[FFmpeg-user] taking audio and video inputs from different devices

[Ricardo Kleemann]

Hi,

I’m not having much success mixing in audio from the default audio input with the video. The video comes out fine but audio is basically inaudible with intermittent a little bit of static.

I don’t know if I have the proper settings, I do know that if I don’t use the async flag then the video plays back in very fast forward.

the avfoundation “none:1” would be to use the default built-in audio 


$ ffmpeg -f avfoundation -i "none:1" -ac 2 -f decklink -re -i 'UltraStudio Mini Recorder at 9' -vcodec libx264 -crf 20 -preset veryfast -vf scale=640:360 -async 1 out7.mp4
ffmpeg version N-73104-g7604358 Copyright (c) 2000-2015 the FFmpeg developers
  built with Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)
  configuration: --prefix=/usr/local --enable-gpl --enable-nonfree --enable-ffplay --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-decklink --extra-cflags=-I/Users/ptl/blackmagicsdk/Mac/include --extra-ldflags=-L/Users/ptl/blackmagicsdk/Mac/include
  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 44.100 / 56. 44.100
  libavformat    56. 38.100 / 56. 38.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 17.100 /  5. 17.100
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, avfoundation, from 'none:1':
  Duration: N/A, start: 28853.224036, bitrate: 2822 kb/s
    Stream #0:0: Audio: pcm_f32le, 44100 Hz, stereo, flt, 2822 kb/s
[decklink @ 0x7f8362024800] Found Decklink mode 1920 x 1080 with rate 29.97
[decklink @ 0x7f8362024800] Frame received (#1) - No input signal detected - Frames dropped 1
Guessed Channel Layout for  Input Stream #1.0 : stereo
Input #1, decklink, from 'UltraStudio Mini Recorder at 9':
  Duration: N/A, start: 0.000000, bitrate: 1536 kb/s
    Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
    Stream #1:1: Video: rawvideo (UYVY / 0x59565955), uyvy422, 1920x1080, -5 kb/s, 29.97 tbr, 1000k tbn, 29.97 tbc
File 'out7.mp4' already exists. Overwrite ? [y/N] [decklink @ 0x7f8362024800] Frame received (#2) - Input returned - Frames dropped 2
y
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
-async is forwarded to lavfi similarly to -af aresample=async=1:min_hard_comp=0.100000:first_pts=0.
[libx264 @ 0x7f83618ad000] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x7f83618ad000] profile High 4:2:2, level 3.0, 4:2:2 8-bit
[libx264 @ 0x7f83618ad000] 264 - core 144 r2533 c8a773e - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=2 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=2 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=1 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=10 rc=crf mbtree=1 crf=20.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'out7.mp4':
  Metadata:
    encoder         : Lavf56.38.100
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv422p, 640x360, q=-1--1, 29.97 fps, 30k tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc56.44.100 libx264
    Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 44100 Hz, stereo, s16, 128 kb/s
    Metadata:
      encoder         : Lavc56.44.100 libfdk_aac
Stream mapping:
  Stream #1:1 -> #0:0 (rawvideo (native) -> h264 (libx264))
  Stream #0:0 -> #0:1 (pcm_f32le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
[decklink @ 0x7f8362024800] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
frame=   17 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A dup=10 dr[avfoundation @ 0x7f8362015800] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
frame=   32 fps= 32 q=26.0 size=      52kB time=00:00:00.34 bitrate=1230.7kbits/frame=   47 fps= 31 q=26.0 size=     194kB time=00:00:00.90 bitrate=1754.8kbits/frame=   62 fps= 31 q=26.0 size=     338kB time=00:00:01.36 bitrate=2023.0kbits/