[FFmpeg-devel] [PATCH] ffmpeg: raise level for message printed in case of auto-select pixel format

Michael Niedermayer michaelni at gmx.at
Wed Jul 31 00:40:16 CEST 2013

On Tue, Jul 30, 2013 at 11:48:37PM +0200, Nicolas George wrote:
> Le duodi 12 thermidor, an CCXXI, Michael Niedermayer a écrit :
> > i think that 90% of the users dont know if they want 420 or
> > 444 h264.
> They do not know if they want 420 or 444, I grant you that of course, but I
> believe they know whether they want the highest possible quality or
> compatibility with crappy players. They just need to learn that they can not
> have both.
> > IMO software (and hardware) should just work, not _require_
> > complicated manual tweaking for the common use cases.
> It is not possible in all cases. You can use scissors without manual
> tweaking, because cutting paper is a simple task. You can not expect to fly
> a plane without manual tweaking.
> Pixel format selection is a pebble on the beach of all things that have to
> be taken care of to get proper results in video transcoding: resolution (and
> aspect ratio! how many videos with wrong aspect ratio on the loose?),
> deinterleaving (how many videos with ugly comb effect?), codec,
> bitrate/quality selection, container format, etc.
> > if it fails with a warning that many users accessing it through a GUI
> > wont see and thuse who do see it and dont miss it maybe wont fully
> > understand it without educating themselfs on it to make a decission.

> That is the GUI's author's problem.

> > Its a bit as if when calling someone over the phone the phone would
> > stay silent and display a message that it choose a protocol that might
> > not be supported but would then be higher quality if it is supported
> > and require manual intervention to get a working phone connection.
> Your comparison is not valid, because the phone can negotiate the protocol
> on the fly. ffmpeg can not know that you intend to use the file with your
> stepmother's crappy player, and even less whether said player supports 444.

The idea was that "assume the phone could not negotiate it and had
to choose"

Its a question about what the default should be


> It is a shame, but we just can not have it both ways. Getting the users
> state their intent is the best solution.

there a fileformat, theres the -target and theres the codec profile
and level.
These should provide sufficient informatio about what the target
player kind would be and its ffmpegs job to figure out from that
what pixel format can be used. Its not the users job to know if a
ipod can do 444 or a dvd allows 422 mpeg2. he just specifies what
he is encoding for and if our selection of formats/targets/profiles
codecs isnt enough then it could be extended.


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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