[FFmpeg-user] eac3 encoding

Moritz Barsnick barsnick at gmx.net
Mon Feb 13 23:57:07 EET 2017

On Mon, Feb 13, 2017 at 15:49:34 -0600, Mike Brown wrote:
> > I don't see any restriction in the code, and the standard doesn't seem
> > to imply any restriction either:
> Thanks.  I failed to look at dolby.com, but still needed to know if there
> were any restrictions in the code.

Sorry, I failed to see the restriction. ffmpeg will tell you if you
happen to enter an illegal one:

At 48k samplerate:
[eac3 @ 0xbe08920] invalid bit rate. must be 3008 to 6144000 for this sample rate
At 44.1k samplerate:
[eac3 @ 0xb9f3b40] invalid bit rate. must be 2768 to 5644800 for this sample rate

The actual formula is:
            max_br = 2048 * s->sample_rate / frame_samples * 16;
            min_br = ((s->sample_rate + (frame_samples-1)) / frame_samples) * 16;

I assume it is a restriction of the codec (of how it is defined), not
of the encoder.


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