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• How to record desktop while on x2go session via a command line tool ?

  4 décembre 2017, par haragei

  the Goal :
  I am trying to record a specific X display on a remote server with a command line tool.

  the Problem :
  The output file contains a pure black video stream for the whole duration of the recording.

  My Approach :
  I am connecting to a remote server via x2go. The Server runs Ubuntu 16.04.2 with Xfce Desktop Environment. The Display I try to record is :50 (which gets created when I connect to the x2go server). I can control the remote server totally fine through x2go.

  My commands for recording via ffmpeg (or avconv/recordmydesktop, which use ffmpeg underneath) all look more or less the same and are like this :
  ffmpeg -f x11grab -r 25 -s 1854x1176 -i :50.0 -c:v libx264 screencast.mkv

  Sample output :

  user@machine:~/$ ffmpeg -f x11grab -r 25 -s 1854x1176 -i :50.0+0,0 -c:v libx264 -vb 4000k -an screencast.mkv
  
  ffmpeg version N-86766-g264f6c6 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
  
    configuration: --prefix=/home/user/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/user/ffmpeg_build/include --extra-ldflags=-L/home/user/ffmpeg_build/lib --bindir=/home/user/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree
  
    libavutil      55. 67.100 / 55. 67.100
  
    libavcodec     57.100.104 / 57.100.104
  
    libavformat    57. 75.100 / 57. 75.100
  
    libavdevice    57.  7.100 / 57.  7.100
  
    libavfilter     6. 95.100 /  6. 95.100
  
    libswscale      4.  7.101 /  4.  7.101
  
    libswresample   2.  8.100 /  2.  8.100
  
    libpostproc    54.  6.100 / 54.  6.100
  
  [x11grab @ 0x1fd9b40] XFixes not available, cannot draw the mouse.
  
  [x11grab @ 0x1fd9b40] Stream #0: not enough frames to estimate rate; consider increasing probesize
  
  Input #0, x11grab, from ':50.0+0,0':
  
    Duration: N/A, start: 1500041497.684675, bitrate: N/A
  
      Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1854x1176, 25 fps, 1000k tbr, 1000k tbn, 1000k tbc
  
  File 'screencast.mkv' already exists. Overwrite ? [y/N] y
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x1fe3040] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x1fe3040] profile High 4:4:4 Predictive, level 4.2, 4:4:4 8-bit
  
  [libx264 @ 0x1fe3040] 264 - core 148 r2643 5c65704 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - 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=4 threads=12 lookahead_threads=2 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=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=abr mbtree=1 bitrate=4000 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, matroska, to 'screencast.mkv':
  
    Metadata:
  
      encoder         : Lavf57.75.100
  
      Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv444p, 1854x1176, q=-1--1, 4000 kb/s, 25 fps, 1k tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc57.100.104 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/4000000 buffer size: 0 vbv_delay: -1
  
  [swscaler @ 0x1fe94e0] Warning: data is not aligned! This can lead to a speedloss
  
  frame=  179 fps= 36 q=-1.0 Lsize=      16kB time=00:00:07.04 bitrate=  18.8kbits/s speed=1.43x    
  
  video:14kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 12.869934%
  
  [libx264 @ 0x1fe3040] frame I:1     Avg QP: 6.00  size:   518
  
  [libx264 @ 0x1fe3040] frame P:45    Avg QP: 0.44  size:    81
  
  [libx264 @ 0x1fe3040] frame B:133   Avg QP: 0.94  size:    73
  
  [libx264 @ 0x1fe3040] consecutive B-frames:  0.6%  1.1%  0.0% 98.3%
  
  [libx264 @ 0x1fe3040] mb I  I16..4:  0.0% 100.0%  0.0%
  
  [libx264 @ 0x1fe3040] mb P  I16..4:  0.0%  0.0%  0.0%  P16..4:  0.0%  0.0%  0.0%  0.0%  0.0%    skip:100.0%
  
  [libx264 @ 0x1fe3040] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  0.0%  0.0%  0.0%  direct: 0.0%  skip:100.0%
  
  [libx264 @ 0x1fe3040] final ratefactor: -23.85
  
  [libx264 @ 0x1fe3040] 8x8 transform intra:100.0%
  
  [libx264 @ 0x1fe3040] coded y,u,v intra: 0.0% 0.0% 0.0% inter: 0.0% 0.0% 0.0%
  
  [libx264 @ 0x1fe3040] i16 v,h,dc,p:  0%  0% 100%  0%
  
  [libx264 @ 0x1fe3040] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  0%  0% 100%  0%  0%  0%  0%  0%  0%
  
  [libx264 @ 0x1fe3040] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 0x1fe3040] kb/s:15.56

  Using : Ubuntu 16.04.2 LTS

  I have successfully accomplished to capture the display :50 with "simplescreenrecorder", but that tool has no command line interface. It uses ffmpeg also, so it somehow should be possible to caputure the display but I can´t get it to work properly.

• avcodec/nvenc : Declare support for P016

  25 février 2018, par Philip Langdale

  avcodec/nvenc : Declare support for P016
  nvenc doesn't support P016, but we have two problems today :
  1) We declare support for YUV444P16 which nvenc also doesn't support.
  
     We do this because it's the only pix_fmt we have that can
  
     approximate nvenc's internal format that is YUV444P10 with data in
  
     MSBs instead of LSBs. Because the declared format is a 16bit one,
  
     it will be preferrentially chosen when encoding >10bit content,
  
     but that content will normally be YUV420P12 or P016 which should
  
     get mapped to P010 and not YUV444P10.
  2) Transcoding P016 content with nvenc should be possible in a pure
  
     hardware pipeline, and that can't be done if nvenc doesn't say it
  
     accepts P016. By mapping it to P010, we can use it, albeit with
  
     truncation. I have established that swscale doesn't know how to
  
     dither to 10bits so we'd get truncation anyway, even if we tried
  
     to do this 'properly'.
  

  • [DH] libavcodec/nvenc.c
  • [DH] libavcodec/version.h

• Audacity vocal removal failed when ffmpeg-conversion was involved

  10 mars 2018, par fyang

  I downloaded some songs coded with FLAC, and Audacity could remove the vocals quite well.

  When I downloaded songs coded with ALAC, I must use ffmpeg to convert them to some other forms because Audacity didn’t recognise .m4a files.

  I used the command ffmpeg -i "song 01.m4a" -f flac "song 01.flac". Now Audacity could load the song, but its vocal removal failed to remove the vocals.

  I tried again with this command in order to be precise, ffmpeg -i "song 01.m4a" -af "pan=stereo|c0=c0|c1=c1" -f flac "song 01.flac", and vocal removal did not work either.

  I tried to do it manually by splitting, inverting and changing both channels to mono, but the vocals were still there.

  I think the problem lies with the ffmpeg conversion step. Is there any fix ? Thanks !

  Below is the result of the conversion :

  ffmpeg -i "song 01.m4a" -af "pan=stereo|c0=c0|c1=c1" -f flac "song 01.flac"
  
  ffmpeg version N-90143-gb6652f5100 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 7.3.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libmfx --enable-amf --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth
  
    libavutil      56.  7.101 / 56.  7.101
  
    libavcodec     58. 12.102 / 58. 12.102
  
    libavformat    58.  9.100 / 58.  9.100
  
    libavdevice    58.  2.100 / 58.  2.100
  
    libavfilter     7. 12.100 /  7. 12.100
  
    libswscale      5.  0.101 /  5.  0.101
  
    libswresample   3.  0.101 /  3.  0.101
  
    libpostproc    55.  0.100 / 55.  0.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0000019f2b258000] stream 0, timescale not set
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'song 01.m4a':
  
    Metadata:
  
      major_brand     : M4A
  
      minor_version   : 0
  
      compatible_brands: M4A mp42isom
  
      creation_time   : 2009-12-27T00:15:23.000000Z
  
      track           : 1/10
  
      genre           : 
  
      album           : 
  
      artist          : 
  
      comment         : ExactAudioCopy v0.95b4
  
      DISCID          : 
  
      iTunNORM        :  00000F32 00000E1D 0000547D 00005B93 0006C3CA 0006C43E 00007FF8 00007FFF 00058227 0003593B
  
      title           : song 01
  
      encoder         : iTunes 9.0.2.25
  
      date            : 2005
  
      album_artist    : 
  
      lyrics          : 
  
    Duration: 00:08:10.84, start: 0.000000, bitrate: 921 kb/s
  
      Stream #0:0(und): Audio: alac (alac / 0x63616C61), 44100 Hz, stereo, s16p, 920 kb/s (default)
  
      Metadata:
  
        creation_time   : 2009-12-27T00:15:23.000000Z
  
      Stream #0:1: Video: mjpeg, yuvj444p(pc, bt470bg/unknown/unknown), 300x300 [SAR 100:100 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (alac (native) -> flac (native))
  
  Press [q] to stop, [?] for help
  
  [Parsed_pan_0 @ 0000019f2b2a6fc0] Pure channel mapping detected: 0 1
  
  Output #0, flac, to 'song 01.flac':
  
    Metadata:
  
      major_brand     : M4A
  
      minor_version   : 0
  
      compatible_brands: M4A mp42isom
  
      lyrics          : 
  
      TRACKNUMBER     : 1/10
  
      genre           : 
  
      album           : 
  
      artist          : 
  
      DESCRIPTION     : ExactAudioCopy v0.95b4
  
      DISCID          : 
  
      iTunNORM        :  00000F32 00000E1D 0000547D 00005B93 0006C3CA 0006C43E 00007FF8 00007FFF 00058227 0003593B
  
      title           : song 01
  
      ALBUMARTIST     : 
  
      date            : 2005
  
      encoder         : Lavf58.9.100
  
      Stream #0:0(und): Audio: flac, 44100 Hz, stereo, s16, 128 kb/s (default)
  
      Metadata:
  
        creation_time   : 2009-12-27T00:15:23.000000Z
  
        encoder         : Lavc58.12.102 flac
  
  size=   54518kB time=00:08:10.84 bitrate= 909.9kbits/s speed=  35x
  
  video:0kB audio:54508kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.018294%