[FFmpeg-devel] [PATCH 1/4] libavformat/movenc: add dnxhr compatibility for apple players

[Michael Niedermayer]

On Mon, Jul 18, 2016 at 05:39:46PM -0700, Mark Reid wrote:
> On Jul 18, 2016 5:11 PM, "Michael Niedermayer" <michael at niedermayer.cc>
> wrote:
> >
> > On Mon, Jul 18, 2016 at 04:37:49PM -0700, Mark Reid wrote:
> > > On Sun, Jul 17, 2016 at 4:35 AM, Michael Niedermayer
> > > <michael at niedermayer.cc> wrote:
> > > > On Sat, Jul 16, 2016 at 07:37:36PM -0700, Mark Reid wrote:
> > > >> ---
> > > >>  libavcodec/dnxhddec.c |  3 +++
> > > >>  libavformat/movenc.c  | 19 ++++++++++++++-----
> > > >>  2 files changed, 17 insertions(+), 5 deletions(-)
> > > >
> > > > this should be split
> > > > a single patch changing both libs is a bit suspicous API wise
> > > >
> > > >
> > > >>
> > > >> diff --git a/libavcodec/dnxhddec.c b/libavcodec/dnxhddec.c
> > > >> index 5b60326..4c6f708 100644
> > > >> --- a/libavcodec/dnxhddec.c
> > > >> +++ b/libavcodec/dnxhddec.c
> > > >> @@ -204,6 +204,9 @@ static int dnxhd_decode_header(DNXHDContext
> *ctx, AVFrame *frame,
> > > >>      }
> > > >>
> > > >>      cid = AV_RB32(buf + 0x28);
> > > >> +    if (cid >= 1270 && cid <= 1274)
> > > >> +        ctx->avctx->codec_tag = MKTAG('A','V','d','h');
> > > >
> > > > codec_tag is documented as:
> > > > * - decoding: Set by user, will be converted to uppercase by
> libavcodec during init.
> > > >
> > > > this sets it in the decoder by libavcodec though
> > > >
> > >
> > > okay, in that case I'll have to remove the same thing from the encoder
> patch.
> > > I saw some other codecs doing it so I assumed it was okay.
> >
> > several encoders set codec_tag, and the docs are a bit unclear about
> > that ...
> > * - encoding: Set by user, if not then the default based on codec_id will
> be used.
> >
> > but i think no decoder sets it
> 
> The issue I'm attempting to solve here is that there are two tags for the
> same codec_id
> 
> AVdn for dnxhd
> AVdh for dnxhr (Note the H instead of N)
> 
> av_codec_get_tag always returns the first tag because of the order in
> isom.c ff_codec_movvideo_tags

how hard is it to find out which it is from AVPacket.data ?
if its easy then the mov muxer (is this the only that needs it?)
could just check that to find which it is
theres quite some existing code in ff_mov_write_packet() and
functions called from it which analyze packets to satisfy the mov/mp4
specs

but thats just a random idea,
dont listen to me if you have a cleaner/simpler/better solution
maybe the profile can be used and is always set ...



[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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