Re: [FFmpeg-devel] [PATCH 8/8] Make mime-type award a bonus probe score

[Michael Niedermayer <michael@niedermayer.cc>]

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Hi Tomas

On Wed, Feb 05, 2025 at 03:24:24PM +0100, Tomas Härdin wrote:
> Seems reasonable to me and passes FATE
> 
> /Tomas

>  avformat.h   |    2 +-
>  format.c     |    8 ++++----
>  libopenmpt.c |    2 +-
>  3 files changed, 6 insertions(+), 6 deletions(-)
> 01f04f79202640330d6be91b0215f92f14d1845a  0008-Make-mime-type-award-a-bonus-probe-score.patch
> From ecc3459990f2871fd907f96fe66362b8fea41bd8 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?Peter=20Zeb=C3=BChr?= <peterz@spotify.com>
> Date: Tue, 21 Nov 2023 14:16:49 +0100
> Subject: [PATCH 8/8] Make mime-type award a bonus probe score
> 
> This changes the default behaviour of ffmpeg where content-type headers
> on an input gives an absolut probe score (of 75) to instead give a bonus
> score (of 30). This gives the probe a better chance to arrive at the
> correct format by (hopefully) giving a large enough bonus to push edge
> cases in the right direction (MPEG-PS vs MP3, I am looking at you) while
> also not adversly punishing clearer cases (raw ADTS marked as
> "audio/mpeg" for example).
> 
> This patch was regression tested against 20 million recent podcast
> submissions (after content-type propagation was added to
> original-storage), and 50k Juno vodcasts submissions (dito). No adverse
> effects observed (but the bonus may still need tweaking if other edge
> cases are detected in production).
> ---
>  libavformat/avformat.h   | 2 +-
>  libavformat/format.c     | 8 ++++----
>  libavformat/libopenmpt.c | 2 +-
>  3 files changed, 6 insertions(+), 6 deletions(-)

what is the score ?
a higher score means more likely but how much more ?
maybe we should come up with a more formal definition
like that score is the number of bits of entropy that where checked or
something like that.
in such a framework, adding 30 for a mime type match would probably
make sense

without such a framework, adding 30 to a abstract score is hard to
review
beyond that, i dont see anything breaking from this but then i
dont think we have real tests for mime types

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Freedom in capitalist society always remains about the same as it was in
ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin

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