我正在记录我的Electron应用程序的屏幕截图到文件中,就像在这里建议的那样:在Electron中保存捕获的视频到文件。
它运行得很好,但是文件是“传输流”。我可以在Chrome浏览器中播放它,但无法调整时间滑块。
建议使用
它运行得很好,但是文件是“传输流”。我可以在Chrome浏览器中播放它,但无法调整时间滑块。
建议使用
ffmpeg
对文件进行后处理。我找到的最简单、直接的命令是:ffmpeg -fflags +genpts -i in.webm out.webm
我认为这只是生成时间戳。然而,out.webm
文件比 in.webm
文件小了15倍!我没有看到任何质量上的变化。缺点是-处理时间与视频时长大致相同。
两个问题:
- 有没有办法加快这个“时间戳”过程的速度?
- 我能录制一个已经比原来小15倍的视频吗?
在调用webkitGetUserMedia()
时,我指定了maxFrameRate: 30
。
下面是那个ffmpeg
命令的输出:
vlad$ ffmpeg -fflags +genpts -i in.webm out.webm
ffmpeg version 4.3.2 Copyright (c) 2000-2021 the FFmpeg developers
built with Apple clang version 12.0.0 (clang-1200.0.32.29)
configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100
Input #0, matroska,webm, from 'in.webm':
Metadata:
encoder : Chrome
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv), 2560x1416, SAR 1:1 DAR 320:177, 1k tbr, 1k tbn, 1k tbc (default)
Metadata:
alpha_mode : 1
Stream mapping:
Stream #0:0 -> #0:0 (vp9 (native) -> vp9 (libvpx-vp9))
Press [q] to stop, [?] for help
[libvpx-vp9 @ 0x7f85f2012600] v1.9.0
[libvpx-vp9 @ 0x7f85f2012600] Neither bitrate nor constrained quality specified, using default CRF of 32
Output #0, webm, to 'out.webm':
Metadata:
encoder : Lavf58.45.100
Stream #0:0(eng): Video: vp9 (libvpx-vp9), yuv420p, 2560x1416 [SAR 1:1 DAR 320:177], q=-1--1, 1k fps, 1k tbn, 1k tbc (default)
Metadata:
alpha_mode : 1
encoder : Lavc58.91.100 libvpx-vp9
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame= 209 fps=5.8 q=0.0 Lsize= 881kB time=00:00:17.81 bitrate= 405.0kbits/s speed=0.494x
video:879kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.231567%
以下是 ffprobe
给出的有关这两个文件的信息:
vlad$ ffprobe in.webm
ffprobe version 4.3.2 Copyright (c) 2007-2021 the FFmpeg developers
built with Apple clang version 12.0.0 (clang-1200.0.32.29)
configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100
Input #0, matroska,webm, from 'in.webm':
Metadata:
encoder : Chrome
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv), 2560x1416, SAR 1:1 DAR 320:177, 1k tbr, 1k tbn, 1k tbc (default)
Metadata:
alpha_mode : 1
并且
vlad$ ffprobe out.webm
ffprobe version 4.3.2 Copyright (c) 2007-2021 the FFmpeg developers
built with Apple clang version 12.0.0 (clang-1200.0.32.29)
configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100
Input #0, matroska,webm, from 'out.webm':
Metadata:
ENCODER : Lavf58.45.100
Duration: 00:00:17.82, start: 0.000000, bitrate: 405 kb/s
Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv), 2560x1416, SAR 1:1 DAR 320:177, 1k tbr, 1k tbn, 1k tbc (default)
Metadata:
ALPHA_MODE : 1
ENCODER : Lavc58.91.100 libvpx-vp9
DURATION : 00:00:17.815000000