我有 3 个连续的 FFmpeg 命令，可以自定义音频音量、自定义视频音量以及将amerge音频和视频自定义为最终输出。
第一个命令，编辑 mp3 文件的音量级别
ffmpeg -i music.mp3 -vol 100 music2.mp3
第二条命令，编辑 mp4 文件的音量级别
ffmpeg -i video.mp4 -vol 200 video2.mp4
第三条命令，合并music2.mp3并video2.mp4
ffmpeg -i music2.mp3 -i ruby.mp4 -filter_complex \
"[0:a][1:a]amerge,pan=stereo:c0<c0+c2:c1<c1+c3[out]" \
-map 1:v -map "[out]" -c:v copy -c:a libfdk_aac -shortest video2.mp4
有没有简单的方法可以将流程简化并分解为一个流程/命令？
我已经尝试过这个，但是没有用：
ffmpeg -i music.mp3 -vol 100 -i video.mp4 -vol 200 -filter_complex \
"[0:a][1:a]amerge,pan=stereo:c0<c0+c2:c1<c1+c3[out]" \
-map 1:v -map "[out]" -c:v copy -c:a libfdk_aac -shortest output.mp4
错误日志：
ffmpeg version N-60332-ga0d5204 Copyright (c) 2000-2014 the FFmpeg developers
built on Feb 4 2014 21:31:51 with Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
configuration: --prefix=/usr/local --enable-gpl --enable-nonfree --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid
libavutil 52. 63.100 / 52. 63.100
libavcodec 55. 49.101 / 55. 49.101
libavformat 55. 29.101 / 55. 29.101
libavdevice 55. 7.100 / 55. 7.100
libavfilter 4. 1.102 / 4. 1.102
libswscale 2. 5.101 / 2. 5.101
libswresample 0. 17.104 / 0. 17.104
libpostproc 52. 3.100 / 52. 3.100
Input #0, mp3, from 'adele.mp3':
Metadata:
title : Chasing Pavements
artist : Adele
track : 3
album : 19 (Deluxe Edition)
date : 2008
Duration: 00:03:30.55, start: 0.025056, bitrate: 160 kb/s
Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 159 kb/s
Stream #0:1: Video: mjpeg, yuvj420p(pc), 600x600 [SAR 72:72 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
Metadata:
title :
comment : Other
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'Ruby on Rails 101- What is Ruby on Rails_.mp4':
Metadata:
major_brand : mp42
minor_version : 0
compatible_brands: isommp42
creation_time : 2013-12-21 07:56:20
Duration: 00:05:42.40, start: 0.000000, bitrate: 1214 kb/s
Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 1020 kb/s, 30 fps, 30 tbr, 60 tbn, 60 tbc (default)
Metadata:
handler_name : VideoHandler
Stream #1:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 191 kb/s (default)
Metadata:
creation_time : 2013-12-21 07:56:23
handler_name : IsoMedia File Produced by Google, 5-11-2011
[Parsed_pan_1 @ 0x7fcd23d00680] This syntax is deprecated. Use '|' to separate the list items.
-vol has been deprecated. Use the volume audio filter instead.
-vol is forwarded to lavfi similarly to -af volume=0.781250.
-vol has been deprecated. Use the volume audio filter instead.
-vol is forwarded to lavfi similarly to -af volume=0.781250.
File 'output.mp4' already exists. Overwrite ? [y/N] y
[Parsed_amerge_0 @ 0x7fcd23d00000] No channel layout for input 1
Last message repeated 1 times
[AVFilterGraph @ 0x7fcd23c0f5a0] The following filters could not choose their formats: Parsed_amerge_0
Consider inserting the (a)format filter near their input or output.
答案1
一个命令即可绑定
您可以使用一个命令执行此操作volume音频过滤器而不是旧-vol选项（如控制台输出所述）：
ffmpeg -i music.mp3 -i videowithaudio.mp4 -filter_complex \
"[0:a]volume=0.390625[a1];[1:a]volume=0.781250[a2]; \
[a1][a2]amerge,pan=stereo:c0<c0+c2:c1<c1+c3[out]" \
-map 1:v -map "[out]" -c:v copy -c:a libfdk_aac -shortest output.mp4
您可能需要调整的值volume。
潜在问题
语法已弃用
[Parsed_pan_4 @ 0x244c980] This syntax is deprecated. Use '|' to separate the list items.
别担心——你可以忽略此消息。
无法选择格式
[AVFilterGraph @ 0x26549a0] The following filters could not choose their formats: Parsed_amerge_3
Consider inserting the (a)format filter near their input or output.
所有输入必须具有相同的采样率和格式amerge。如果它们不同，那么你将必须使用aformat音频过滤器：
ffmpeg -i music.mp3 -i videowithaudio.mp4 -filter_complex \
"[0:a]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo,volume=0.5[a1]; \
[1:a]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo,volume=0.8[a2]; \
[a1][a2]amerge,pan=stereo:c0<c0+c2:c1<c1+c3[out]" \
-map 1:v -map "[out]" -c:v copy -c:a libfdk_aac -shortest output.mp4