Re: [FFmpeg-devel] What is FFmpeg and what should it be

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] What is FFmpeg and what should it be
Date: Fri, 4 Aug 2023 19:09:18 +0200
Message-ID: <20230804170918.GQ7802@pb2> (raw)
In-Reply-To: <CAK+ULv50dt--qguxN19Vm+TEBy3y6059abYy8qGx=_De6=498w@mail.gmail.com>

[-- Attachment #1.1: Type: text/plain, Size: 2387 bytes --]

On Thu, Aug 03, 2023 at 04:04:23PM -0400, Kieran Kunhya wrote:
> On Thu, 3 Aug 2023, 15:25 Michael Niedermayer, <michael@niedermayer.cc>
> wrote:
> 
> > On Thu, Aug 03, 2023 at 02:24:04PM -0400, Kieran Kunhya wrote:
> > > >
> > > >
> > > > There are 2 things DAB and DVB both use mpeg ts
> > > >
> > >
> > > DAB does not use mpegts. It has several layers of it's own framing.
> >
> > Well, i stand corrected then. I saw it on the ML and in some spec but that
> > was about IP data in DAB or something it seems.
> >
> > but thats a good thing, because if the framing used is not MPEG-TS
> > there will probably be noone objecting to it being removed and not
> > output.
> >
> 
> What does this sentence even mean?

> The framing is there for a reason (to
> delimit programs amongst other things). You can't just remove it. It has
> layers that some users will want.

Everything is there for a reason.
Every part of mp4 has a use, still we extract the data and setup various
structs like AVStream, AVPacket, AVProgram and so on.
We do not return raw mp4/mov atoms
the seperation between programs in a stream of bits/bytes looses meaning
once the frames are in AVPackets with AVStream/AVProgram.
If there is more data in any framing that people want, theres a wide range
of ways to preserve and export that data.
OTOH outputting AAC in TS or AAC is other framing is painfull to handle
especially when it is muxed into something again. because it then needs
the right framing and even if it comes in as DAB framing and the output
wants DAB framing, it is unlikely everything in the framing will be correct
for the output.
The same is true for TS. I surely can take raw TS from 3 programs but if
i just take these and concatenate them into something that suppports TS
thats quite likely going to blow up somehow.
All this framing stuff should IMHO be "removed" on the demuxer side
usefull data be extracted and properly exported. And if anything
on the muxing side needs something similar it needed to rebuild it all.

I may be missing something but i dont think the raw framing is too usefull
to the user.

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If a bugfix only changes things apparently unrelated to the bug with no
further explanation, that is a good sign that the bugfix is wrong.

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]

[-- Attachment #2: Type: text/plain, Size: 251 bytes --]

_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".