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• FFMPEG Incredibly Slow On Windows Server 2016

  1er août 2019, par Ben Gardner

  I have a t2.small (2GB RAM, 1 vCPU) Amazon EC2 instance running a process using FFMPEG. It runs just fine ( 30 fps) on my computer (i7, 12GB RAM), but at around 2 fps on the server. Here’s the command :

  rescale_command = f'ffmpeg -i {srcVideo} -filter_complex \"scale={owidth}:{oheight}, setsar=1:1, pad={dim[0]}:{dim[1]}:{oofx}:{oofy}\" {destVideo}'

  I’ve tried uninstalling and reinstalling ffmpeg/ffprobe

  Edited per llogan’s request, I’ve also discovered that it’s relatively speedy towards the beginning (I’m rescaling 100 times over the course of the program) and slows down towards the end.

  It utilizes 100% of the CPU even from the beginning, though.

  Example command/output :
  ffmpeg -i media/8-1-2019/hi/dl-107.mp4 -filter_complex "scale=607:1080, setsar=1:1, pad=1920:1080:656:0" media/8-1-2019/hi/sl-107.mp4

  ffmpeg version 3.2 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.4.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 34.100 / 55. 34.100
  
    libavcodec     57. 64.100 / 57. 64.100
  
    libavformat    57. 56.100 / 57. 56.100
  
    libavdevice    57.  1.100 / 57.  1.100
  
    libavfilter     6. 65.100 /  6. 65.100
  
    libswscale      4.  2.100 /  4.  2.100
  
    libswresample   2.  3.100 /  2.  3.100
  
    libpostproc    54.  1.100 / 54.  1.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'media/8-1-2019/hi/dl-107.mp4':
  
    Metadata:
  
      minor_version   : 512
  
      major_brand     : isom
  
      compatible_brands: isomiso2avc1mp41
  
      comment         : vid:v09044ce0000bks3802jqrog167l3rf0
  
      encoder         : Lavf58.20.100
  
    Duration: 00:00:15.12, start: 0.000000, bitrate: 1046 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 540x960 [SAR 1:1 DAR 9:16], 972 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 64 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
  [Parsed_setsar_1 @ 00000000023ac840] num:den syntax is deprecated, please use num/den or named options instead
  
  [Parsed_setsar_1 @ 00000000023ad2c0] num:den syntax is deprecated, please use num/den or named options instead
  
  [libx264 @ 00000000023ad800] using SAR=1/1
  
  [libx264 @ 00000000023ad800] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  [libx264 @ 00000000023ad800] profile High, level 4.0
  
  [libx264 @ 00000000023ad800] 264 - core 148 r2721 72d53ab - H.264/MPEG-4 AVC codec - Copyleft 2003-2016 - 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=1 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 'media/8-1-2019/hi/sl-107.mp4':
  
    Metadata:
  
      minor_version   : 512
  
      major_brand     : isom
  
      compatible_brands: isomiso2avc1mp41
  
      comment         : vid:v09044ce0000bks3802jqrog167l3rf0
  
      encoder         : Lavf57.56.100
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 29.97 fps, 30k tbn, 29.97 tbc (default)
  
      Metadata:
  
        encoder         : Lavc57.64.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
      Stream #0:1(und): Audio: aac (LC) ([64][0][0][0] / 0x0040), 44100 Hz, stereo, fltp, 128 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
        encoder         : Lavc57.64.100 aac
  
  Stream mapping:
  
    Stream #0:0 (h264) -> scale (graph 0)
  
    pad (graph 0) -> Stream #0:0 (libx264)
  
    Stream #0:1 -> #0:1 (aac (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  frame=  453 fps=3.6 q=29.0 Lsize=    3016kB time=00:00:15.01 bitrate=1645.7kbits/s speed=0.12x
  
  video:2763kB audio:237kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.576820%
  
  [libx264 @ 00000000023ad800] frame I:6     Avg QP:20.93  size: 38467
  
  [libx264 @ 00000000023ad800] frame P:118   Avg QP:23.12  size: 11624
  
  [libx264 @ 00000000023ad800] frame B:329   Avg QP:25.19  size:  3725
  
  [libx264 @ 00000000023ad800] consecutive B-frames:  1.8%  2.6%  4.6% 90.9%
  
  [libx264 @ 00000000023ad800] mb I  I16..4: 16.4% 76.7%  6.9%
  
  [libx264 @ 00000000023ad800] mb P  I16..4:  2.3%  5.8%  0.9%  P16..4:  9.8%  3.8%  1.6%  0.0%  0.0%    skip:75.7%
  
  [libx264 @ 00000000023ad800] mb B  I16..4:  0.4%  0.7%  0.1%  B16..8:  9.5%  1.6%  0.3%  direct: 0.6%  skip:86.8%  L0:43.0% L1:50.8% BI: 6.2%
  
  [libx264 @ 00000000023ad800] 8x8 transform intra:67.4% inter:78.3%
  
  [libx264 @ 00000000023ad800] coded y,uvDC,uvAC intra: 32.5% 40.1% 9.4% inter: 2.7% 3.9% 0.1%
  
  [libx264 @ 00000000023ad800] i16 v,h,dc,p: 50% 25%  6% 19%
  
  [libx264 @ 00000000023ad800] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 38% 11% 27%  3%  3%  5%  3%  6%  3%
  
  [libx264 @ 00000000023ad800] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 43% 11% 12%  5%  7%  9%  4%  7%  3%
  
  [libx264 @ 00000000023ad800] i8c dc,h,v,p: 62% 11% 22%  5%
  
  [libx264 @ 00000000023ad800] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 00000000023ad800] ref P L0: 64.4% 14.3% 16.1%  5.2%
  
  [libx264 @ 00000000023ad800] ref B L0: 90.6%  7.5%  2.0%
  
  [libx264 @ 00000000023ad800] ref B L1: 97.7%  2.3%
  
  [libx264 @ 00000000023ad800] kb/s:1496.84
  
  [aac @ 0000000000628120] Qavg: 754.761

• ffmpeg doesn't correctly work with mkv

  26 avril 2017, par Alex

  Now I’m trying to trim mkv file with ffmpeg command.

  ffmpeg -y -i 1.mkv -filter_complex "[0:0]trim=start=201:duration=28,setpts=PTS-STARTPTS" a.mp4

  after processing a.mp4 is created with length(28s), but there is problems.

  1. Video is some flapped while playing.
  2. Audio is continued though playing has ended beyond 28s.

  So could you guys tell me what can I do ?

  When ffmpeg processing, it shows some errors as like this :

  D:\Work\ffmpeg\files> ffmpeg -y -i 1.mkv -filter_complex "[0:0]trim=start=201:duration=28,setpts=PTS-STARTPTS" a.mp4
  
  ffmpeg version N-77883-gd7c75a5 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.2.0 (GCC)
  
    configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 13.100 / 55. 13.100
  
    libavcodec     57. 22.100 / 57. 22.100
  
    libavformat    57. 21.101 / 57. 21.101
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 25.100 /  6. 25.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Guessed Channel Layout for  Input Stream #0.1 : mono
  
  Input #0, matroska,webm, from '1.mkv':
  
    Metadata:
  
      ENCODER         : Lavf56.1.0
  
    Duration: 00:35:40.08, start: 0.000000, bitrate: 348 kb/s
  
      Stream #0:0: Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 29.97 fps, 29.97 tbr, 1k tbn, 1k tbc
  
      Stream #0:1: Audio: pcm_mulaw ([7][0][0][0] / 0x0007), 8000 Hz, 1 channels, s16, 64 kb/s
  
  [libx264 @ 000002859baf3300] using SAR=1/1
  
  [libx264 @ 000002859baf3300] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 000002859baf3300] profile High, level 3.0
  
  [libx264 @ 000002859baf3300] 264 - core 148 r2638 7599210 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - 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 'a.mp4':
  
    Metadata:
  
      encoder         : Lavf57.21.101
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=-1--1, 29.97 fps, 30k tbn, 29.97 tbc
  
      Metadata:
  
        encoder         : Lavc57.22.100 libx264
  
      Side data:
  
        unknown side data type 10 (24 bytes)
  
      Stream #0:1: Audio: aac (LC) ([64][0][0][0] / 0x0040), 8000 Hz, mono, fltp, 48 kb/s
  
      Metadata:
  
        encoder         : Lavc57.22.100 aac
  
  Stream mapping:
  
    Stream #0:0 (vp8) -> trim (graph 0)
  
    setpts (graph 0) -> Stream #0:0 (libx264)
  
    Stream #0:1 -> #0:1 (pcm_mulaw (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  [vp8 @ 000002859d9ae460] Discarding interframe without a prior keyframe!
  
  [vp8 @ 000002859d9aeb00] Discarding interframe without a prior keyframe!
  
  [vp8 @ 000002859e8eee40] Discarding interframe without a prior keyframe!
  
  [vp8 @ 000002859e8f5460] Discarding interframe without a prior keyframe!
  
  Error while decoding stream #0:0: Invalid data found when processing input
  
      Last message repeated 3 times
  
  frame=    0 fps=0.0 q=0.0 size=      62kB time=00:00:22.27 bitrate=  22.6kbits/s
  
  frame=    0 fps=0.0 q=0.0 size=     154kB time=00:00:41.08 bitrate=  30.6kbits/s
  
  frame=    0 fps=0.0 q=0.0 size=     255kB time=00:01:02.20 bitrate=  33.6kbits/s
  
  frame=    0 fps=0.0 q=0.0 size=     340kB time=00:01:19.34 bitrate=  35.1kbits/s
  
  frame=    0 fps=0.0 q=0.0 size=     423kB time=00:01:39.31 bitrate=  34.9kbits/s
  
  frame=   88 fps= 29 q=29.0 size=     518kB time=00:01:43.79 bitrate=  40.9kbits/
  
  frame=  140 fps= 40 q=29.0 size=     613kB time=00:01:45.46 bitrate=  47.6kbits/
  
  frame=  194 fps= 48 q=29.0 size=     719kB time=00:01:47.38 bitrate=  54.8kbits/
  
  
  
  ...
  
  
  
  
  
  frame=  839 fps= 14 q=29.0 size=   10881kB time=00:34:51.52 bitrate=  42.6kbits/
  
  frame=  839 fps= 14 q=29.0 size=   10962kB time=00:35:10.46 bitrate=  42.5kbits/
  
  frame=  839 fps= 14 q=29.0 size=   11031kB time=00:35:25.44 bitrate=  42.5kbits/
  
  frame=  839 fps= 14 q=-1.0 Lsize=   11266kB time=00:35:40.16 bitrate=  43.1kbits/s dup=284 drop=328 speed=34.6x
  
  video:1083kB audio:10104kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.706855%
  
  [libx264 @ 000002859baf3300] frame I:4     Avg QP:15.24  size: 22651
  
  [libx264 @ 000002859baf3300] frame P:305   Avg QP:19.95  size:  2626
  
  [libx264 @ 000002859baf3300] frame B:530   Avg QP:25.41  size:   408
  
  [libx264 @ 000002859baf3300] consecutive B-frames: 15.7%  0.0%  0.4% 83.9%
  
  [libx264 @ 000002859baf3300] mb I  I16..4: 15.9% 63.7% 20.4%
  
  [libx264 @ 000002859baf3300] mb P  I16..4:  0.3%  1.9%  0.3%  P16..4: 22.3%  6.2%  2.4%  0.0%  0.0%    skip:66.5%
  
  [libx264 @ 000002859baf3300] mb B  I16..4:  0.0%  0.1%  0.0%  B16..8: 16.1%  0.6%  0.1%  direct: 0.2%  skip:82.9%  L0:48.2% L1:48.5% BI: 3.4%
  
  [libx264 @ 000002859baf3300] 8x8 transform intra:71.1% inter:71.4%
  
  [libx264 @ 000002859baf3300] coded y,uvDC,uvAC intra: 72.2% 78.3% 40.7% inter: 5.9% 4.0% 0.1%
  
  [libx264 @ 000002859baf3300] i16 v,h,dc,p: 29% 30% 21% 20%
  
  [libx264 @ 000002859baf3300] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 28% 18% 14%  5%  6%  9%  6%  9%  6%
  
  [libx264 @ 000002859baf3300] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 38% 20% 11%  5%  5%  7%  5%  6%  4%
  
  [libx264 @ 000002859baf3300] i8c dc,h,v,p: 46% 16% 27% 11%
  
  [libx264 @ 000002859baf3300] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 000002859baf3300] ref P L0: 63.4% 21.5% 11.5%  3.6%
  
  [libx264 @ 000002859baf3300] ref B L0: 92.6%  6.4%  1.0%
  
  [libx264 @ 000002859baf3300] ref B L1: 96.4%  3.6%
  
  [libx264 @ 000002859baf3300] kb/s:316.59
  
  [aac @ 000002859baf4400] Qavg: 65377.508
  
  
  
  D:\Work\ffmpeg\files>

  ---

• compile ffmpeg with alsa support on Ubuntu 12.04 amd64

  6 octobre 2015, par user1129812

  I had followed the ffmpeg compile instructions described in "CompilationGuide/Ubuntu – FFmpeg" and had successfully compiled a version of ffmpeg on my Ubuntu 12.04 amd64 system. This compiled version of ffmpeg works ok for my normal usage. However, recently, I want to grab my Ubuntu desktop with sound from applications, I follow the instructions in "HOWTO : Proper Screencasting on Linux" and I use the command :

  ~/bin/ffmpeg -f alsa -ac 2 -i hw:0 -f x11grab -r 30 -s 1024x768 -i :0.0 -acodec pcm_s16le -vcodec libx264 -preset ultrafast -crf 0 -threads 0 out_video_test.mkv

  to want to grab my Ubuntu desktop with sound from application. The terminal output from this command is :

  ffmpeg version 2.4.git Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Oct 13 2014 17:38:17 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  
    configuration: --prefix=/home/tkwinfo/ffmpeg_build --extra-cflags=-I/home/tkwinfo/ffmpeg_build/include --extra-ldflags=-L/home/tkwinfo/ffmpeg_build/lib --bindir=/home/tkwinfo/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
  
    libavutil      54. 10.100 / 54. 10.100
  
    libavcodec     56.  4.101 / 56.  4.101
  
    libavformat    56.  9.100 / 56.  9.100
  
    libavdevice    56.  1.100 / 56.  1.100
  
    libavfilter     5.  1.103 /  5.  1.103
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  1.100 / 53.  1.100
  
  Guessed Channel Layout for  Input Stream #0.0 : stereo
  
  Input #0, alsa, from 'hw:0':
  
    Duration: N/A, start: 1444111224.703996, bitrate: 1536 kb/s
  
      Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
  
  [x11grab @ 0x3971360] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1024 height: 768
  
  [x11grab @ 0x3971360] shared memory extension found
  
  Input #1, x11grab, from ':0.0':
  
    Duration: N/A, start: 1444111224.739397, bitrate: 754974 kb/s
  
      Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1024x768, 754974 kb/s, 30 tbr, 1000k tbn, 30 tbc
  
  No pixel format specified, yuv444p for H.264 encoding chosen.
  
  Use -pix_fmt yuv420p for compatibility with outdated media players.
  
  [libx264 @ 0x39941e0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x39941e0] profile High 4:4:4 Predictive, level 3.1, 4:4:4 8-bit
  
  [libx264 @ 0x39941e0] 64 - core 142 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=0 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=cqp mbtree=0 qp=0
  
  Output #0, matroska, to 'out_video_test.mkv':
  
    Metadata:
  
      encoder         : Lavf56.9.100
  
      Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv444p, 1024x768, q=-1--1, 30 fps, 1k tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc56.4.101 libx264
  
      Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
  
      Metadata:
  
        encoder         : Lavc56.4.101 pcm_s16le
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
    Stream #0:0 -> #0:1 (pcm_s16le (native) -> pcm_s16le (native))
  
  Press [q] to stop, [?] for help
  
  frame=   16 fps=0.0 q=0.0 size=    1370kB time=00:00:00.54 bitrate=20438.5kbits/
  
  frame=   31 fps= 31 q=0.0 size=   etc, etc

  The video part is grabbed ok but there is no sound in the output video. I had followed the procedures described in the FAQ in "HOWTO : Proper Screencasting on Linux" to use "pavucontrol" to set "capture application audio instead of mic". However, I still could only grab video from my Ubuntu desktop.

  I find that I have installed libasound2-dev in my Ubuntu 12.04 amd64 system. The "libasound.so" file is in /usr/lib/x86_64-linux-gnu while the "asoundlib.h" file is in /usr/include/alsa. The config options when I compile ffmpeg is :

  PATH="$PATH:$HOME/bin" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure 
  
    --prefix="$HOME/ffmpeg_build" 
  
    --extra-cflags="-I$HOME/ffmpeg_build/include" 
  
    --extra-ldflags="-L$HOME/ffmpeg_build/lib" 
  
    --bindir="$HOME/bin" 
  
    --enable-gpl 
  
    --enable-libass 
  
    --enable-libfdk-aac 
  
    --enable-libfreetype 
  
    --enable-libmp3lame 
  
    --enable-libopus 
  
    --enable-libtheora 
  
    --enable-libvorbis 
  
    --enable-libvpx 
  
    --enable-libx264 
  
    --enable-nonfree 
  
    --enable-x11grab

  I want to know that how do I find out whether I have compiled the alsa support into my ffmpeg ? Do I need to add the ffmpeg config option

  --extra-libs=-lasound

  to get alsa support when compiling ffmpeg ? (as described in some discussions in the internet) If yes, how do I specify the paths of "libasound.so" and "asoundlib.h" so that they would be used in the ffmpeg compilation process ?

  Moreover, if alsa support is already compiled in my ffmpeg, what else should I try so as to be able to grab sound from application using my ffmpeg ?

  Any idea. Thanks for any suggestion.