[FFmpeg-trac] #8905(undetermined:new): how to encode .flv with alpha channel?

[FFmpeg]

#8905: how to encode .flv with alpha channel?
-------------------------------------+-------------------------------------
             Reporter:  babsjgs      |                     Type:  task
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:  alpha        |               Blocked By:
  channel, alpha, flash, flv         |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Hello, I am trying to make a '''.flv video with alpha channel''', but the
 BG keeps coming out black.
 I was able to get a transparent background with the .webv format, but the
 machine I will be using this file is very weird and only reads .flv files.

 Do I need to add some special code on the "extra parameters..." box to
 achieve a transparent BG?

 Build: ffmpeg-20180522-fe84f70-win64-static

 From: quicktime .mov animation codec with alpha to .flv with alpha.

 This is the log:

 ----


 starting ffe job on 2020-09-22 @ 23:05:18.941
 command-line:
 D:\Users\Babs\Desktop\FFMPEG\ffmpeg-20180522-fe84f70-win64-static\bin\ffmpeg.exe
 -i "D:\Users\Babs\Desktop\CA00666_Multitaction video price oil 2.mov"
 -vcodec flv   -an  -b:v 4000k -r 30
 "D:\Users\Babs\Desktop\FFMPEG\teste4.flv"

 ffmpeg version N-91146-gfe84f70819 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-libaom --enable-libmfx
 --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-
 nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
   libavutil      56. 18.102 / 56. 18.102
   libavcodec     58. 19.102 / 58. 19.102
   libavformat    58. 16.100 / 58. 16.100
   libavdevice    58.  4.100 / 58.  4.100
   libavfilter     7. 24.100 /  7. 24.100
   libswscale      5.  2.100 /  5.  2.100
   libswresample   3.  2.100 /  3.  2.100
   libpostproc    55.  2.100 / 55.  2.100
 [mov,mp4,m4a,3gp,3g2,mj2 @ 000001ded6599c80] Referenced QT chapter track
 not found
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
 'D:\Users\Babs\Desktop\CA00666_Multitaction video price oil 2.mov':
   Metadata:
     major_brand     : qt
     minor_version   : 537199360
     compatible_brands: qt
     creation_time   : 2020-09-29T21:42:32.000000Z
   Duration: 00:00:39.90, start: 0.000000, bitrate: 547147 kb/s
     Stream #0:0(eng): Video: qtrle (rle  / 0x20656C72), bgra(progressive),
 4350x1920, 546937 kb/s, SAR 1:1 DAR 145:64, 30 fps, 30 tbr, 30 tbn, 30 tbc
 (default)
     Metadata:
       creation_time   : 2020-09-29T21:42:32.000000Z
       handler_name    : Apple Alias Data Handler
       encoder         : Animation
       timecode        : 00:00:00:01
     Stream #0:1(eng): Data: none (tmcd / 0x64636D74) (default)
     Metadata:
       creation_time   : 2020-09-29T21:42:32.000000Z
       handler_name    : Apple Alias Data Handler
       timecode        : 00:00:00:01
 Stream mapping:
   Stream #0:0 -> #0:0 (qtrle (native) -> flv1 (flv))
 Press [q] to stop, [?] for help
 Output #0, flv, to 'D:\Users\Babs\Desktop\FFMPEG\teste4.flv':
   Metadata:
     major_brand     : qt
     minor_version   : 537199360
     compatible_brands: qt
     encoder         : Lavf58.16.100
     Stream #0:0(eng): Video: flv1 (flv) ([2][0][0][0] / 0x0002), yuv420p,
 4350x1920 [SAR 1:1 DAR 145:64], q=2-31, 4000 kb/s, 30 fps, 1k tbn, 30 tbc
 (default)
     Metadata:
       creation_time   : 2020-09-29T21:42:32.000000Z
       handler_name    : Apple Alias Data Handler
       timecode        : 00:00:00:01
       encoder         : Lavc58.19.102 flv

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Ticket URL: <https://trac.ffmpeg.org/ticket/8905>
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