[FFmpeg-devel] [PATCH v6 1/3] avcodec: add flags for packets with top/bottom field

Rostislav Pehlivanov atomnuker at gmail.com
Wed May 23 18:46:17 EEST 2018


On 23 May 2018 at 16:18, wm4 <nfxjfg at googlemail.com> wrote:

> On Tue, 22 May 2018 17:19:35 -0400 (EDT)
> Patrick Keroulas <patrick.keroulas at savoirfairelinux.com> wrote:
>
> > ----- Original Message -----
> > > From: "Rostislav Pehlivanov" <atomnuker at gmail.com>
> > > To: "FFmpeg development discussions and patches" <
> ffmpeg-devel at ffmpeg.org>
> > > Sent: Friday, May 18, 2018 5:28:42 PM
> > > Subject: Re: [FFmpeg-devel] [PATCH v6 1/3] avcodec: add flags for
> packets with top/bottom field
> >
> > > On 18 May 2018 at 22:17, wm4 <nfxjfg at googlemail.com> wrote:
> >
> >
> >
> > > > But I think a new side data type would be much saner. We could even
> > > > just make it something generic, like AV_PKT_DATA_ANCILLARY or
> > > > something. It's apparently just packet data which somehow couldn't go
> > > > into the packet data.
> >
> >
> > > I agree, a generic ancillary side data type sounds better. It would
> have to
> > > be handled the same way as mastering metadata (e.g. to allocate it
> you'd
> > > need to use a separate function), since the size of the data struct
> can't
> > > be part of the API if we intend to add fields later.
> > > Patrick, if you're okay with that you should submit a patch which bases
> > > such side data on libavutil/mastering_display_metadata.h/.c
> >
> > No problem for transmitting field flags through side data. But the given
> > example (libavutil/mastering_display_metadata.h/.c) attaches data to
> > AVFrame, not AVPacket, so I'm not sure where to place this separate
> > allocator function. Do you recommend to create a new
> > libavcodec/ancillary.c/h utility?
>
> The example you mentioned exists for AVPacket too (it's just not easy
> to see how it can end up in AVPacket, because no demuxer does that
> directly).
>
> Anyway, ancillary side data would just be an untyped byte array, so I
> don't think it needs any helpers. Just an addition to the packet side
> data enum (I think it's somewhere in avcodec.h).
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I'd rather have it as a well defined typed array rather than a bunch of
bytes. Otherwise we'd start sending unknown side data info and users
wouldn't know what to do with it.


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