lavc/libaribcaption.c: add ARIB caption decoder using libaribcaption

This patch add another ARIB caption decoder using libaribcaption
external library.

Unlike libaribb24, it supports 3 types of subtitle outputs:
* text: plain text
* ass: ASS formatted text
* bitmap: bitmap image

Default subtitle type is ass as same as libaribb24.
Advantages compared with libaribb24 on ASS subtitle are:
* Subtitle positioning.
* Multi-rect subtitle: some captions are displayed at different
  position at a time.
* More stability and reproducibility.

To compile with this feature:
* libaribcaption external library has to be pre-installed.
* configure with `--enable-libaribcaption` option.

`--enable-libaribb24` and `--enable-libaribcaption` options are
not exclusive. If both enabled, libaribcaption precedes as
order listed in `libavcodec/allcodecs.c`.

Signed-off-by: rcombs <rcombs@rcombs.me>
This commit is contained in:
TADANO Tokumei 2023-02-23 19:17:15 +09:00 committed by rcombs
parent 38bb137e99
commit b6138633cd
6 changed files with 1329 additions and 0 deletions

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@ -2,6 +2,7 @@ Entries are sorted chronologically from oldest to youngest within each release,
releases are sorted from youngest to oldest.
version <next>:
- libaribcaption decoder
version 6.0:
- Radiance HDR image support

configure vendored
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@ -218,6 +218,7 @@ External library support:
--enable-lcms2 enable ICC profile support via LittleCMS 2 [no]
--enable-libaom enable AV1 video encoding/decoding via libaom [no]
--enable-libaribb24 enable ARIB text and caption decoding via libaribb24 [no]
--enable-libaribcaption enable ARIB text and caption decoding via libaribcaption [no]
--enable-libass enable libass subtitles rendering,
needed for subtitles and ass filter [no]
--enable-libbluray enable BluRay reading using libbluray [no]
@ -1805,6 +1806,7 @@ EXTERNAL_LIBRARY_LIST="
@ -3331,6 +3333,7 @@ libaom_av1_decoder_deps="libaom"
@ -6569,6 +6572,7 @@ enabled libaom && require_pkg_config libaom "aom >= 1.0.0" aom/aom_co
enabled libaribb24 && { check_pkg_config libaribb24 "aribb24 > 1.0.3" "aribb24/aribb24.h" arib_instance_new ||
{ enabled gpl && require_pkg_config libaribb24 aribb24 "aribb24/aribb24.h" arib_instance_new; } ||
die "ERROR: libaribb24 requires version higher than 1.0.3 or --enable-gpl."; }
enabled libaribcaption && require_pkg_config libaribcaption "libaribcaption >= 0.1.0" "aribcaption/aribcaption.h" aribcc_context_alloc
enabled lv2 && require_pkg_config lv2 lilv-0 "lilv/lilv.h" lilv_world_new
enabled libiec61883 && require libiec61883 libiec61883/iec61883.h iec61883_cmp_connect -lraw1394 -lavc1394 -lrom1394 -liec61883
enabled libass && require_pkg_config libass "libass >= 0.11.0" ass/ass.h ass_library_init

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@ -353,6 +353,156 @@ Enabled by default.
@end table
@section libaribcaption
Yet another ARIB STD-B24 caption decoder using external @dfn{libaribcaption}
Implements profiles A and C of the Japanse ARIB STD-B24 standard,
Brazilian ABNT NBR 15606-1, and Philippines version of ISDB-T.
Requires the presence of the libaribcaption headers and library
(@url{https://github.com/xqq/libaribcaption}) during configuration.
You need to explicitly configure the build with @code{--enable-libaribcaption}.
If both @dfn{libaribb24} and @dfn{libaribcaption} are enabled, @dfn{libaribcaption}
decoder precedes.
@subsection libaribcaption Decoder Options
@table @option
@item -sub_type @var{subtitle_type}
Specifies the format of the decoded subtitles.
@table @samp
@item bitmap
Graphical image.
@item ass
ASS formatted text.
@item text
Simple text based output without formatting.
@end table
The default is @dfn{ass} as same as @dfn{libaribb24} decoder.
Some present players (e.g., @dfn{mpv}) expect ASS format for ARIB caption.
@item -caption_encoding @var{encoding_scheme}
Specifies the encoding scheme of input subtitle text.
@table @samp
@item auto
Automatically detect text encoding.
@item jis
8bit-char JIS encoding defined in ARIB STD B24.
This encoding used in Japan for ISDB captions.
@item utf8
UTF-8 encoding defined in ARIB STD B24.
This encoding is used in Philippines for ISDB-T captions.
@item latin
Latin character encoding defined in ABNT NBR 15606-1.
This encoding is used in South America for SBTVD / ISDB-Tb captions.
@end table
The default is @dfn{ass} as same as @dfn{libaribb24} decoder.
Some present players (e.g., @dfn{mpv}) expect ASS format for ARIB caption.
@item -font @var{font_name[,font_name2,...]}
Specify comma-separated list of font family names to be used for @dfn{bitmap}
or @dfn{ass} type subtitle rendering.
Only first font name is used for @dfn{ass} type subtitle.
If not specified, use internaly defined default font family.
@item -ass_single_rect @var{boolean}
ARIB STD-B24 specifies that some captions may be displayed at different
positions at a time (multi-rectangle subtitle).
Since some players (e.g., old @dfn{mpv}) can't handle multiple ASS rectangles
in a single AVSubtitle, or multiple ASS rectangles of indeterminate duration
with the same start timestamp, this option can change the behavior so that
all the texts are displayed in a single ASS rectangle.
The default is @var{false}.
If your player cannot handle AVSubtitles with multiple ASS rectangles properly,
set this option to @var{true} or define @env{ASS_SINGLE_RECT=1} to change
default behavior at compilation.
@item -replace_fullwidth_ascii @var{boolean}
Specify whether to replace MSZ (Middle Size, half width) fullwidth
alphanumerics with halfwidth alphanumerics.
The default is @var{true}.
@item -force_outline_text @var{boolean}
Specify whether always render outline text for all characters regardless of
the indication by charactor style.
The default is @var{false}.
@item -outline_width @var{number} (0.0 - 3.0)
Specify width for outline text, in dots (relative).
The default is @var{1.5}.
@item -ignore_background @var{boolean}
Specify whether to ignore background color rendering.
The default is @var{false}.
@item -ignore_ruby @var{boolean}
Specify whether to ignore rendering for ruby-like (furigana) characters.
The default is @var{false}.
@item -replace_drcs @var{boolean}
Specify whether to render replaced DRCS characters as Unicode characters.
The default is @var{true}.
@item -canvas_size @var{image_size}
Specify the resolution of the canvas to render subtitles to; usually, this
should be frame size of input video.
This only applies when @code{-subtitle_type} is set to @var{bitmap}.
The libaribcaption decoder assumes input frame size for bitmap rendering as below:
PROFILE_A : 1440 x 1080 with SAR (PAR) 4:3
PROFILE_C : 320 x 180 with SAR (PAR) 1:1
@end enumerate
If actual frame size of input video does not match above assumption,
the rendered captions may be distorted.
To make the captions undistorted, add @code{-canvas_size} option to specify
actual input video size.
Note that the @code{-canvas_size} option is not required for video with
different size but same aspect ratio.
In such cases, the caption will be stretched or shrunk to actual video size
if @code{-canvas_size} option is not specified.
If @code{-canvas_size} option is specified with different size,
the caption will be stretched or shrunk as specified size with calculated SAR.
@end table
@subsection libaribcaption decoder usage examples
Display MPEG-TS file with ARIB subtitle by @code{ffplay} tool:
ffplay -sub_type bitmap MPEG.TS
@end example
Display MPEG-TS file with input frame size 1920x1080 by @code{ffplay} tool:
ffplay -sub_type bitmap -canvas_size 1920x1080 MPEG.TS
@end example
Embed ARIB subtitle in transcoded video:
ffmpeg -sub_type bitmap -i src.m2t -filter_complex "[0:v][0:s]overlay" -vcodec h264 dest.mp4
@end example
@section dvbsub
@subsection Options

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@ -1079,6 +1079,7 @@ OBJS-$(CONFIG_PCM_MULAW_AT_ENCODER) += audiotoolboxenc.o
OBJS-$(CONFIG_LIBAOM_AV1_DECODER) += libaomdec.o libaom.o
OBJS-$(CONFIG_LIBAOM_AV1_ENCODER) += libaomenc.o libaom.o
OBJS-$(CONFIG_LIBARIBB24_DECODER) += libaribb24.o ass.o
OBJS-$(CONFIG_LIBARIBCAPTION_DECODER) += libaribcaption.o ass.o

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@ -759,6 +759,8 @@ extern const FFCodec ff_pcm_mulaw_at_decoder;
extern const FFCodec ff_qdmc_at_decoder;
extern const FFCodec ff_qdm2_at_decoder;
extern FFCodec ff_libaom_av1_encoder;
/* preferred over libaribb24 */
extern const FFCodec ff_libaribcaption_decoder;
extern const FFCodec ff_libaribb24_decoder;
extern const FFCodec ff_libcelt_decoder;
extern const FFCodec ff_libcodec2_encoder;

libavcodec/libaribcaption.c Normal file

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