Hello,
I'm trying to use ffmpeg to record the computer screen and also audio from
microfone. Googling I found a lot of "how to". Although I can now record, I do
have a few questions (3):
1) Using command
$ ffmpeg -thread_queue_size 512 -f alsa -ac 2 -ar 44100 -i hw:0,0 -video_size
1024x768 -probesize 10M -framerate 30 -thread_queue_size 512 -f x11grab -i :0.0
-c:a aac -c:v libx264 -vf "format=yuv420p" output.mp4
ffmpeg version N-98341-gcca982ee01 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --toolchain=hardened --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-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm
--enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264
--enable-shared
libavutil 56. 55.100 / 56. 55.100
libavcodec 58. 93.100 / 58. 93.100
libavformat 58. 47.100 / 58. 47.100
libavdevice 58. 11.100 / 58. 11.100
libavfilter 7. 86.100 / 7. 86.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 8.100 / 5. 8.100
libswresample 3. 8.100 / 3. 8.100
libpostproc 55. 8.100 / 55. 8.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, alsa, from 'hw:0,0':
Duration: N/A, start: 1593480535.223265, bitrate: 1411 kb/s
Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
Input #1, x11grab, from ':0.0':
Duration: N/A, start: 1593480535.257288, bitrate: 754974 kb/s
Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1024x768, 754974
kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
Stream mapping:
Stream #1:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Stream #0:0 -> #0:1 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x55a51bf2fb00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2
AVX
[libx264 @ 0x55a51bf2fb00] profile High, level 3.1
[libx264 @ 0x55a51bf2fb00] 264 - core 155 r2917 0a84d98 - H.264/MPEG-4 AVC
codec - Copyleft 2003-2018 - 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=-2 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=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4
ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'output.mp4':
Metadata:
encoder : Lavf58.47.100
Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661),
yuv420p(progressive), 1024x768, q=-1--1, 30 fps, 15360 tbn, 30 tbc
Metadata:
encoder : Lavc58.93.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp,
128 kb/s
Metadata:
encoder : Lavc58.93.100 aac
frame= 19 fps=0.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A speed=
frame= 34 fps= 34 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A speed=
frame= 49 fps= 32 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A speed=
frame= 64 fps= 32 q=29.0 size= 0kB time=00:00:00.39 bitrate=
1.0kbits/frame= 79 fps= 31 q=29.0 size= 0kB time=00:00:00.90 bitrate=
0.4kbits/frame= 95 fps= 31 q=29.0 size= 0kB time=00:00:01.40 bitrate=
0.3kbits/frame= 110 fps= 31 q=29.0 size= 0kB time=00:00:01.90 bitrate=
0.2kbits/frame= 125 fps= 31 q=29.0 size= 0kB time=00:00:02.40 bitrate=
0.2kbits/frame= 140 fps= 31 q=29.0 size= 0kB time=00:00:02.92 bitrate=
0.1kbits/frame= 156 fps= 31 q=29.0 size= 0kB time=00:00:03.43 bitrate=
0.1kbits/frame= 162 fps= 28 q=-1.0 Lsize= 208kB time=00:00:05.30 bitrate=
321.1kbits/s speed=0.93x
video:143kB audio:59kB subtitle:0kB other streams:0kB global headers:0kB muxing
overhead: 3.221925%
[libx264 @ 0x55a51bf2fb00] frame I:1 Avg
