我发现了以下问题并尝试将 mp4 视频发送到我的相机： ffmpeg 有没有办法将视频发送到 Ubuntu 上的 /dev/video0？
我使用了以下命令：
ffmpeg -re -i fakezoom.mp4 -map 0:v -f h264 /dev/video0
根据Ubuntu，mp4的文件属性为H.264、每秒30帧、414kbps比特率。
当我运行该命令时，我得到以下输出：
ffmpeg -re -i fakezoom.mp4 -map 0:v -f h264 /dev/video0
ffmpeg version 4.2.4-1ubuntu0.1 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
configuration: --prefix=/usr --extra-version=1ubuntu0.1 --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-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --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-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
WARNING: library configuration mismatch
avcodec configuration: --prefix=/usr --extra-version=1ubuntu0.1 --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-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --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-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared --enable-version3 --disable-doc --disable-programs --enable-libaribb24 --enable-liblensfun --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libtesseract --enable-libvo_amrwbenc
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
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x56370afc9700] st: 0 edit list: 1 Missing key frame while searching for timestamp: 0
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x56370afc9700] st: 0 edit list 1 Cannot find an index entry before timestamp: 0.
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'fakezoom.mp4':
Metadata:
major_brand : isom
minor_version : 0
compatible_brands: mp41avc1
creation_time : 2021-04-20T09:39:14.000000Z
encoder : vlc 3.0.9.2 stream output
encoder-eng : vlc 3.0.9.2 stream output
Duration: 00:13:18.78, start: 0.000000, bitrate: 416 kb/s
Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, unknown/bt709/bt709), 1280x720 [SAR 1:1 DAR 16:9], 414 kb/s, 17.91 fps, 17.67 tbr, 90k tbn, 60 tbc (default)
Metadata:
creation_time : 2021-04-20T09:39:14.000000Z
handler_name : VideoHandler
File '/dev/video0' already exists. Overwrite ? [y/N] y
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0x56370afce880] using SAR=1/1B time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
[libx264 @ 0x56370afce880] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x56370afce880] profile High, level 3.1
Output #0, h264, to '/dev/video0':
Metadata:
major_brand : isom
minor_version : 0
compatible_brands: mp41avc1
encoder : Lavf58.29.100
Stream #0:0(eng): Video: h264 (libx264), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 17.67 fps, 17.67 tbn, 17.67 tbc (default)
Metadata:
creation_time : 2021-04-20T09:39:14.000000Z
handler_name : VideoHandler
encoder : Lavc58.54.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
av_interleaved_write_frame(): Invalid argumente=00:00:02.88 bitrate= 665.2kbits/s dup=0 drop=1 speed=0.408x
Error writing trailer of /dev/video0: Invalid argument
frame= 121 fps= 16 q=27.0 Lsize= 258kB time=00:00:03.22 bitrate= 654.2kbits/s dup=0 drop=1 speed=0.432x
video:258kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%
[libx264 @ 0x56370afce880] frame I:1 Avg QP:17.14 size: 45994
[libx264 @ 0x56370afce880] frame P:31 Avg QP:20.92 size: 9074
[libx264 @ 0x56370afce880] frame B:89 Avg QP:22.87 size: 853
[libx264 @ 0x56370afce880] consecutive B-frames: 0.8% 3.3% 0.0% 95.9%
[libx264 @ 0x56370afce880] mb I I16..4: 7.1% 77.3% 15.7%
[libx264 @ 0x56370afce880] mb P I16..4: 0.2% 2.1% 0.5% P16..4: 18.5% 7.1% 3.1% 0.0% 0.0% skip:68.4%
[libx264 @ 0x56370afce880] mb B I16..4: 0.0% 0.0% 0.0% B16..8: 10.1% 0.4% 0.1% direct: 0.3% skip:89.1% L0:48.1% L1:48.4% BI: 3.6%
[libx264 @ 0x56370afce880] 8x8 transform intra:76.2% inter:67.0%
[libx264 @ 0x56370afce880] coded y,uvDC,uvAC intra: 57.3% 80.2% 42.2% inter: 3.4% 5.5% 0.1%
[libx264 @ 0x56370afce880] i16 v,h,dc,p: 20% 15% 10% 55%
[libx264 @ 0x56370afce880] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 28% 13% 12% 7% 9% 11% 7% 7% 6%
[libx264 @ 0x56370afce880] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 18% 10% 6% 11% 11% 9% 6% 6%
[libx264 @ 0x56370afce880] i8c dc,h,v,p: 46% 20% 21% 13%
[libx264 @ 0x56370afce880] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x56370afce880] ref P L0: 56.5% 16.3% 20.0% 7.2%
[libx264 @ 0x56370afce880] ref B L0: 75.3% 20.1% 4.6%
[libx264 @ 0x56370afce880] ref B L1: 98.8% 1.2%
[libx264 @ 0x56370afce880] kb/s:470.92
Conversion failed!
它以对话失败结束，但也包含一些其他奇怪的消息，例如
av_interleaved_write_frame(): Invalid argumente=00:00:02.88 bitrate= 665.2kbits/s dup=0 drop=1 speed=0.408x
Error writing trailer of /dev/video0: Invalid argument
我做错什么了吗？
v4l2-ctl --list-devices
输出：
OBS Video Source (platform:v4l2loopback-000):
/dev/video10
UVC Camera (046d:081b) (usb-0000:02:00.0-5):
/dev/video0
/dev/video1
可能是因为我在那里使用了环回？当我想以正确的方式使用相机时，我有时会使用将 /dev/video0 映射到 video10 的程序来模拟绿屏并添加虚拟背景。
有人知道如何解决这个问题吗？
答案1
您链接的答案显示了如何制作“假摄像头”。这样，您选择的视频就可以定向到/dev/video*尚未被实际设备使用的摄像头。
应该不需要将视频输入到现有设备。这些设备只输出视频，所以我怀疑您是否可以将任意视频输入到相机。
运行时，sudo modprobe v4l2loopback它应该/dev/video使用当前未使用的 ID 号（例如/dev/video2）创建一个新的。然后运行：
ffmpeg -re -i fakezoom.mp4 -map 0:v -f v4l2 /dev/video2
-f h264请注意将问题中的 as改为-f v4l2。