Loop and mix audio on video I want to mix audio on a video.
The video already has audio stream in it. I'm adding another one.

The new audio I'm adding is shorter than the video. So, I want to loop it as long as the video lasts.

So far, I'm doing this:

ffmpeg -y -i test.mp4 -stream_loop -1 -i bg_sound.mp3 -filter_complex "[0:a][1:a]amix=inputs=2:duration=longest[out]" -map 0:v -map [out] output.mp4


This adds the audio on the video, but does not loop it. I've also tried stream_loop with other integer options with no luck. The audio I'm adding ends and the rest of the video continues.

I need to loop my audio.

Here is the ffprobe result of my video:

   ffprobe version N-76452-ga97f1e7 Copyright (c) 2007-2015 the FFmpeg developers
   built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
   configuration: --prefix=/home/alfanso/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/alfanso/ffmpeg_build/include --extra-ldflags=-L/home/alfanso/ffmpeg_build/lib --bindir=/home/alfanso/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
   libavutil      55.  5.100 / 55.  5.100
   libavcodec     57. 14.100 / 57. 14.100
   libavformat    57. 14.100 / 57. 14.100
   libavdevice    57.  0.100 / 57.  0.100
   libavfilter     6. 14.101 /  6. 14.101
   libswscale      4.  0.100 /  4.  0.100
   libswresample   2.  0.100 /  2.  0.100
   libpostproc    54.  0.100 / 54.  0.100
   Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'localtest.mp4':
   Metadata:
       major_brand     : isom
       minor_version   : 512
       compatible_brands: isomiso2avc1mp41
       encoder         : Lavf56.40.101
       Duration: 00:06:53.97, start: 0.033333, bitrate: 179 kb/s
       Stream #0:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv444p, 1280x720, 45 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
   Metadata:
      handler_name    : VideoHandler
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 128 kb/s (default)
   Metadata:
      handler_name    : SoundHandler


I've also tried using different video and audio sources with the same result.
It works if you mix audio separately.

ffmpeg -y -i test.mp4 \
-f lavfi -i amovie=bg_sound.mp3:loop=55555 \
-filter_complex "[0:a][1:a]amerge, \
                 pan=stereo|c0=0.5*c0+0.5*c2|c1=0.5*c1+0.5*c3" \
output.flac