[vlc-devel] [RFC PATCH 00/13] Expose picture attachment through libvlc

[Thomas Guillem]

Hello,

This set looks very good to me. Just one point.

We need to ensure that demux modules don't update an attachment (asserts or document it).

Indeed, attachments are now read via VLC CORE API from any threads, so they can't be updated unless you add a mutex for each attachment.

On Fri, Nov 6, 2020, at 10:22, Hugo Beauzée-Luyssen wrote:
> This patchset is an RFC that aims at exposing picture attachments (at
> least) to users through libvlc
> This is initially motivated by the fact that we need to be able to
> handle various tracks belonging to the same album, but with different
> embedded artwork.
> Currently, VLC will cache embedded artworks as they are found in
> cachefolder/artist/date/album meaning that the first track artwork 
> will be cached, and later ones will be considered already cached, even
> though they are different.
> 
> Additionally, this introduces refcounting to the attachments, allowing
> us to save a deep copy every time the attachments are fetched. This
> could also allow us to fetch attachments using a unique identifier
> instead of their names, as the name unicity is currently no guaranteed
> 
> Hugo Beauzée-Luyssen (13):
>   input: Move attachment functions in their own source file
>   input: attachment: Add a private structure
>   input: Refcount attachments
>   mkv: Use input_attachment_t directly
>   mp4: Extract attachments once
>   input: Simplify AppendAttachment prototype
>   input: Compare attachments themselves when updating them
>   input: Remove now unused attachment_demux
>   input: Move attachment to input_item_t
>   input: Manage attachment through the item
>   core: Expose input_item_GetAttachments
>   lib: Add a picture from attachment constructor
>   lib: media: Expose attached pictures
> 
>  include/vlc/libvlc_media.h                   |   5 +
>  include/vlc_input.h                          |  49 +------
>  include/vlc_input_item.h                     |   7 +
>  lib/libvlc.sym                               |   1 +
>  lib/media.c                                  |  38 ++++++
>  lib/picture.c                                |  51 +++++++
>  lib/picture_internal.h                       |   2 +
>  modules/access/bluray.c                      |   6 +-
>  modules/codec/libass.c                       |   2 +-
>  modules/codec/subsusf.c                      |   2 +-
>  modules/demux/avformat/demux.c               |   6 +-
>  modules/demux/avi/avi.c                      |   4 +-
>  modules/demux/flac.c                         |   4 +-
>  modules/demux/mkv/demux.cpp                  |   2 -
>  modules/demux/mkv/demux.hpp                  |   5 +-
>  modules/demux/mkv/matroska_segment_parse.cpp |  37 +++---
>  modules/demux/mkv/mkv.cpp                    |   9 +-
>  modules/demux/mkv/mkv.hpp                    |  30 -----
>  modules/demux/mp4/attachments.c              |   5 +-
>  modules/demux/mp4/attachments.h              |   2 +-
>  modules/demux/mp4/mp4.c                      |  18 ++-
>  modules/demux/mpeg/ts.c                      |   4 +-
>  modules/demux/ogg.c                          |   4 +-
>  modules/text_renderer/freetype/freetype.c    |   8 +-
>  src/Makefile.am                              |   1 +
>  src/input/access.c                           |   5 +-
>  src/input/attachment.c                       |  90 +++++++++++++
>  src/input/es_out.c                           |   4 +-
>  src/input/input.c                            | 132 +++++--------------
>  src/input/input_internal.h                   |   9 --
>  src/input/item.c                             |  45 +++++++
>  src/input/meta.c                             |   4 +-
>  src/input/stream_memory.c                    |   2 +-
>  src/libvlccore.sym                           |   4 +
>  src/video_output/vout_subpictures.c          |   3 +-
>  35 files changed, 356 insertions(+), 244 deletions(-)
>  create mode 100644 src/input/attachment.c
> 
> -- 
> 2.28.0
> 
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