[FFmpeg-devel] [PATCH 0/2] ARIB STD-B24 caption decoding using libaribb24

[Jan Ekström]

On Fri, Feb 8, 2019 at 2:38 AM Jan Ekström <jeebjp at gmail.com> wrote:
>
> On Sat, Feb 2, 2019 at 3:31 PM Jan Ekström <jeebjp at gmail.com> wrote:
> >
> > A decoder wrapper for the libaribb24 library found in various
> > distributions and currently utilized by VLC.
> >
> > Requires GPLv3 with the current most recent release, but as the
> > current library master is LGPLv3, any newer releases will require
> > only LGPLv3.
> >
> > If the library is not found in your distribution, it is available at:
> > https://github.com/nkoriyama/aribb24
> >
> > A test sample can be found at:
> > https://kuroko.fushizen.eu/samples/arib_captions_colors_positioning_ruby_subpics.ts
> >
> > An example of how the decoded output currently looks can be found at:
> > https://megumin.fushizen.eu/screenshots/arib_subs/mpv-shot0004.png
> >
> > I will proceed to making a FATE test as soon as I figure out the simplest
> > way to limit an MPEG-TS stream to some PIDs without doing full remuxing.
> > (I think dvblast has something like this so I might take a look at that)
> >
> > The decoded subtitles might or might not have durations set, so with
> > ffmpeg.c `-fix_sub_duration` is required.
> >
> > Regarding positioning:
> >
> > I have an initial version of positioning implemented, but unfortunately
> > it requires multiple subtitle lines per AVSubtitle, and many applications
> > seem to fail at handling them, including the encoding portions of
> > libavformat/libavcodec (all lines end up concatenated into a single line, even
> > though that is 100% invalid as there is a header included).
> >
> > Thus I have decided to post the first version out now, as when the ruby
> > blocks are not included as a distraction, single-line output seems to be
> > fine and readable/enjoyable.
> >
> > Best regards,
> > Jan
> >
> > Jan Ekström (2):
> >   add libaribb24 ARIB STD-B24 caption decoder
> >   lavf/mpegts: add reading of ARIB data coding descriptor
> >
> >  Changelog               |   1 +
> >  configure               |   7 +
> >  doc/decoders.texi       |  25 +++
> >  libavcodec/Makefile     |   1 +
> >  libavcodec/allcodecs.c  |   1 +
> >  libavcodec/avcodec.h    |   4 +
> >  libavcodec/codec_desc.c |   9 +-
> >  libavcodec/libaribb24.c | 378 ++++++++++++++++++++++++++++++++++++++++
> >  libavcodec/profiles.c   |   6 +
> >  libavcodec/profiles.h   |   1 +
> >  libavcodec/version.h    |   2 +-
> >  libavformat/mpegts.c    |  47 +++++
> >  libavformat/version.h   |   2 +-
> >  13 files changed, 481 insertions(+), 3 deletions(-)
> >  create mode 100644 libavcodec/libaribb24.c
> >
> > --
> > 2.20.1
> >
>
> I really don't like to do this because I really like consensus... But
> now that I know that the disagreement that was had about this patch
> set was not a blocking one, I would like to move forward with my
> ARIB-related work (of which this was part 1). As I have addressed all
> the technical comments that I have received regarding the patches in
> this set, if any more doesn't come within the next 24 or so hours or
> so I would like to start pushing this in as a "reference" decoder for
> this format against which a future internal implementation can be
> compared against.
>

As there have been no further objections, I will be pushing this patch
set and enabling demuxing of ARIB captions with FFmpeg, as well as
decoding with libaribb24 (until an internal decoder is implemented). I
tried to call out for comments to see if anyone had *something* to say
about this patch set during the past two days - but none were
negative.

As another positive sign, the author of this library has recently
re-activated, so while it is likely that the library might move under
the VideoLAN umbrella in the longer term, we should be able to receive
clarification regarding some things.

Thank you,
Jan