Re: [FFmpeg-devel] [PATCH 2/2] lavfi/setpts: introduce rand() function in expression

From: Stefano Sabatini <stefasab@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 2/2] lavfi/setpts: introduce rand() function in expression
Date: Tue, 2 Jan 2024 22:12:44 +0100
Message-ID: <ZZR8TAnTYU+K7ZS7@mariano> (raw)
In-Reply-To: <ZY6yrobW35Tr8wIt@mariano>

On date Friday 2023-12-29 12:51:10 +0100, Stefano Sabatini wrote:
> On date Thursday 2023-12-28 22:25:08 +0100, Michael Niedermayer wrote:
> > On Thu, Dec 28, 2023 at 07:49:18PM +0100, Stefano Sabatini wrote:
> > > On date Thursday 2023-12-28 16:00:57 +0100, Stefano Sabatini wrote:
> > > > On date Thursday 2023-12-28 12:02:59 +0100, Andreas Rheinhardt wrote:
> > > > > Stefano Sabatini:
> > > > > > This is useful to simulate random jitter.
> > > > > > ---
> > > > > >  Changelog            |  1 +
> > > > > >  doc/filters.texi     | 10 +++++++++-
> > > > > >  libavfilter/setpts.c | 39 +++++++++++++++++++++++++++++++++------
> > > > > >  3 files changed, 43 insertions(+), 7 deletions(-)
> > > [...]
> > > > > Why is this added here and not in lavu/eval so that it is available with
> > > > > all expressions?
> > > > 
> > > > There is no specific reason. Sometimes you need to have a control over
> > > > the seed, in this case you need to provide the PRNG context.
> > > > 
> > > > For the general case, probably we can place a global LFG in the eval
> > > > module and fetch its generated values.
> > > 
> > > Another possible solution in attachment, leveraging the same affine
> > > PRNG used in random(). For other use cases you might need to use a
> > > high-quality PRNG and this might not be good enough.
> > 
> > >  eval.c |   18 +++++++++++++++---
> > >  1 file changed, 15 insertions(+), 3 deletions(-)
> > > 94413dcc88e3046b4987715f6c152aeb1c24c703  0001-lavu-eval-add-randomi-function-to-compute-random-val.patch
> > > From 4dc5213b0913a2585f75dfd03b497ca2efc093de Mon Sep 17 00:00:00 2001
> > > From: Stefano Sabatini <stefasab@gmail.com>
> > > Date: Thu, 28 Dec 2023 19:09:22 +0100
> > > Subject: [PATCH] lavu/eval: add randomi function to compute random value in
> > >  interval
> > 
> > probably ok if this is usefull
> > 
> > thx
> 
> Will apply the edited patch in a few days if I see no comments.

Applied.
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