ffmpeg - FFmpeg fontcolor_expr to dynamically change fontcolor over time

Question

I'm using Fluent-FFmpeg with Node.JS to create videos with text overlaid on them and I'm wanting to change the color of the text as the video progresses.

My filters follow this pattern:

drawtext=enable='between(t,18.93,20.28)':fontfile=fonts/cousine-bold.ttf:fontsize=144:fontcolor_expr=%{expr\\\: if(between(t\\, 0\\, 20)\\, 888888\\, 111111)}:x=82:y=288:text='PROGRAMMING'

And it prints out this stuff:

ffmpeg version 3.3.2 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 8.1.0 (clang-802.0.42)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3.2 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libfreetype --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, mov,mp4,m4a,3gp,3g2,mj2, from 'uploads/0c719e39820366bc62c8fd66a6327828':
  Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    creation_time   : 2017-06-23T00:19:46.000000Z
    com.apple.quicktime.make: Apple
    com.apple.quicktime.model: MacBookPro9,2
    com.apple.quicktime.software: Mac OS X 10.12.5 (16F73)
    com.apple.quicktime.creationdate: 2017-06-22T17:18:42-0700
  Duration: 00:00:22.00, start: 0.000000, bitrate: 3408 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], 3091 kb/s, 15 fps, 15 tbr, 30k tbn, 50 tbc (default)
    Metadata:
      creation_time   : 2017-06-23T00:19:46.000000Z
      handler_name    : Core Media Data Handler
      encoder         : H.264
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 316 kb/s (default)
    Metadata:
      creation_time   : 2017-06-23T00:19:46.000000Z
      handler_name    : Core Media Data Handler
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x7ff72e810a00] using SAR=1/1
[libx264 @ 0x7ff72e810a00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x7ff72e810a00] profile High, level 3.1
[libx264 @ 0x7ff72e810a00] 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=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=-2 threads=6 lookahead_threads=1 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=15 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to './outputFile.mp4':
  Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    com.apple.quicktime.creationdate: 2017-06-22T17:18:42-0700
    com.apple.quicktime.make: Apple
    com.apple.quicktime.model: MacBookPro9,2
    com.apple.quicktime.software: Mac OS X 10.12.5 (16F73)
    encoder         : Lavf57.71.100
    Stream #0:0(und): Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 15 fps, 15360 tbn, 15 tbc (default)
    Metadata:
      creation_time   : 2017-06-23T00:19:46.000000Z
      handler_name    : Core Media Data Handler
      encoder         : Lavc57.89.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
    Stream #0:1(und): Audio: aac (LC) ([64][0][0][0] / 0x0040), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2017-06-23T00:19:46.000000Z
      handler_name    : Core Media Data Handler
      encoder         : Lavc57.89.100 aac
frame=   52 fps=0.0 q=27.0 size=      37kB time=00:00:04.66 bitrate=  65.7kbits/s speed=8.74x    
frame=   72 fps= 70 q=27.0 size=     187kB time=00:00:06.03 bitrate= 253.4kbits/s speed=5.83x    
frame=   95 fps= 61 q=27.0 size=     358kB time=00:00:07.52 bitrate= 390.4kbits/s speed=4.82x    
frame=  117 fps= 57 q=27.0 size=     569kB time=00:00:08.98 bitrate= 518.9kbits/s speed=4.35x    
frame=  137 fps= 53 q=27.0 size=     732kB time=00:00:10.32 bitrate= 580.2kbits/s speed=4.03x    
frame=  159 fps= 52 q=27.0 size=     942kB time=00:00:11.79 bitrate= 654.7kbits/s speed=3.84x    
frame=  180 fps= 50 q=27.0 size=    1110kB time=00:00:13.18 bitrate= 689.5kbits/s speed=3.67x    
frame=  204 fps= 50 q=27.0 size=    1331kB time=00:00:14.78 bitrate= 737.2kbits/s speed= 3.6x    
frame=  223 fps= 48 q=27.0 size=    1486kB time=00:00:16.06 bitrate= 757.9kbits/s speed=3.49x    
frame=  248 fps= 48 q=27.0 size=    1708kB time=00:00:17.71 bitrate= 789.7kbits/s speed=3.46x    
frame=  266 fps= 47 q=27.0 size=    1859kB time=00:00:18.92 bitrate= 805.0kbits/s speed=3.35x    
frame=  285 fps= 46 q=27.0 size=    2013kB time=00:00:20.19 bitrate= 816.4kbits/s speed=3.28x    
[drawtext @ 0x7ff72d84bc00] Cannot find color '888888.000000'
    Last message repeated 9 times
frame=  308 fps= 46 q=27.0 size=    2224kB time=00:00:21.75 bitrate= 837.5kbits/s speed=3.27x    
frame=  330 fps= 46 q=27.0 size=    2401kB time=00:00:21.96 bitrate= 895.5kbits/s speed=3.06x    
frame=  330 fps= 41 q=-1.0 Lsize=    2834kB time=00:00:22.00 bitrate=1055.0kbits/s speed=2.73x    
video:2484kB audio:338kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.441003%
[libx264 @ 0x7ff72e810a00] frame I:22    Avg QP:13.64  size: 47604
[libx264 @ 0x7ff72e810a00] frame P:154   Avg QP:16.76  size:  8574
[libx264 @ 0x7ff72e810a00] frame B:154   Avg QP:19.42  size:  1138
[libx264 @ 0x7ff72e810a00] consecutive B-frames:  6.7% 93.3%  0.0%  0.0%
[libx264 @ 0x7ff72e810a00] mb I  I16..4: 85.1% 13.3%  1.6%
[libx264 @ 0x7ff72e810a00] mb P  I16..4:  5.5%  3.1%  0.0%  P16..4: 41.5%  4.0%  5.5%  0.0%  0.0%    skip:40.4%
[libx264 @ 0x7ff72e810a00] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8: 14.7%  0.1%  0.0%  direct: 4.7%  skip:80.4%  L0:28.0% L1:71.4% BI: 0.7%
[libx264 @ 0x7ff72e810a00] 8x8 transform intra:21.7% inter:84.8%
[libx264 @ 0x7ff72e810a00] coded y,uvDC,uvAC intra: 60.5% 98.6% 92.9% inter: 6.0% 24.3% 3.1%
[libx264 @ 0x7ff72e810a00] i16 v,h,dc,p: 35% 19% 43%  3%
[libx264 @ 0x7ff72e810a00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 10%  7% 80%  1%  1%  1%  1%  0%  0%
[libx264 @ 0x7ff72e810a00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 33% 20% 45%  0%  0%  0%  0%  0%  0%
[libx264 @ 0x7ff72e810a00] i8c dc,h,v,p: 77%  9% 10%  4%
[libx264 @ 0x7ff72e810a00] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x7ff72e810a00] ref P L0: 75.3%  0.3% 17.1%  7.3%
[libx264 @ 0x7ff72e810a00] ref B L0: 80.0% 20.0%
[libx264 @ 0x7ff72e810a00] kb/s:924.66
[aac @ 0x7ff72e812200] Qavg: 2159.960

In particular this annoying bit:

[drawtext @ 0x7ff72d84bc00] Cannot find color '888888.000000'

However, it would be really nice to do something like this:

fontcolor_expr=%{expr\\\\: if(between(t\\, 0\\, 20)\\, pink\\, white)}

Which prints out this error:

[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
frame=  287 fps= 46 q=27.0 size=    2023kB time=00:00:20.31 bitrate= 815.9kbits/s speed=3.27x    
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Undefined constant or missing '(' in 'pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] [Eval @ 0x7fff5f7760c0] Missing ')' or too many args in 'if(between(t,0,20),pink,white)'
[Parsed_drawtext_0 @ 0x7ff3cf523300] Expression 'if(between(t, 0, 20), pink, white)' for the expr text expansion function is not valid

There aren't a lot of examples of fontcolor_expr, so I wanted to see if anyone had experience with this. Any tips on changing fonrcolors dynamically without creating multiple filters?

Please note that fontcolor_expr=white and fontcolor_expr=888888 are valid and create videos with a fixed font color.

score 0 · Accepted Answer

我已经想出足够的东西来满足我的需要：

drawtext=enable='between(t,18.93,20.28)':fontfile=fonts/cousine-bold.ttf:fontsize=144:fontcolor_expr=%{eif\\: if(between(t\, 18.93\, 19.02)\, 0xFFFFFF\, 0xFFB6C1) \\: x}:x=82:y=288:text='PROGRAMMING'

具体来说：

fontcolor_expr=%{eif\\: if(between(t\, 18.93\, 19.02)\, 0xFFFFFF\, 0xFFB6C1) \\: x}

据我所知eif :expression :format :decimal[optional]，允许以特定格式运行和返回表达式。通过在 in 中运行if语句eif并在末尾指定x，它将表达式的结果作为十六进制值返回。

只是为了以后给别人省点麻烦，一切都得好好躲避。在 Node.JS 中，我使用字符串插值，我的代码如下所示：

`drawtext=enable='between(t,${groupStart},${groupEnd})':fontfile=${fontFile}:fontsize=${fontSize}:fontcolor_expr=%{eif\\\\: if(between(t\\, ${groupStart}\\, ${wordStart})\\, 0xFFFFFF\\, 0xFFB6C1) \\\\: x}:x=${Math.floor((fontSize / 1.75) * xDistance)}:y=${Math.floor(fontSize * (lineCount + 1))}:text='${elem[0]}'`

expr_int_format, eif

评估表达式的值并输出为格式化整数。第一个参数是要计算的表达式，就像 expr 函数一样。第二个参数指定输出格式。允许的值为 x、X、d 和 u。它们的处理方式与“printf”函数中的完全相同。第三个参数是可选的，设置输出所占据的位置数。它可用于从左侧添加零填充。

来自：https ://www.mankier.com/1/ffmpeg-all

ffmpeg - FFmpeg fontcolor_expr to dynamically change fontcolor over time

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