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• Reduce latency in ffmpeg snapshot

  3 décembre 2015, par Acorian0

  I have a latency problem with FFMPEG.

  I have a streaming server running and I occasionally need to take multiple snapshots over a period of time (in the example below, 5s), and then examine the snapshots taken. Time is critical.

  With this command I take 25 frames per second over 5 seconds, meaning I will have 125 snapshots in my folder.

  ffmpeg.exe -ss 0.05 -re -i udp://239.255.0.xx:xxxx -ss 0 -vf fps=25 -to 5 -y \Test\%5d.jpg

  The -vf fps is forcing the 25 frames per second even if the server can’t provide them.

  The problem is that -ss 0.05 is not doing its job. It is supposed to delay the initial snapshot for 50 milliseconds but FFMPEG takes around 200ms to "start" the service on itself :/. This means the first snapshot is taken after around 200ms after I called the service. (200ms is way too big of a latency for my purpose... I can survive with 100ms)

  How can I force FFMPEG to start taking snapshots earlier ? Or is there a way to get snapshots, let’s say, from the buffer (e.g. start taking snapshots 150ms in the past) ?

  PS : Changing the -ss from 0.05 to 0.00 is not doing anything, I can only see the -ss doing something if the value is bigger than 0.2/0.25. Another thing, using a newer version of FFMPEG is by now impossible

  Sample OUTPUT :

  ffmpeg version 2.4.5 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Dec 30 2014 14:53:50 with gcc 4.9.2 (GCC)
  
    configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32thread
  
  s --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-icon
  
  v --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable
  
  -libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencor
  
  e-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-l
  
  ibschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-li
  
  bvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-l
  
  ibwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --ena
  
  ble-lzma --enable-decklink --enable-zlib
  
    libavutil      54.  7.100 / 54.  7.100
  
    libavcodec     56.  1.100 / 56.  1.100
  
    libavformat    56.  4.101 / 56.  4.101
  
    libavdevice    56.  0.100 / 56.  0.100
  
    libavfilter     5.  1.100 /  5.  1.100
  
    libswscale      3.  0.100 /  3.  0.100
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  0.100 / 53.  0.100
  
  [mpeg2video @ 01d77120] Invalid frame dimensions 0x0.
  
  Input #0, mpegts, from 'udp://239.255.0.14:5014':
  
    Duration: N/A, start: 159.051978, bitrate: 105241 kb/s
  
    Program 1
  
      Metadata:
  
        service_name    : Service01
  
        service_provider: FFmpeg
  
      Stream #0:0[0x100]: Video: mpeg1video ([2][0][0][0] / 0x0002), yuv420p(tv), 1920x1080 [SAR 1:1 D
  
  AR 16:9], 104857 kb/s, 50 tbr, 90k tbn, 50 tbc
  
      Stream #0:1[0x101]: Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16p, 384 kb/s
  
  [swscaler @ 01d70060] deprecated pixel format used, make sure you did set range correctly
  
  Output #0, image2, to 'C:\Test\%5d.jpg':
  
    Metadata:
  
      encoder         : Lavf56.4.101
  
      Stream #0:0: Video: mjpeg, yuvj420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25
  
  tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc56.1.100 mjpeg
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mpeg1video (native) -> mjpeg (native))
  
  Press [q] to stop, [?] for help
  
  frame=  125 fps= 25 q=24.8 Lsize=N/A time=00:00:05.00 bitrate=N/A dup=1 drop=0
  
  video:9710kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

• Streaming video written using FFmpeg (C# using AutoGen) sends multiple data requests

  26 juin 2016, par williamtroup

  I’ve written a video generator that rights a video in h264 format (mp4). When I stream the video from my azure service, i’m seeing the following network traffic :

  

  The AVCodecContext layout I’m using is as follows :

  AVCodec* videoCodec = ffmpeg.avcodec_find_encoder(AVCodecID.AV_CODEC_ID_H264)
  
  AVCodecContext* videoCodecContext = ffmpeg.avcodec_alloc_context3(videoCodec);
  
  videoCodecContext->bit_rate = 400000;
  
  videoCodecContext->width = 1280;
  
  videoCodecContext->height = 720;
  
  videoCodecContext->gop_size = 12;
  
  videoCodecContext->max_b_frames = 1;
  
  videoCodecContext->pix_fmt = videoCodec->pix_fmts[0];
  
  videoCodecContext->codec_id = videoCodec->id;
  
  videoCodecContext->codec_type = videoCodec->type;
  
  videoCodecContext->time_base = new AVRational
  
  {
  
      num = 1,
  
      den = 30
  
  };
  
  
  
  ffmpeg.av_opt_set(videoCodecContext->priv_data, "preset", "ultrafast");

  I cannot figure out how to solve this problem. Videos generating using Windows Movie Maker stream perfectly.

  Also, this appears to only happening in Google Chrome.

• AWS MediaConvert generating double length video

  1er mai 2024, par user1hjgjhgjhggjhg

  I am new to aws media convert. I am trying to convert the video but the final output video becomes double the length from the original one. for example if I have a video 30 seconds long, it will create 60 seconds long final video. Below is my son.

  


  {
  "Queue": "arn:aws:mediaconvert:us-west-2:730335xxxxx:queues/Default",
  "UserMetadata": {},
  "Role": "arn:aws:iam::73033541xxxx:role/service-role/MediaConvert_Default_Role",
  "Settings": {
    "TimecodeConfig": {
      "Source": "ZEROBASED"
    },
    "OutputGroups": [
      {
        "Name": "DASH ISO",
        "Outputs": [
          {
            "ContainerSettings": {
              "Container": "MPD"
            },
            "VideoDescription": {
              "CodecSettings": {
                "Codec": "H_264",
                "H264Settings": {
                  "MaxBitrate": 3500000,
                  "RateControlMode": "QVBR",
                  "SceneChangeDetect": "TRANSITION_DETECTION"
                }
              }
            },
            "NameModifier": "_output1"
          }
        ],
        "OutputGroupSettings": {
          "Type": "DASH_ISO_GROUP_SETTINGS",
          "DashIsoGroupSettings": {
            "SegmentLength": 30,
            "Destination": "s3://tutorial/video/",
            "FragmentLength": 2,
            "SegmentControl": "SINGLE_FILE"
          }
        }
      }
    ],
    "FollowSource": 1,
    "Inputs": [
      {
        "AudioSelectors": {
          "Audio Selector 1": {
            "DefaultSelection": "DEFAULT"
          }
        },
        "VideoSelector": {},
        "TimecodeSource": "ZEROBASED",
        "FileInput": "s3://tutorial/video/11 - video.mp4"
      }
    ]
  },
  "BillingTagsSource": "JOB",
  "AccelerationSettings": {
    "Mode": "DISABLED"
  },
  "StatusUpdateInterval": "SECONDS_60",
  "Priority": 0
}


  


  Please help