
[GCC 9.1.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import myModule
>>> myModule.convert_video("/home/admin/video.h264", "/home/admin/video.mp4")
convert 0
convert 1
Format raw H.264 video, duration -9223372036854775808 us
convert 2
Segmentation fault (core dumped)


  


  The interesting thing is, I wrote a simple helper program test_convert.cc that calls convertVideo() like so

  


  #include 
#include 

int convertVideo(const char *in_filename, const char *out_filename);

int main() {
  int res = convertVideo("/home/admin/video.h264", "/home/admin/video.mp4");
  return 0;
}


  


  and I compiled this program making use of the shared library that Python generates when building the C extension like so

  


  gcc test_convert.cc /usr/lib/python3.7/site-packages/_myModule.cpython-37m-aarch64-linux-gnu.so -o test_convert


  


  And it works ! The output is

  


  root# ./test_convert
convert 0
convert 1
Format raw H.264 video, duration -9223372036854775808 us
convert 2
convert 3
convert 4
convert 5
convert 6
Output #0, mp4, to '/home/admin/video.mp4':
    Stream #0:0: Video: h264 (High), yuv420p(tv, bt470bg, progressive), 1280x720 [SAR 1:1 DAR 16:9], q=2-31
convert 7


  


  The extension code looks like this

  


  #include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 

extern "C"
{
#include "libavformat/avformat.h"
#include "libavutil/imgutils.h"
}

int convertVideo(const char *in_filename, const char *out_filename)
{
  // Input AVFormatContext and Output AVFormatContext
  AVFormatContext *input_format_context = avformat_alloc_context();
  AVPacket pkt;

  int ret, i;
  int frame_index = 0;
  printf("convert 0\n");
  av_register_all();
  printf("convert 1\n");
  // Input
  if ((ret = avformat_open_input(&input_format_context, in_filename, NULL,
                                 NULL)) < 0)
  {
    printf("Could not open input file.");
    return 1;
  }
  else
  {
    printf("Format %s, duration %lld us\n",
           input_format_context->iformat->long_name,
           input_format_context->duration);
  }
  printf("convert 2\n");
  if ((ret = avformat_find_stream_info(input_format_context, 0)) < 0)
  {
    printf("Failed to retrieve input stream information");
    return 1;
  }
  printf("convert 3\n");
  AVFormatContext *output_format_context = avformat_alloc_context();
  AVPacket packet;
  int stream_index = 0;
  int *streams_list = NULL;
  int number_of_streams = 0;
  int fragmented_mp4_options = 0;
  printf("convert 4\n");
  avformat_alloc_output_context2(&output_format_context, NULL, NULL,
                                 out_filename);
  if (!output_format_context)
  {
    fprintf(stderr, "Could not create output context\n");
    ret = AVERROR_UNKNOWN;
    return 1;
  }
  printf("convert 5\n");
  AVOutputFormat *fmt = av_guess_format(0, out_filename, 0);
  output_format_context->oformat = fmt;

  number_of_streams = input_format_context->nb_streams;
  streams_list =
      (int *)av_mallocz_array(number_of_streams, sizeof(*streams_list));

  if (!streams_list)
  {
    ret = AVERROR(ENOMEM);
    return 1;
  }
  for (i = 0; i < input_format_context->nb_streams; i++)
  {
    AVStream *out_stream;
    AVStream *in_stream = input_format_context->streams[i];
    AVCodecParameters *in_codecpar = in_stream->codecpar;
    if (in_codecpar->codec_type != AVMEDIA_TYPE_AUDIO &&
        in_codecpar->codec_type != AVMEDIA_TYPE_VIDEO &&
        in_codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE)
    {
      streams_list[i] = -1;
      continue;
    }
    streams_list[i] = stream_index++;

    out_stream = avformat_new_stream(output_format_context, NULL);
    if (!out_stream)
    {
      fprintf(stderr, "Failed allocating output stream\n");
      ret = AVERROR_UNKNOWN;
      return 1;
    }
    ret = avcodec_parameters_copy(out_stream->codecpar, in_codecpar);
    if (ret < 0)
    {
      fprintf(stderr, "Failed to copy codec parameters\n");
      return 1;
    }
  }
  printf("convert 6\n");
  av_dump_format(output_format_context, 0, out_filename, 1);
  if (!(output_format_context->oformat->flags & AVFMT_NOFILE))
  {
    ret = avio_open(&output_format_context->pb, out_filename, AVIO_FLAG_WRITE);
    if (ret < 0)
    {
      fprintf(stderr, "Could not open output file '%s'", out_filename);
      return 1;
    }
  }
  AVDictionary *opts = NULL;
  printf("convert 7\n");
  ret = avformat_write_header(output_format_context, &opts);
  if (ret < 0)
  {
    fprintf(stderr, "Error occurred when opening output file\n");
    return 1;
  }
  int n = 0;

  while (1)
  {
    AVStream *in_stream, *out_stream;
    ret = av_read_frame(input_format_context, &packet);
    if (ret < 0)
      break;
    in_stream = input_format_context->streams[packet.stream_index];
    if (packet.stream_index >= number_of_streams ||
        streams_list[packet.stream_index] < 0)
    {
      av_packet_unref(&packet);
      continue;
    }
    packet.stream_index = streams_list[packet.stream_index];

    out_stream = output_format_context->streams[packet.stream_index];

    out_stream->codec->time_base.num = 1;
    out_stream->codec->time_base.den = 30;

    packet.pts = n * 3000;
    packet.dts = n * 3000;
    packet.duration = 3000;

    packet.pos = -1;

    ret = av_interleaved_write_frame(output_format_context, &packet);
    if (ret < 0)
    {
      fprintf(stderr, "Error muxing packet\n");
      break;
    }
    av_packet_unref(&packet);
    n++;
  }

  av_write_trailer(output_format_context);
  avformat_close_input(&input_format_context);
  if (output_format_context &&
      !(output_format_context->oformat->flags & AVFMT_NOFILE))
    avio_closep(&output_format_context->pb);
  avformat_free_context(output_format_context);
  av_freep(&streams_list);
  if (ret < 0 && ret != AVERROR_EOF)
  {
    fprintf(stderr, "Error occurred\n");
    return 1;
  }
  return 0;
}
// PyMethodDef and other orchestration code is skipped


  


  What is the reason that the code works as expected in my test_convert but not within Python ?

  


• ffmpeg says "No JPEG data found in image" when reading image paths from Linux pipe

  18 septembre 2021, par user16945608

  I'm trying to convert a set of pictures into a video, and I want to read the file paths of the pictures from the pipe. The command I would like to run looks like this :

  


  find dir/*.JPG | sort | ffmpeg -f image2pipe -r 1 -vcodec mjpeg -s 6000x4000 -pix_fmt yuvj422p -i - -vcodec libx264 -s 1080x720 -r 20 -pix_fmt yuv420p out.mkv

  


  But I keep obtaining the No JPEG data found in image error. Here is the full log :

  


  Input #0, image2pipe, from 'pipe:':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: mjpeg, yuvj422p(bt470bg/unknown/unknown), 6000x4000, 1 fps, 1 tbr, 1 tbn, 1 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
[mjpeg @ 0x558e98cd7300] No JPEG data found in image
Error while decoding stream #0:0: Invalid data found when processing input
[swscaler @ 0x558e98ce9440] deprecated pixel format used, make sure you did set range correctly
[libx264 @ 0x558e98cdaac0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x558e98cdaac0] profile High, level 3.1, 4:2:0, 8-bit
[libx264 @ 0x558e98cdaac0] 264 - core 161 r3039 544c61f - H.264/MPEG-4 AVC codec - Copyleft
2003-2021 - http://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=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=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=20 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, matroska, to 'out.mkv':
  Metadata:
    encoder         : Lavf58.76.100
  Stream #0:0: Video: h264 (H264 / 0x34363248), yuv420p, 1080x720, q=2-31, 20 fps, 1k tbn
    Metadata:
      encoder         : Lavc58.134.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=    0 fps=0.0 q=0.0 Lsize=       1kB time=00:00:00.00 bitrate=N/A speed=   0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Conversion failed!


  


  The pictures are in the following format (with mediainfo) and the filenames are in the form DSC_1234.JPG :

  


  Format                                   : JPEG
Video
Format                                   : JPEG
Width                                    : 6 000 pixels
Height                                   : 4 000 pixels
Display aspect ratio                     : 3:2
Color space                              : YUV
Chroma subsampling                       : 4:2:2
Bit depth                                : 8 bits
Compression mode                         : Lossy


  


  Also, I would like to avoid using a solution without piping the paths (with -f image2 -i DSC_%04d.JPG for example). Do you have any idea what's happening ?

  


• FFmpeg's common filter "v360" missing

  26 septembre 2021, par Niklas E.

  I'm trying to convert a 180° fisheye video to a normal/regular video using the v360 filter of FFmpeg.

  


  This is the command I tried :
  
ffmpeg -i in.mp4 -vf "v360=input=fisheye:output=flat:iv_fov=180:v_fov=90" out.mp4

  


  But the output says clearly No such filter: 'v360', although v360 is a common filter listed in docs and other filters I used before worked just fine. I tried updating/reinstalling and looking for solutions, not fixing it.

  


  Why is the filter missing ? How can I debug this ? Should I doe the task using another program entirely ?

  


  Command output :

  


  ffmpeg version 4.2.4-1ubuntu0.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
  configuration: --prefix=/usr --extra-version=1ubuntu0.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42mp41
    creation_time   : 2021-09-11T14:18:33.000000Z
  Duration: 00:02:48.02, start: 0.000000, bitrate: 26056 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 2160x1080 [SAR 1:1 DAR 2:1], 25924 kb/s, 50 fps, 50 tbr, 50k tbn, 100 tbc (default)
    Metadata:
      creation_time   : 2021-09-11T14:18:33.000000Z
      handler_name    : Mainconcept MP4 Video Media Handler
      encoder         : AVC Coding
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
    Metadata:
      creation_time   : 2021-09-11T14:18:33.000000Z
      handler_name    : Mainconcept MP4 Sound Media Handler
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[AVFilterGraph @ 0x55ee57567340] No such filter: 'v360'
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #0:0
Conversion failed!