[libav-tools] AAC encoded files show "0 kbps" average bitrate.

Luca Barbato lu_zero at gentoo.org
Thu Oct 4 21:15:58 CEST 2012

On 10/04/2012 12:27 PM, Oliver Hookins wrote:
>> Which player has problems? Picking the patch now btw.
> JWplayer (http://www.longtailvideo.com/players). My main use case is
> progressive-download playback over the web so I have been doing all my
> testing over HTTP. Specifically though, since AAC support in browsers
> is patchy at best, most players like this one just use Flash to play
> it back. Flash in this case is reporting that the net stream has
> closed, before it has even started playing. This makes me think that
> it is receiving some information it can't handle in the stream, or
> that it doesn't understand.

If you use flowplayer or you just load it what happens?

> Again, this only seems to happen with files encoded by avconv in MP4
> container format, regardless of AAC codec chosen. The Nero AAC encoded
> files work perfectly in any command line player or the Flash-based web
> players.

According to 14496-1:2010 DecoderConfigDescriptor:
 avgBitrate – is the average bitrate in bits per second of this
 elementary stream. For streams with variable bitrate this value
 shall be set to zero.

(thanks to our mp4 experts)

So either flash is out of specification or there is something with the
specific player... (or the interpretation of the paragraph could be


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