[MPlayer-users] Re: Mencoder: are the displayed bitrates accurate?

[Tobias Diedrich]

I wrote:

> The mplex manpage states 46KB for VCD and 230KB for SVCD.
> Tsunami MPEG encoder templates default to 224KB for DVD, 112KB for SVCD
> and 40KB for VCD.

If vrc_buf_size is not set, libavcodec calculates
vbv_buffer_size as follows:

/* VBV calculation: Scaled so that a VCD has the proper VBV size of 40
 * kilobytes */
vbv_buffer_size = (( 20 * s->bit_rate) / (1151929 / 2)) * 8 * 1024;
vbv_buffer_size = (vbv_buffer_size + 16383) / 16384;

AFAICS s->bit_rate maps to mplayer's vbitrate option (But is in bits per
second).

So for 1151929bps we get 40KB, for 3225401.2bps we get 112KB and for
6450802.4bps we get 224KB.

The libavcodec comment also suggests that the values in the mplex
manpage may be incorrect and the values used by Tsunami may be the
correct ones.

-- 
Tobias						PGP: http://9ac7e0bc.2ya.com
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