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• MLT query video_codecs not listing libx264

  7 juillet 2020, par Terryn94

  Querying video codecs does not list libx264 as an available codec

  


  [terry@localhost ~]$ melt -query video_codecs | grep 264
  - h264_nvenc
  - h264_v4l2m2m
  - h264_vaapi
  - nvenc_h264
  - h264
  - h264_cuvid


  


  But I can use it in a command such as :

  


  melt avformat:DarkStar.webm -consumer avformat:output.mp4 acodec=aac vcodec=libx264


  


  and it works successfully.
This is causing a problem with kdenlive. When selecting Render and choosing the format MP4 - the dominating format (H264/AAC) the render option is disabled with the error Unsupported video codec : libx264.

  


  kdenlive checks the profile codec against the list obtained from MLT using :

  


  Mlt::Properties vcodecs(mlt_properties(consumer->get_data("vcodec")));


  


  which seems to get the same list as query video_codecs.

  


  For info here is what ffmpeg says about the codecs :

  


  [terry@localhost ~]$ ffmpeg -codecs | grep 264
ffmpeg version 4.3 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.0 (PCLinuxOS 9.3.0-1pclos2020)
  configuration: --prefix=/usr --enable-shared --enable-pic --libdir=/usr/lib64 --shlibdir=/usr/lib64 --incdir=/usr/include --extra-cflags=-I/usr/include/nvenc --disable-stripping --enable-postproc --enable-gpl --enable-pthreads --enable-libtheora --enable-libvorbis --disable-encoder=vorbis --enable-libvpx --enable-runtime-cpudetect --enable-libdc1394 --enable-librtmp --enable-libspeex --enable-libfreetype --enable-libgsm --enable-libcelt --enable-libopus --enable-libopencv --enable-libopenjpeg --enable-libtwolame --enable-libxavs --enable-frei0r --enable-libmodplug --enable-libass --enable-gnutls --enable-libcdio --enable-libpulse --enable-libv4l2 --enable-avresample --enable-opencl --enable-libmp3lame --enable-libaom --enable-sndio --enable-libdav1d --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-version3 --enable-libx264 --enable-libx265 --enable-libvo-amrwbenc --enable-libxvid --enable-decoder=atrac3 --enable-decoder=atrac3p --enable-libwebp --enable-libfdk-aac --enable-nonfree --enable-cuda --enable-cuvid --enable-nvenc --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
 DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (decoders: h264 h264_v4l2m2m h264_cuvid ) (encoders: libx264 libx264rgb h264_nvenc h264_v4l2m2m h264_vaapi nvenc nvenc_h264 )


  


  Software versions :

  


  mlt-6.20.0

  


  ffmpeg-4.3

  


  x264-1.157.20190309

  


• ffmpeg stops capturing whole hour of HTTP stream after some time

  7 juillet 2020, par CompuChip

  First of all, sorry if I'm using the wrong terminology. I've been playing around with nginx and I'm still a bit confused about RTMP and HLS and other acronyms.

  


  I've managed to setup OBS to stream to an nginx server, which takes the RTMP stream and chops it into pieces for HLS. Here's the relevant part of the nginx configuration file.

  


  rtmp {
    server {
        listen 1935;
        chunk_size 4000;
        ping 30s;
        deny play all;

        application live {
            live on;
            hls on;
            hls_nested on; # Create a new folder for each stream
            hls_path /mnt/hls/live;
            hls_fragment 3s;
            hls_fragment_naming timestamp;
            hls_playlist_length 60s;
        }
    }
}

http {
    server {
        listen 81 ssl;

        #creates the http-location for our full-resolution (desktop) HLS stream - "http://localhost:8080/live/test/index.m3u8"
        location /live {
            # Elided caching and CORS for brevity

            alias /mnt/hls/live;
            add_header Cache-Control no-cache;
            index index.m3u8;
        }
    }
}


  


  This works well, I can view the stream in VLC or on a website and it looks smooth. Now I wanted to add some logging : I'd like to write full hours (starting at xx:00:00 and ending at xx:59:59) to a file named log_yyyymmdd_hh.mp4, e.g. log_20200707_18.mp4 for the files of 7 July 2020, 18:00 - 19:00 hrs. So I've set up an hourly cron job with the following ffmpeg command :

  


  ffmpeg -i https://stream.example.com:81/live/<streamkey> -preset veryfast -maxrate 2000k \&#xA;    -bufsize 2000k -g 60 -t 3600 -y /var/video/log/$(date &#x2B;\%Y\%m\%d_\%H00).mp4 >/dev/null 2>&amp;1&#xA;</streamkey>

  


  At first this seemed to work well, so I left it running happily for about 24 hours. When I checked, most of my hourly files were small ( 100MB) files of about 10 to 15 minutes long. It seems like any small delay in the stream will cause ffmpeg to stop writing to the file. I suspect such hiccups may for example be caused by an OBS plugin and I'll need to look into that, but I would prefer that ffmpeg will retry for some time before giving up. What arguments should I be passing to ffmpeg to make it not break when the stream is down for, say, up to a second every now and then ?.

  


  When I view back the HLS files there don't seem to be any noticeable gaps, so eventually all the data arrives. I went for the crontab solution with ffmpeg because when recording from nginx I could not figure out how to start recording at the start of the whole hour.

  


• av_hwdevice_iterate_types returns an empty list

  9 juillet 2020, par Ruslan Ablyazov

  I used an example https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/hw_decode.c

  


  The av_hwdevice_iterate_types function returns an empty list. What could be the reason ?

  


  And avcodec_find_decoder_by_name("h264_cuvid") returns NULL.

  


  FFmpeg version :

  


  ffmpeg version 4.3 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --enable-gpl --enable-ladspa --enable-libpulse --enable-libsoxr --enable-libspeex --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-nonfree --disable-ffplay --enable-libxvid --enable-cuda --enable-cuda-nvcc --enable-cuvid --enable-nvenc --enable-nonfree --enable-libnpp --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100


  


  The command ffmpeg -c:v h264_cuvid -i 7.mp4 71.mp4 outputs :

  


  ...
Stream mapping:
Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (libx264))
....


  


  And it works.

  


  The command ffmpeg-hwaccel cuda-i 7.mp4 71.mp4 outputs :

  


  ...
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
....


  


  The command ffmpeg -codecs outputs :

  


   ...
 DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (decoders: h264 h264_v4l2m2m h264_cuvid ) (encoders: libx264 libx264rgb h264_nvenc h264_v4l2m2m nvenc nvenc_h264 )
 D.VIL. hap                  Vidvox Hap
 DEV.L. hevc                 H.265 / HEVC (High Efficiency Video Coding) (decoders: hevc hevc_v4l2m2m hevc_cuvid ) (encoders: libx265 nvenc_hevc hevc_nvenc hevc_v4l2m2m )
 ...