[FFmpeg-user] stereo downmix error aac HEv2

[Sean Darcy]

On 03/14/2014 06:19 PM, Sean Darcy wrote:
> stripping audio from a VOB , I was trying to reencode to a lower
> bitrate, and downmix to mono. git March 13.
>
>   This worked fine:
>
> ffmpeg -i /mnt/dvd/VIDEO_TS/VTS_01_1.VOB -vn -c:a libfdk_aac -b:a 48k
> -ac 1  1-Talk-show-ac1-48testk.m4a
>
> and I can use HEv2 if I don't downmix:
>
> ffmpeg -i /mnt/dvd/VIDEO_TS/VTS_01_1.VOB -vn -c:a libfdk_aac -profile:a
> aac_he_v2 -b:a 48k  1-Talk-he-ac2-48testk.m4a
>
> But:
>
> ffmpeg -i /mnt/dvd/VIDEO_TS/VTS_01_1.VOB -vn -c:a libfdk_aac -profile:a
> aac_he_v2 -b:a 48k -ac 1 1-Talk-he-ac1-48testk.m4a
> ffmpeg version 2.2.git Copyright (c) 2000-2014 the FFmpeg developers
>    built on Mar 13 2014 15:33:24 with gcc 4.8.2 (GCC) 20131212 (Red Hat
> 4.8.2-7)
>    configuration: --prefix=/usr --bindir=/usr/bin
> --datadir=/usr/share/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man
> --shlibdir=/usr/lib64 --extra-cflags='-Ofast -march=native -mtune=native
> -fopenmp -fomit-frame-pointer -pipe' --enable-avresample --enable-static
> --enable-shared --enable-gray --enable-gpl --enable-nonfree
> --enable-version3 --enable-postproc --enable-avfilter
> --enable-avresample --enable-pthreads --enable-x11grab --enable-gray
> --enable-vaapi --enable-hardcoded-tables --enable-libaacplus
> --enable-avisynth --enable-frei0r --enable-libfdk-aac --enable-libgsm
> --enable-libmp3lame --enable-libopenjpeg --enable-libopus
> --enable-librtmp --enable-libschroedinger --enable-libspeex
> --enable-libtheora --enable-libvo-aacenc --enable-libvorbis
> --enable-libvpx --enable-libx264 --enable-libxvid --enable-zlib
> --disable-debug --cpu=amdfam10 --arch=x86_64 --enable-pic
> --enable-libopencv --enable-openssl
>    libavutil      52. 66.101 / 52. 66.101
>    libavcodec     55. 52.102 / 55. 52.102
>    libavformat    55. 34.101 / 55. 34.101
>    libavdevice    55. 11.100 / 55. 11.100
>    libavfilter     4.  3.100 /  4.  3.100
>    libavresample   1.  2.  0 /  1.  2.  0
>    libswscale      2.  5.101 /  2.  5.101
>    libswresample   0. 18.100 /  0. 18.100
>    libpostproc    52.  3.100 / 52.  3.100
> Input #0, mpeg, from '/mnt/dvd/VIDEO_TS/VTS_01_1.VOB':
>    Duration: 00:07:22.24, start: 0.280633, bitrate: 19421 kb/s
>      Stream #0:0[0x1bf]: Data: dvd_nav_packet
>      Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv), 720x480
> [SAR 8:9 DAR 4:3], max. 3000 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
>      Stream #0:2[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
> [libfdk_aac @ 0x12b3300] Unable to initialize the encoder: SBR library
> initialization error
> Output #0, ipod, to '1-Talk-he-ac1-48testk.m4a':
>      Stream #0:0: Audio: aac (HE-AACv2), 48000 Hz, mono, s16, 48 kb/s
> Stream mapping:
>    Stream #0:2 -> #0:0 (ac3 -> libfdk_aac)
> Error while opening encoder for output stream #0:0 - maybe incorrect
> parameters such as bit_rate, rate, width or height
>
> Thanks for any help.
>
> sean

Oddly, this works:

ffmpeg -i /mnt/dvd/VIDEO_TS/VTS_01_1.VOB -vn -c:a libfdk_aac -profile:a 
aac_he_v2 -b:a 48k -ac 2 1-Talk-he-ac1-48testk.m4a

So it's not just a problem passing the audio channels argument.

sean