[FFmpeg-trac] #6605(avfilter:new): Drawing subtitles on transparent video creates empty output
FFmpeg
trac at avcodec.org
Mon Aug 21 19:40:26 EEST 2017
#6605: Drawing subtitles on transparent video creates empty output
-----------------------------------+--------------------------------------
Reporter: slhck | Type: defect
Status: new | Priority: normal
Component: avfilter | Version: git-master
Keywords: subtitles | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-----------------------------------+--------------------------------------
Trying to render subtitles on a transparent video background produces an
empty, transparent PNG with no subtitles:
{{{
$ cat subs.srt
1
00:00:00,000 --> 00:00:02,000
<i>Test</i>
$ ffmpeg -f lavfi -i
"color=color=white at 0.0:size=100x100,format=rgba,subtitles=subs.srt"
-frames:v 1 out.png
ffmpeg version N-87010-g3c99523-tessus Copyright (c) 2000-2017 the FFmpeg
developers
built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --extra-
version=tessus --enable-avisynth --enable-fontconfig --enable-gpl
--enable-libass --enable-libbluray --enable-libfreetype --enable-libgsm
--enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libopus --enable-libsnappy --enable-
libsoxr --enable-libspeex --enable-libtheora --enable-libvidstab --enable-
libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack
--enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid
--enable-libzmq --enable-libzvbi --enable-version3 --disable-ffplay
--disable-indev=qtkit
libavutil 55. 74.100 / 55. 74.100
libavcodec 57.102.100 / 57.102.100
libavformat 57. 76.100 / 57. 76.100
libavdevice 57. 7.100 / 57. 7.100
libavfilter 6. 99.100 / 6. 99.100
libswscale 4. 7.102 / 4. 7.102
libswresample 2. 8.100 / 2. 8.100
libpostproc 54. 6.100 / 54. 6.100
[Parsed_subtitles_2 @ 0x7fd134d00740] Shaper: FriBidi 0.19.2 (SIMPLE)
[Parsed_subtitles_2 @ 0x7fd134d00740] Using font provider coretext
[Parsed_subtitles_2 @ 0x7fd134d00740] fontselect: (Arial, 400, 0) ->
/Library/Fonts/Arial.ttf, -1, ArialMT
[Parsed_subtitles_2 @ 0x7fd134d00740] fontselect: (Arial, 400, 100) ->
/Library/Fonts/Arial Italic.ttf, -1, Arial-ItalicMT
Input #0, lavfi, from
'color=color=white at 0.0:size=100x100,format=rgba,subtitles=subs.srt':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: rawvideo (RGBA / 0x41424752), rgba, 100x100 [SAR
1:1 DAR 1:1], 25 tbr, 25 tbn, 25 tbc
File 'out.png' already exists. Overwrite ? [y/N] y
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> png (native))
Press [q] to stop, [?] for help
Output #0, image2, to 'out.png':
Metadata:
encoder : Lavf57.76.100
Stream #0:0: Video: png, rgba, 100x100 [SAR 1:1 DAR 1:1], q=2-31, 200
kb/s, 25 fps, 25 tbn, 25 tbc
Metadata:
encoder : Lavc57.102.100 png
frame= 1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
speed=9.16x
video:1kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: unknown
}}}
When using `yuv420p` in the `color` filter, the output looks as expected
(just with opaque background).
This is somewhat related to #3302
--
Ticket URL: <https://trac.ffmpeg.org/ticket/6605>
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