我可以使用 ffmpeg 进行屏幕录制：
ffmpeg -f x11grab -s 1280x800 -i :0.0 -c:v libx264 -framerate 30 -r 30 -crf 18 out.mkv
但是输出速度太快了。GTK RecordMyDesktop如果我启用动态编码，也会发生这种情况。所以，问题是如何获得正常的视频速度。此外，为了使用 ffmpeg 捕获声音，应该使用什么选项？
FFmpeg 输出：
ffmpeg -f x11grab -s 1280x800 -r 30 -i :0.0 -c:v libx264 -framerate 30 -r 30 -crf 18 out.mkv
ffmpeg version N-35162-g87244c8 Copyright (c) 2000-2012 the FFmpeg developers
built on Oct 7 2012 15:56:19 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
configuration: --enable-gpl --enable-libfaac --enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librtmp --enable-libtheora --enable-libvorbis --enable-libvpx --enable-x11grab --enable-libx264 --enable-nonfree --enable-version3
libavutil 51. 73.102 / 51. 73.102
libavcodec 54. 64.100 / 54. 64.100
libavformat 54. 29.105 / 54. 29.105
libavdevice 54. 3.100 / 54. 3.100
libavfilter 3. 19.102 / 3. 19.102
libswscale 2. 1.101 / 2. 1.101
libswresample 0. 16.100 / 0. 16.100
libpostproc 52. 1.100 / 52. 1.100
[x11grab @ 0xab896a0] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1280 height: 800
[x11grab @ 0xab896a0] shared memory extension found
[x11grab @ 0xab896a0] Estimating duration from bitrate, this may be inaccurate
Input #0, x11grab, from ':0.0':
Duration: N/A, start: 1350136942.608988, bitrate: 983040 kb/s
Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1280x800, 983040 kb/s, 30 tbr, 1000k tbn, 30 tbc
[libx264 @ 0xab87320] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64 SlowCTZ SlowAtom
[libx264 @ 0xab87320] profile High 4:4:4 Predictive, level 3.2, 4:4:4 8-bit
[libx264 @ 0xab87320] 264 - core 128 r2 198a7ea - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - 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=4 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=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=18.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, matroska, to 'out.mkv':
Metadata:
encoder : Lavf54.29.105
Stream #0:0: Video: h264, yuv444p, 1280x800, q=-1--1, 1k tbn, 30 tbc
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo -> libx264)
Press [q] to stop, [?] for help
frame= 10 fps=0.0 q=0.0 size= 1kB time=00:00:00.00 bitrate= 0.0kbits/sframe= 19 fps= 17 q=0.0 size= 1kB time=00:00:00.00 bitrate= 0.0kbits/sframe= 28 fps= 17 q=0.0 size= 1kB time=00:00:00.00 bitrate= 0.0kbits/sframe= 37 fps= 17 q=0.0 size= 1kB time=00:00:00.00 bitrate= 0.0kbits/sframe= 45 fps= 16 q=0.0 size= 1kB time=00:00:00.00 bitrate= 0.0kbits/sframe= 47 fps= 14 q=0.0 size= 1kB time=00:00:00.00 bitrate= 0.0kbits/sframe= 52 fps= 13 q=24.0 size= 257kB time=00:00:00.00 bitrate=2101632.0kbiframe= 55 fps= 12 q=24.0 size= 257kB time=00:00:00.10 bitrate=20808.2kbitsframe= 59 fps= 11 q=24.0 size= 289kB time=00:00:00.23 bitrate=10145.0kbitsframe= 64 fps= 11 q=24.0 size= 289kB time=00:00:00.40 bitrate=5894.7kbits/frame= 70 fps= 11 q=24.0 size= 289kB time=00:00:00.60 bitrate=3933.1kbits/frame= 72 fps= 10 q=24.0 size= 289kB time=00:00:00.66 bitrate=3549.2kbits/frame= 77 fps=9.8 q=24.0 size= 289kB time=00:00:00.83 bitrate=2837.7kbits/frame= 80 fps=9.6 q=24.0 size= 289kB time=00:00:00.93 bitrate=2533.5kbits/frame= 85 fps=9.3 q=24.0 size= 289kB time=00:00:01.10 bitrate=2146.9kbits/frame= 89 fps=9.3 q=24.0 size= 289kB time=00:00:01.23 bitrate=1917.1kbits/frame= 92 fps=9.1 q=24.0 size= 289kB time=00:00:01.33 bitrate=1773.3kbits/frame= 96 fps=9.0 q=24.0 size= 289kB time=00:00:01.46 bitrate=1612.4kbits/frame= 99 fps=8.8 q=24.0 size= 321kB time=00:00:01.56 bitrate=1676.8kbits/frame= 104 fps=8.7 q=24.0 size= 321kB time=00:00:01.73 bitrate=1515.2kbits/frame= 109 fps=5.3 q=24.0 Lsize= 1093kB time=00:00:03.56 bitrate=2511.5kbits/s
video:1092kB audio:0kB subtitle:0 global headers:0kB muxing overhead 0.120198%
[libx264 @ 0xab87320] frame I:3 Avg QP:18.93 size:142610
[libx264 @ 0xab87320] frame P:43 Avg QP:20.79 size: 15751
[libx264 @ 0xab87320] frame B:63 Avg QP:23.75 size: 195
[libx264 @ 0xab87320] consecutive B-frames: 21.1% 1.8% 11.0% 66.1%
[libx264 @ 0xab87320] mb I I16..4: 50.0% 21.1% 28.9%
[libx264 @ 0xab87320] mb P I16..4: 6.1% 0.9% 3.2% P16..4: 5.5% 1.2% 0.6% 0.0% 0.0% skip:82.5%
[libx264 @ 0xab87320] mb B I16..4: 0.4% 0.1% 0.0% B16..8: 2.9% 0.1% 0.0% direct: 0.0% skip:96.5% L0:40.7% L1:57.0% BI: 2.3%
[libx264 @ 0xab87320] 8x8 transform intra:14.5% inter:46.1%
[libx264 @ 0xab87320] coded y,u,v intra: 33.5% 24.1% 25.4% inter: 0.9% 0.4% 0.4%
[libx264 @ 0xab87320] i16 v,h,dc,p: 70% 26% 1% 3%
[libx264 @ 0xab87320] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 21% 30% 5% 7% 5% 7% 4% 10%
[libx264 @ 0xab87320] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 32% 35% 12% 2% 4% 3% 4% 3% 5%
[libx264 @ 0xab87320] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0xab87320] ref P L0: 57.0% 5.6% 26.8% 10.6%
[libx264 @ 0xab87320] ref B L0: 69.4% 22.6% 8.0%
[libx264 @ 0xab87320] ref B L1: 93.7% 6.3%
[libx264 @ 0xab87320] kb/s:2460.40
答案1
尝试使用无损编码器来捕获屏幕，然后在完成后重新编码输出以创建较小的文件（如果需要）。这种方法的优点通常是捕获过程不那么繁琐，从而可以实现“更快”的捕获帧速率。当然结果可能会有所不同。
ffmpeg -f x11grab -s 1280x800 -i :0.0 -c:v libx264 -preset ultrafast -crf 0 out.mkv
您的 CPU 可能根本无法以您声明的帧速率对特定屏幕捕获尺寸进行编码。在这种情况下，您可以尝试一个较小的-s值。也许值得尝试使用其他无损编码器，例如 huffyuv、ffv1 或 utvideo，但我个人还没有尝试过使用这些编码器进行截屏录制。
更多信息：
- 如何在 Linux 上正确进行屏幕录制
- 使用 FFmpeg 和 ALSA 捕获音频（作为脉冲的替代）