[FFmpeg-devel] [PATCH] Add rc_max_rate to ffprobe stream output

Michael Niedermayer michaelni at gmx.at
Sun Jun 8 14:10:12 CEST 2014

On Sun, Jun 08, 2014 at 12:57:28PM +0200, Stefano Sabatini wrote:
> On date Wednesday 2014-06-04 18:49:18 +0000, Carl Eugen Hoyos encoded:
> > Stefano Sabatini <stefasab <at> gmail.com> writes:
> > 
> > > > +    if (dec_ctx->rc_max_rate > 0) print_val 
> > > ("max_bit_rate", dec_ctx->rc_max_rate, unit_bit_per_second_str);
> > > > +    else                       print_str_opt("max_bit_rate", "N/A");
> > > 
> > > AVCodecContext.rc_max_rate is an encoding parameter
> > 
> > The documentation is now fixed.
> ffmpeg-codecs(1)
>        maxrate integer (encoding,audio,video)
>            Set max bitrate tolerance (in bits/s). Requires bufsize to be set.

> So the question still stands: what's the use case for this?

the max rate is part of the paremeters needed for creating correct
valid VBR/CBR mpeg*/h26*. Which can be especially important if you
care about spec compliance or supporting hw players. or intent to
transmit the data over a channel with low latency that doesnt have
infinite bandwidth and want to have a proof it will work and not just
hope it will ...

ok above is talk about encoding but

concrete use cases, you have some stream, be that clasical broadcast,
internet streaming stuff, or some kind of storage media.
and you want to create a similar compatible stream, you need to know
the buffer sizes and max rate for that.
ffprobe displaying what existing streams use should be helpfull in
choosing valid parameters if you have no access to the proper specs
and its not one of the common formats like DVD/VCD  ...

> Also I suspect we're abusing maxrate for something which is really
> MPEG video specific.
> -- 
> FFmpeg = Fostering Forgiving Magical Ponderous Enlightened Gadget
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <https://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20140608/c4cf67ad/attachment.asc>

More information about the ffmpeg-devel mailing list