ffmpeg "Error while opening encoder for output stream #0:1"

Question

Ok, this is probably a very stupid mistake on my part, but I am losing my head here. I have been using a simple command for transcoding MOV file for months now:

ffmpeg -i SOURCE.mov -c:v libx264 -profile:v baseline -pix_fmt yuv420 TRANSCODED.mp4

I never had a problem with that... until today. I am getting the aforementioned encoder error with this MOV (PCM24 LE, MPEG-2). Here is the log:

ffmpeg version 2.8.4 Copyright (c) 2000-2015 the FFmpeg developers   built with gcc 5.2.0 (GCC)   configuration: --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-lzma --enable-decklink --enable-zlib   libavutil      54. 31.100 / 54. 31.100   libavcodec     56. 60.100 /
56. 60.100   libavformat    56. 40.101 / 56. 40.101   libavdevice    56.  4.100 / 56.  4.100   libavfilter     5. 40.101 /  5. 40.101   libswscale      3.  1.101 /  3.  1.101   libswresample   1.  2.101 / 
1.  2.101   libpostproc    53.  3.100 / 53.  3.100 Guessed Channel Layout for  Input Stream #0.0 : 7.1 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'BL2.mov':   Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    creation_time   : 2017-03-14 21:48:34
    encoder         : FFmbc 0.7
    timecode        : 00:13:29;19   Duration: 00:12:53.57, start: 0.000000, bitrate: 59235 kb/s
    Stream #0:0(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 8 channels, s32 (24 bit), 9216 kb/s (default)
    Metadata:
      creation_time   : 2017-03-14 21:48:34
      handler_name    : Apple Alias Data Handler
    Stream #0:1(eng): Data: none (tmcd / 0x64636D74) (default)
    Metadata:
      creation_time   : 2017-03-14 21:48:34
      handler_name    : Apple Alias Data Handler
      timecode        : 00:13:29;19
    Stream #0:2(eng): Video: mpeg2video (4:2:2) (xd5b / 0x62356478), yuv422p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 50002 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
    Metadata:
      creation_time   : 2017-03-14 22:56:29
      handler_name    : Apple Alias Data Handler
      timecode        : 00:13:29;19 [libx264 @ 0354dc20] using SAR=1/1 [libx264 @ 0354dc20] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64 [libx264 @ 0354dc20] profile Constrained Baseline, level 4.0 [libx264 @ 0354dc20] 264 - core 148 r2638 7599210 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: cabac=0 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 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=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 [libvo_aacenc @ 03bb0200] Unable to set encoding parameters
Output #0, mp4, to 'bl2.mp4':   Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    timecode        : 00:13:29;19
    encoder         : FFmbc 0.7
    Stream #0:0(eng): Video: h264 (libx264), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 29.97 fps, 29.97 tbn, 29.97 tbc (default)
    Metadata:
      creation_time   : 2017-03-14 22:56:29
      handler_name    : Apple Alias Data Handler
      timecode        : 00:13:29;19
      encoder         : Lavc56.60.100 libx264
    Stream #0:1(eng): Audio: aac, 0 channels, 128 kb/s (default)
    Metadata:
      creation_time   : 2017-03-14 21:48:34
      handler_name    : Apple Alias Data Handler
      encoder         : Lavc56.60.100 libvo_aacenc
Stream mapping:   Stream #0:2 -> #0:0 (mpeg2video (native) -> h264 (libx264))   Stream
#0:0 -> #0:1 (pcm_s24le (native) -> aac (libvo_aacenc)) Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height

This seems to tell me that it is an audio issue (even though I transcoded an identically encoded file just last friday...):

[libvo_aacenc @ 03bb0200] Unable to set encoding parameters

So I try to copy the audio codec (not sure if this works for MP4...) with "-c:a copy" and I get this:

Stream #0:1(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 7.1 (24 bit), 9216 kb/s (default)
Metadata:
  creation_time   : 2017-03-14 21:48:34
  handler_name    : Apple Alias Data Handler Stream mapping:   Stream #0:2 -> #0:0 (mpeg2video (native) -> h264 (libx264))   Stream

0:0 -> #0:1 (copy) Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument

What is going on here?

Answer 1

Your AAC encoder only supports 2 channels. Add -ac 2.

But actually, you should upgrade your FFmpeg. It's very old, the VO AAC encoder is no longer available as the native encoder is better and supports 7.1 CH audio, so no downmixing required.