[FFmpeg-user] audio-only flv over rtmp

[Moritz Barsnick]

On Mon, Aug 05, 2013 at 11:50:09 +0100, Christian Ebert wrote:
> FLV is Flash Video, so a missing video track does not make sense
> imho.

Are you sure? It's just "another" container format. If I use the tool myspace-dl
to dump MySpace's music tracks to disks (an RTMP "stream", dumped with
rtmpdump), it gives me something like this:

> ffprobe ~/Downloads/Upstrokes/Upstrokes\ -\ 15\ Punx.flv
ffprobe version 1.1.git Copyright (c) 2007-2013 the FFmpeg developers
  built on Jul  2 2013 23:02:05 with icc (ICC) 13.1.1 20130313
  configuration: --prefix=/usr/new/tools/video/install/ffmpeg/20130702 --enable-gpl --enable-version3 --enable-nonfree --disable-shared --enable-x11grab --enable-gnutls --enable-libcdio --enable-libfreetype --enable-libx264 --enable-libmp3lame --enable-openal --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libass --enable-libv4l2 --enable-libvidstab --enable-libfdk-aac --cc=icc --cxx=icpc --extra-ldflags='-L /usr/new/tools/video/install/x264/current/lib -L /usr/new/tools/video/install/fdk-aac/current/lib' --extra-cflags='-I /usr/new/tools/video/install/x264/current/include -I /usr/new/tools/video/install/fdk-aac/current/include'
  libavutil      52. 38.100 / 52. 38.100
  libavcodec     55. 18.100 / 55. 18.100
  libavformat    55. 11.100 / 55. 11.100
  libavdevice    55.  2.100 / 55.  2.100
  libavfilter     3. 77.101 /  3. 77.101
  libswscale      2.  3.100 /  2.  3.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
Input #0, flv, from '/usr/home/barsnick/Downloads/Upstrokes/Upstrokes - 15 Punx.flv':
  Metadata:
    moovPosition    : 1433058
    aacaot          : 2
    audiochannels   : 2
  Duration: 00:01:48.80, start: 0.000000, bitrate: 111 kb/s
    Stream #0:0: Audio: aac, 44100 Hz, stereo, fltp

That indicates that that container contains only audio. (Other tools
confirm this.) I have no idea whether that's considered a "live stream"
though, and whether that would change anything.

I'm not very firm with the simplicity of containers, but this header
description nicely hints that FLV can contain either video, audio, or
both (max one of each):
http://en.wikipedia.org/wiki/FLV#Header

Leo, have you tried pointing ffprobe both at your Radio Six stream and
your self-generated stream, to see what the difference is? Don't give
up! :-)

Moritz