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• Making half an image transparent from the command line

  14 octobre 2016, par Alex Konetchy

  I don’t really know where to start with this one. I’m trying to do something that I thought would be relatively simple to accomplish with imagemagick, but I don’t know the exact command to start with. I need to draw a line through an image, and then make everything above the line transparent in the image, and make everything below the line, the orignal image. What would be the best way to accomplish this using imagemagick ?

  So what I’ve come up with for now is to crop the image, and then resize it to the original size, but with a transparent background. The command I use is this, but it always comes out black. I’m not understanding why.

  convert -background none -gravity south out.png -resize 400x200 -extent 400x400 result.png

  Thanks for all of the help !

• FFMPEG RGB Lossless conversion video

  29 août 2017, par DCDCDC

  I have been experiencing difficulty in finding many answers with FFMPEG documentation, forums and here.
  What I am trying to do is a compress a screen capture video but with just RGB data.
  The steps I am currently taking are ;

  ffmpeg -f avfoundation -pix_fmt 0rgb -r "30" -i "1" -vcodec libx264rgb -pix_fmt rgb24 -crf 0 -t 25 -q 0 -y ~/Desktop/RGB.mkv 
  
  
  
  south-58-45:~ danielcarter$ ffmpeg -f avfoundation -pix_fmt 0rgb -r "30" -i "1" -vcodec libx264rgb -pix_fmt rgb24 -crf 0 -t 170 -q 0 -y -v info ~/Desktop/output.mkv
  
  ffmpeg version 3.3 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with Apple LLVM version 8.1.0 (clang-802.0.41)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libavresample   3.  5.  0 /  3.  5.  0
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  [avfoundation @ 0x7fc39d004c00] Stream #0: not enough frames to estimate rate; consider increasing probesize
  
  Input #0, avfoundation, from '1':
  
    Duration: N/A, start: 175270.249500, bitrate: N/A
  
      Stream #0:0: Video: rawvideo ([0]RGB / 0x42475200), 0rgb, 1440x900, 1000k tbr, 1000k tbn, 1000k tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264rgb))
  
  Press [q] to stop, [?] for help
  
  [libx264rgb @ 0x7fc39d13ea00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  [libx264rgb @ 0x7fc39d13ea00] profile High 4:4:4 Predictive, level 4.0, 4:4:4 8-bit
  
  [libx264rgb @ 0x7fc39d13ea00] 264 - core 148 r2748 97eaef2 - H.264/MPEG-4 AVC codec - Copyleft 2003-2016 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=0 mixed_ref=1 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc=cqp mbtree=0 qp=0
  
  Output #0, matroska, to '/Users/danielcarter/Desktop/output.mkv':
  
    Metadata:
  
      encoder         : Lavf57.71.100
  
      Stream #0:0: Video: h264 (libx264rgb) (H264 / 0x34363248), rgb24, 1440x900, q=-1--1, 30 fps, 1k tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc57.89.100 libx264rgb
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  frame= 5100 fps= 30 q=-1.0 Lsize=   12167kB time=00:02:49.96 bitrate= 586.4kbits/s speed=0.999x    
  
  video:12134kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.267659%
  
  [libx264rgb @ 0x7fc39d13ea00] frame I:21    Avg QP: 0.00  size:430796
  
  [libx264rgb @ 0x7fc39d13ea00] frame P:5079  Avg QP: 0.00  size:   665
  
  [libx264rgb @ 0x7fc39d13ea00] mb I  I16..4: 61.3%  0.0% 38.7%
  
  [libx264rgb @ 0x7fc39d13ea00] mb P  I16..4:  0.1%  0.0%  0.0%  P16..4:  0.0%  0.0%  0.0%  0.0%  0.0%    skip:99.9%
  
  [libx264rgb @ 0x7fc39d13ea00] 8x8 transform intra:0.0% inter:11.2%
  
  [libx264rgb @ 0x7fc39d13ea00] coded y,u,v intra: 48.0% 31.6% 29.0% inter: 0.0% 0.0% 0.0%
  
  [libx264rgb @ 0x7fc39d13ea00] i16 v,h,dc,p: 76% 22%  2%  0%
  
  [libx264rgb @ 0x7fc39d13ea00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 46% 35%  7%  2%  2%  1%  1%  1%  3%
  
  [libx264rgb @ 0x7fc39d13ea00] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264rgb @ 0x7fc39d13ea00] ref P L0: 83.1%  6.4%  5.3%  5.2%
  
  [libx264rgb @ 0x7fc39d13ea00] kb/s:584.71

  This captures the screen on my mac. To the best of my knowledge, this creates a lossless file and I have compared screen shots that confirm this.
  The next step is where I think I have an issue.
  Because I want to run the compression on raw RGB data I need to convert the MKV to an RGB file ;

  ffmpeg -i ~/Desktop/RGB.mkv -c:v rawvideo -pix_fmt rgb24 -crf 0 -ss 00:00:03 -to 00:02:01 -q 0 -y ~/Desktop/out.rgb
  
  
  
  south-58-45:~ danielcarter$ ffmpeg -i ~/Desktop/output.mkv -c:v rawvideo -pix_fmt rgb24 -crf 0 -ss 00:00:03 -to 00:02:01 -q 0 -y ~/Desktop/out.rgb
  
  ffmpeg version 3.3 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with Apple LLVM version 8.1.0 (clang-802.0.41)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libavresample   3.  5.  0 /  3.  5.  0
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  Input #0, matroska,webm, from '/Users/danielcarter/Desktop/output.mkv':
  
    Metadata:
  
      ENCODER         : Lavf57.71.100
  
    Duration: 00:02:50.00, start: 0.000000, bitrate: 586 kb/s
  
      Stream #0:0: Video: h264 (High 4:4:4 Predictive), gbrp(tv, gbr/unknown/unknown, progressive), 1440x900, 30 fps, 30 tbr, 1k tbn, 60 tbc (default)
  
      Metadata:
  
        ENCODER         : Lavc57.89.100 libx264rgb
  
        DURATION        : 00:02:50.000000000
  
  Codec AVOption crf (Select the quality for constant quality mode) specified for output file #0 (/Users/danielcarter/Desktop/out.rgb) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
  
  Press [q] to stop, [?] for help
  
  Output #0, rawvideo, to '/Users/danielcarter/Desktop/out.rgb':
  
    Metadata:
  
      encoder         : Lavf57.71.100
  
      Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 1440x900, q=2-31, 933120 kb/s, 30 fps, 30 tbn, 30 tbc (default)
  
      Metadata:
  
        DURATION        : 00:02:50.000000000
  
        encoder         : Lavc57.89.100 rawvideo
  
  frame= 3540 fps=111 q=-0.0 Lsize=13440938kB time=00:01:58.00 bitrate=933120.0kbits/s speed=3.68x    
  
  video:13440938kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

  Once I have this I can then compress and decompress successfully. I then get a working file to play back using ;

  ffmpeg -f rawvideo -vcodec rawvideo -s 1440x900 -r 30 -pix_fmt rgb24 -i ~/Desktop/out.rgb -c:v libx264rgb -pix_fmt rgb24 -x264opts keyint=300:min-keyint=300:no-scenecut -y -crf 0 ~/Desktop/rgbplay.mkv
  
  
  
  south-58-45:~ danielcarter$ ffmpeg -f rawvideo -vcodec rawvideo -s 1440x900 -r 30 -pix_fmt rgb24 -i ~/Desktop/out.rgb -c:v libx264rgb -pix_fmt rgb24 -x264opts keyint=300:min-keyint=300:no-scenecut -y -crf 0 ~/Desktop/rgbplay.mkv
  
  ffmpeg version 3.3 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with Apple LLVM version 8.1.0 (clang-802.0.41)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libavresample   3.  5.  0 /  3.  5.  0
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  [rawvideo @ 0x7fb1f9002600] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, rawvideo, from '/Users/danielcarter/Desktop/out.rgb':
  
    Duration: 00:01:58.00, start: 0.000000, bitrate: 933120 kb/s
  
      Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 1440x900, 933120 kb/s, 30 tbr, 30 tbn, 30 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264rgb))
  
  Press [q] to stop, [?] for help
  
  [libx264rgb @ 0x7fb1f9010c00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  [libx264rgb @ 0x7fb1f9010c00] profile High 4:4:4 Predictive, level 4.0, 4:4:4 8-bit
  
  [libx264rgb @ 0x7fb1f9010c00] 264 - core 148 r2748 97eaef2 - H.264/MPEG-4 AVC codec - Copyleft 2003-2016 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=0 mixed_ref=1 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=2 keyint=300 keyint_min=151 scenecut=0 intra_refresh=0 rc=cqp mbtree=0 qp=0
  
  Output #0, matroska, to '/Users/danielcarter/Desktop/rgbplay.mkv':
  
    Metadata:
  
      encoder         : Lavf57.71.100
  
      Stream #0:0: Video: h264 (libx264rgb) (H264 / 0x34363248), rgb24, 1440x900, q=-1--1, 30 fps, 1k tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc57.89.100 libx264rgb
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  frame= 3540 fps= 64 q=-1.0 Lsize=    8319kB time=00:01:57.96 bitrate= 577.7kbits/s speed=2.13x    
  
  video:8297kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.273154%
  
  [libx264rgb @ 0x7fb1f9010c00] frame I:12    Avg QP: 0.00  size:437670
  
  [libx264rgb @ 0x7fb1f9010c00] frame P:3528  Avg QP: 0.00  size:   919
  
  [libx264rgb @ 0x7fb1f9010c00] mb I  I16..4: 61.9%  0.0% 38.1%
  
  [libx264rgb @ 0x7fb1f9010c00] mb P  I16..4:  0.1%  0.0%  0.0%  P16..4:  0.0%  0.0%  0.0%  0.0%  0.0%    skip:99.8%
  
  [libx264rgb @ 0x7fb1f9010c00] 8x8 transform intra:0.0% inter:15.1%
  
  [libx264rgb @ 0x7fb1f9010c00] coded y,u,v intra: 49.7% 36.5% 33.7% inter: 0.0% 0.0% 0.0%
  
  [libx264rgb @ 0x7fb1f9010c00] i16 v,h,dc,p: 73% 25%  1%  0%
  
  [libx264rgb @ 0x7fb1f9010c00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 45% 36%  7%  2%  2%  2%  2%  1%  3%
  
  [libx264rgb @ 0x7fb1f9010c00] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264rgb @ 0x7fb1f9010c00] ref P L0: 81.3%  7.7%  6.7%  4.3%
  
  [libx264rgb @ 0x7fb1f9010c00] kb/s:575.96

  But here I have pixel variance. My guess is there is a RGB-YUV-RGB conversion happening somewhere but I am not smart enough to work out where.
  If any of you can help I would forever grateful.

  Here is a picture of the two stills side by side that shows the differences ;

  pixel difference

  If you need anything more I can post it also.
  Cheers,
  DC

• How to watch or download periscope live streams from start ?

  10 septembre 2019, par Sanchit

  I am trying to figure how watch/download a periscope livestream from it’s starting point. The app doesn’t let go back more than 2 minutes so I tried downloading as someone told me it downloads from beginning but it didn’t. It started from the current time.

  I tried running :

  youtube-dl https://www.pscp.tv/w/b_7KWDFyYVFaeFhCTXhaanp8MXluS09Sd05QRFZ4Uuj5klcOLvuiNqQPC2PcorcMlZOwD3uZyIP7o-UXVYNi

  I get

  https://prod-fastly-ap-south-1.video.periscope.tv/Transcoding/v1/-/chunk_1563350917969725824_36817_a.ts?type=live
  
  
  
  https://prod-fastly-ap-south-1.video.periscope.tv/Transcoding/v1/-/chunk_1563350926386273572_36818_a.ts?type=live