Java 调用 FFMPEG 的坑人之处

昨天用 ubuntu 20.04 安装的 ffmpeg 进行视频转码时，出现了一个奇葩的问题，用命令行能过的指令，通过 Java 调用死活不行。原来Java 调用的默认允许协议与命令行的竟然不一样（至于为什么不一样，还没有找到答案...）。

Java 调用 FFMPEG 命令时用 url 作为输入源，Linux 下出现 “no such file or directory” 问题的解决

ffmpeg version 4.2.2-1ubuntu1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-3ubuntu1)
  configuration: --prefix=/usr --extra-version=1ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64
 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass -
-enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libf
ribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-l
ibpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable
-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable
-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec
61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
"https://video.example.com/video/ece851398dba2dc26df0e9ccba7fbe00/MULTI-ece851398dba2dc26df0e9ccba7fbe00-130961929/videos_200.mp4": No such file or directory

这个No such file or directory 根本不是文件不存在，下载到本地也会报同样的错

通过'ffmpeg -loglevel debug' 首先增加调试参数。
你会看到错误输出：

ffmpeg version 4.2.2-1ubuntu1 Copyright (c) 2000-2019 the ...
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument 'debug'.
0-130961929/videos_200.mp4"'.
Reading option '-vcodec' ... matched as option 'vcodec' (force video codec ('copy' to copy stream)) with argument 'libwebp'.
Reading option '-lossless' ... matched as AVOption 'lossless' with argument '0'.
Reading option '-qscale' ... matched as option 'qscale' (use fixed quality scale (VBR)) with argument '75'.
Reading option '-preset' ... matched as AVOption 'preset' with argument 'default'.
Reading option '-loop' ... matched as AVOption 'loop' with argument '0'.
Reading option '-an' ... matched as option 'an' (disable audio) with argument '1'.
Reading option '-vsync' ... matched as option 'vsync' (video sync method) with argument '0'.
Reading option '/tmp/output.webp' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option loglevel (set logging level) with argument debug.
Applying option vsync (video sync method) with argument 0.
Successfully parsed a group of options.
Parsing a group of options: input url "https://video.example.com/video/ece851398dba2dc26df0e9ccba7fbe00/MULTI-ece851398dba2dc26df0e9ccba7fbe00-130961929/videos_200
.mp4".
Applying option c (codec name) with argument /bin/sh.
Successfully parsed a group of options.
Opening an input file: "https://video.example.com/video/ece851398dba2dc26df0e9ccba7fbe00/MULTI-ece851398dba2dc26df0e9ccba7fbe00-130961929/videos_200.mp4".
[NULL @ 0x55fd7533f440] Opening '"https://video.example.com/video/ece851398dba2dc26df0e9ccba7fbe00/MULTI-ece851398dba2dc26df0e9ccba7fbe00-130961929/videos_200.mp4"
' for reading
[file @ 0x55fd7533fec0] Setting default whitelist 'file,crypto'
"https://video.example.com/video/ece851398dba2dc26df0e9ccba7fbe00/MULTI-ece851398dba2dc26df0e9ccba7fbe00-130961929/videos_200.mp4": No such file or directory

这里最重要的信息是

Setting default whitelist 'file,crypto'

在搜索过程以下两个链接非常有帮助：

https://blog.yo1.dog/fix-for-...

https://stackoverflow.com/a/1...

可以通过参数 '-report' 将完整的命令行和控制台输出转储到当前目录中名为 program-YYYYMMDD-HHMMSS.log 的文件中。该文件对于调试错误很有用。它默认为-loglevel verbose级别的日志输出。也可以通过设置FFREPORT环境变量来实现同样的效果:

FFREPORT="level=32:file=abc.log" ffmpeg -v verbose ...

以下是上面第一个链接的翻译：

修复FFmpeg“协议不在白名单上” HTTP（S）URL错误

使用-safe 0和-protocol_whitelist file,http,https,tcp,tls 参数。完整示例在最底部。

---

我试图像这样使用FFmpeg的concat多路分配器：

# inputs.txt
file 'http://www.example1.com/video1.mp4'  
file 'https://www.example2.com/video2.mp4'  

ffmpeg -f "concat" -i "./inputs.txt" -codec "copy" "./concated.mp4"  

首先我得到了错误：

[concat @ 0x00] Unsafe file name 'http://www.example1.com/video1.mp4'
./inputs.txt: Operation not permitted

这通过添加-safe 0参数来解决。然后我得到了错误：

[http @ 0x00] Protocol not on whitelist 'file,crypto'!
[concat @ 0x00] Impossible to open 'http://www.example1.com/video1.mp4'
./inputs.txt: Invalid argument

我以为我可以通过简单的添加来解决这个问题，-protocol_whitelist file,http,https但是错误变成了：

[tcp @ 0x00] Protocol not on whitelist 'file,http,https'!
[concat @ 0x00] Impossible to open 'http://www.example1.com/video1.mp4'
./inputs.txt: Invalid argument

我不明白为什么我的HTTP协议输入仍然被拒绝。http显然在协议白名单中。然后，我注意到前两个错误之间的差别很小。看那些错误中的第一个单词。httpVS tcp。我意识到错误之前括号中的第一个单词是被拒绝的协议。

解决方案是也要添加tcp到协议白名单中（tls如果要支持HTTPS ，也要添加到协议白名单中）。这是我的最终命令：

ffmpeg -f "concat" -safe "0" -protocol_whitelist "file,http,https,tcp,tls" -i "./inputs.txt" -codec "copy" "./concated.mp4"