我正在使用Fluent-FFmpeg与Node.JS一起制作文字覆盖在他们身上的视频，并且我希望随着视频的进展改变文字的颜色。
我的过滤器遵循以下模式：
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'
它打印出这些东西：
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
特别令人讨厌的一点：
[drawtext @ 0x7ff72d84bc00] Cannot find color '888888.000000'
然而，做这样的事情真的很不错：
fontcolor_expr=%{expr\\\\: if(between(t\\, 0\\, 20)\\, pink\\, white)}
打印出此错误：
[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
还没有很多fontcolor_expr的例子，所以我想知道是否有人有这方面的经验。有关在不创建多个过滤器的情况下动态更改fonrcolors的任何提示吗？
请注意fontcolor_expr=white和fontcolor_expr=888888有效并创建具有固定字体颜色的视频。
答案 0 :(得分：0)
我已经足够了解我需要的东西：
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'
具体做法是：
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if中运行eif语句并在结尾指定x，它将表达式的结果作为十六进制值返回。
为了在将来拯救某些人的麻烦，一切都必须妥善逃脱。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
将表达式的值和输出计算为格式化整数。 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＆＃34; printf＆＃34;完全相同。功能。第三个参数是可选的，它设置输出所占的位置数。它可用于从左侧添加带零的填充。