add libaribb24 ARIB STD-B24 caption decoder

* Outputs ASS lines with basic coloring and font scaling for each
  given region.
* Sets the default style to the resolution of the subtitle plane
  (for example, 960x540 / 36pt font for profile A).
* Has options to:
  * Disable ruby text (which is coded as regions which have
    half-height text in libaribb24).
    Enabled by default as without positioning ruby text only
    confuses as it is usually coded in the beginning of the decoded
    subtitle line.
  * Set the working directory, in which libaribb24 will read
    configuration as well as into which it may save broadcast extra
    symbols as PNG.
    Unset by default.

The unconventional library check can be explained by the library's
current master branch being licensed as LGPLv3, but at the time of
writing the latest official release is still licensed under GPLv3.

Thus, one either has to wait for the following release, or enable
GPLv3.

1 files changed, 384 insertions, 0 deletions

diff --git a/libavcodec/libaribb24.c b/libavcodec/libaribb24.c
new file mode 100644
index 0000000000..bc0255286c
--- /dev/null
+++ b/libavcodec/libaribb24.c
@@ -0,0 +1,384 @@
+/*
+ * ARIB STD-B24 caption decoder using the libaribb24 library
+ * Copyright (c) 2019 Jan Ekström
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avcodec.h"
+#include "libavcodec/ass.h"
+#include "libavutil/log.h"
+#include "libavutil/opt.h"
+
+#include <aribb24/aribb24.h>
+#include <aribb24/parser.h>
+#include <aribb24/decoder.h>
+
+typedef struct Libaribb24Context {
+    AVClass *class;
+
+    arib_instance_t *lib_instance;
+    arib_parser_t *parser;
+    arib_decoder_t *decoder;
+
+    int read_order;
+
+    char        *aribb24_base_path;
+    unsigned int aribb24_skip_ruby;
+} Libaribb24Context;
+
+static unsigned int get_profile_font_size(int profile)
+{
+    switch (profile) {
+    case FF_PROFILE_ARIB_PROFILE_A:
+        return 36;
+    case FF_PROFILE_ARIB_PROFILE_C:
+        return 18;
+    default:
+        return 0;
+    }
+}
+
+static void libaribb24_log(void *p, const char *msg)
+{
+    av_log((AVCodecContext *)p, AV_LOG_INFO, "%s\n", msg);
+}
+
+static int libaribb24_generate_ass_header(AVCodecContext *avctx)
+{
+    unsigned int plane_width = 0;
+    unsigned int plane_height = 0;
+    unsigned int font_size = 0;
+
+    switch (avctx->profile) {
+    case FF_PROFILE_ARIB_PROFILE_A:
+        plane_width = 960;
+        plane_height = 540;
+        font_size = get_profile_font_size(avctx->profile);
+        break;
+    case FF_PROFILE_ARIB_PROFILE_C:
+        plane_width = 320;
+        plane_height = 180;
+        font_size = get_profile_font_size(avctx->profile);
+        break;
+    default:
+        av_log(avctx, AV_LOG_ERROR, "Unknown or unsupported profile set!\n");
+        return AVERROR(EINVAL);
+    }
+
+    avctx->subtitle_header = av_asprintf(
+             "[Script Info]\r\n"
+             "; Script generated by FFmpeg/Lavc%s\r\n"
+             "ScriptType: v4.00+\r\n"
+             "PlayResX: %d\r\n"
+             "PlayResY: %d\r\n"
+             "\r\n"
+             "[V4+ Styles]\r\n"
+
+             /* ASSv4 header */
+             "Format: Name, "
+             "Fontname, Fontsize, "
+             "PrimaryColour, SecondaryColour, OutlineColour, BackColour, "
+             "Bold, Italic, Underline, StrikeOut, "
+             "ScaleX, ScaleY, "
+             "Spacing, Angle, "
+             "BorderStyle, Outline, Shadow, "
+             "Alignment, MarginL, MarginR, MarginV, "
+             "Encoding\r\n"
+
+             "Style: "
+             "Default,"             /* Name */
+             "%s,%d,"               /* Font{name,size} */
+             "&H%x,&H%x,&H%x,&H%x," /* {Primary,Secondary,Outline,Back}Colour */
+             "%d,%d,%d,0,"          /* Bold, Italic, Underline, StrikeOut */
+             "100,100,"             /* Scale{X,Y} */
+             "0,0,"                 /* Spacing, Angle */
+             "%d,1,0,"              /* BorderStyle, Outline, Shadow */
+             "%d,10,10,10,"         /* Alignment, Margin[LRV] */
+             "0\r\n"                /* Encoding */
+
+             "\r\n"
+             "[Events]\r\n"
+             "Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text\r\n",
+             !(avctx->flags & AV_CODEC_FLAG_BITEXACT) ? AV_STRINGIFY(LIBAVCODEC_VERSION) : "",
+             plane_width, plane_height,
+             ASS_DEFAULT_FONT, font_size, ASS_DEFAULT_COLOR,
+             ASS_DEFAULT_COLOR, ASS_DEFAULT_BACK_COLOR, ASS_DEFAULT_BACK_COLOR,
+             -ASS_DEFAULT_BOLD, -ASS_DEFAULT_ITALIC, -ASS_DEFAULT_UNDERLINE,
+             ASS_DEFAULT_BORDERSTYLE, ASS_DEFAULT_ALIGNMENT);
+
+    if (!avctx->subtitle_header)
+        return AVERROR(ENOMEM);
+
+    avctx->subtitle_header_size = strlen(avctx->subtitle_header);
+
+    return 0;
+}
+
+static int libaribb24_init(AVCodecContext *avctx)
+{
+    Libaribb24Context *b24 = avctx->priv_data;
+    void(* arib_dec_init)(arib_decoder_t* decoder) = NULL;
+    int ret_code = AVERROR_EXTERNAL;
+
+    if (!(b24->lib_instance = arib_instance_new(avctx))) {
+        av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24!\n");
+        goto init_fail;
+    }
+
+    if (b24->aribb24_base_path) {
+        av_log(avctx, AV_LOG_INFO, "Setting the libaribb24 base path to '%s'\n",
+               b24->aribb24_base_path);
+        arib_set_base_path(b24->lib_instance, b24->aribb24_base_path);
+    }
+
+    arib_register_messages_callback(b24->lib_instance, libaribb24_log);
+
+    if (!(b24->parser = arib_get_parser(b24->lib_instance))) {
+        av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24 PES parser!\n");
+        goto init_fail;
+    }
+    if (!(b24->decoder = arib_get_decoder(b24->lib_instance))) {
+        av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24 decoder!\n");
+        goto init_fail;
+    }
+
+    switch (avctx->profile) {
+    case FF_PROFILE_ARIB_PROFILE_A:
+        arib_dec_init = arib_initialize_decoder_a_profile;
+        break;
+    case FF_PROFILE_ARIB_PROFILE_C:
+        arib_dec_init = arib_initialize_decoder_c_profile;
+        break;
+    default:
+        av_log(avctx, AV_LOG_ERROR, "Unknown or unsupported profile set!\n");
+        ret_code = AVERROR(EINVAL);
+        goto init_fail;
+    }
+
+    arib_dec_init(b24->decoder);
+
+    if (libaribb24_generate_ass_header(avctx) < 0) {
+        ret_code = AVERROR(ENOMEM);
+        goto init_fail;
+    }
+
+    return 0;
+
+init_fail:
+    if (b24->decoder)
+        arib_finalize_decoder(b24->decoder);
+
+    if (b24->lib_instance)
+        arib_instance_destroy(b24->lib_instance);
+
+    return ret_code;
+}
+
+static int libaribb24_close(AVCodecContext *avctx)
+{
+    Libaribb24Context *b24 = avctx->priv_data;
+
+    if (b24->decoder)
+        arib_finalize_decoder(b24->decoder);
+
+    if (b24->lib_instance)
+        arib_instance_destroy(b24->lib_instance);
+
+    return 0;
+}
+
+#define RGB_TO_BGR(c) ((c & 0xff) << 16 | (c & 0xff00) | ((c >> 16) & 0xff))
+
+static void libaribb24_handle_regions(AVCodecContext *avctx, AVSubtitle *sub)
+{
+    Libaribb24Context *b24 = avctx->priv_data;
+    const arib_buf_region_t *region = arib_decoder_get_regions(b24->decoder);
+    unsigned int profile_font_size = get_profile_font_size(avctx->profile);
+    AVBPrint buf = { 0 };
+
+    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
+
+    while (region) {
+        ptrdiff_t region_length = region->p_end - region->p_start;
+        unsigned int ruby_region =
+            region->i_fontheight == (profile_font_size / 2);
+
+        // ASS requires us to make the colors BGR, so we convert here
+        int foreground_bgr_color = RGB_TO_BGR(region->i_foreground_color);
+        int background_bgr_color = RGB_TO_BGR(region->i_background_color);
+
+        if (region_length < 0) {
+            av_log(avctx, AV_LOG_ERROR, "Invalid negative region length!\n");
+            break;
+        }
+
+        if (region_length == 0 || (ruby_region && b24->aribb24_skip_ruby)) {
+            goto next_region;
+        }
+
+        // color and alpha
+        if (foreground_bgr_color != ASS_DEFAULT_COLOR)
+            av_bprintf(&buf, "{\\1c&H%06x&}", foreground_bgr_color);
+
+        if (region->i_foreground_alpha != 0)
+            av_bprintf(&buf, "{\\1a&H%02x&}", region->i_foreground_alpha);
+
+        if (background_bgr_color != ASS_DEFAULT_BACK_COLOR)
+            av_bprintf(&buf, "{\\3c&H%06x&}", background_bgr_color);
+
+        if (region->i_background_alpha != 0)
+            av_bprintf(&buf, "{\\3a&H%02x&}", region->i_background_alpha);
+
+        // font size
+        if (region->i_fontwidth  != profile_font_size ||
+            region->i_fontheight != profile_font_size) {
+            av_bprintf(&buf, "{\\fscx%d\\fscy%d}",
+                       (int)round(((double)region->i_fontwidth /
+                                   (double)profile_font_size) * 100),
+                       (int)round(((double)region->i_fontheight /
+                                   (double)profile_font_size) * 100));
+        }
+
+        // TODO: positioning
+
+        av_bprint_append_data(&buf, region->p_start, region_length);
+
+        av_bprintf(&buf, "{\\r}");
+
+next_region:
+        region = region->p_next;
+    }
+
+    av_log(avctx, AV_LOG_DEBUG, "Styled ASS line: %s\n",
+           buf.str);
+    ff_ass_add_rect(sub, buf.str, b24->read_order++,
+                    0, NULL, NULL);
+
+    av_bprint_finalize(&buf, NULL);
+}
+
+static int libaribb24_decode(AVCodecContext *avctx, void *data, int *got_sub_ptr, AVPacket *pkt)
+{
+    Libaribb24Context *b24 = avctx->priv_data;
+    AVSubtitle *sub = data;
+    size_t parsed_data_size = 0;
+    size_t decoded_subtitle_size = 0;
+    const unsigned char *parsed_data = NULL;
+    char *decoded_subtitle = NULL;
+    time_t subtitle_duration = 0;
+
+    if (pkt->size <= 0)
+        return pkt->size;
+
+    arib_parse_pes(b24->parser, pkt->data, pkt->size);
+
+    parsed_data = arib_parser_get_data(b24->parser,
+                                       &parsed_data_size);
+    if (!parsed_data || !parsed_data_size) {
+        av_log(avctx, AV_LOG_DEBUG, "No decode'able data was received from "
+                                    "packet (dts: %"PRId64", pts: %"PRId64").\n",
+               pkt->dts, pkt->pts);
+        return pkt->size;
+    }
+
+    decoded_subtitle_size = parsed_data_size * 4;
+    if (!(decoded_subtitle = av_mallocz(decoded_subtitle_size + 1))) {
+        av_log(avctx, AV_LOG_ERROR,
+               "Failed to allocate buffer for decoded subtitle!\n");
+        return AVERROR(ENOMEM);
+    }
+
+    decoded_subtitle_size = arib_decode_buffer(b24->decoder,
+                                               parsed_data,
+                                               parsed_data_size,
+                                               decoded_subtitle,
+                                               decoded_subtitle_size);
+
+    subtitle_duration = arib_decoder_get_time(b24->decoder);
+
+    if (avctx->pkt_timebase.num && pkt->pts != AV_NOPTS_VALUE)
+        sub->pts = av_rescale_q(pkt->pts,
+                                avctx->pkt_timebase, AV_TIME_BASE_Q);
+
+    sub->end_display_time = subtitle_duration ?
+                            av_rescale_q(subtitle_duration,
+                                         AV_TIME_BASE_Q,
+                                         (AVRational){1, 1000}) :
+                            UINT32_MAX;
+
+    av_log(avctx, AV_LOG_DEBUG,
+           "Result: '%s' (size: %zu, pkt_pts: %"PRId64", sub_pts: %"PRId64" "
+           "duration: %"PRIu32", pkt_timebase: %d/%d, time_base: %d/%d')\n",
+           decoded_subtitle ? decoded_subtitle : "<no subtitle>",
+           decoded_subtitle_size,
+           pkt->pts, sub->pts,
+           sub->end_display_time,
+           avctx->pkt_timebase.num, avctx->pkt_timebase.den,
+           avctx->time_base.num, avctx->time_base.den);
+
+    if (decoded_subtitle)
+        libaribb24_handle_regions(avctx, sub);
+
+    *got_sub_ptr = sub->num_rects > 0;
+
+    av_free(decoded_subtitle);
+
+    // flush the region buffers, otherwise the linked list keeps getting
+    // longer and longer...
+    arib_finalize_decoder(b24->decoder);
+
+    return pkt->size;
+}
+
+static void libaribb24_flush(AVCodecContext *avctx)
+{
+    Libaribb24Context *b24 = avctx->priv_data;
+    if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
+        b24->read_order = 0;
+}
+
+#define OFFSET(x) offsetof(Libaribb24Context, x)
+#define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
+static const AVOption options[] = {
+    { "aribb24-base-path", "set the base path for the libaribb24 library",
+      OFFSET(aribb24_base_path), AV_OPT_TYPE_STRING, { 0 }, 0, 0, SD },
+    { "aribb24-skip-ruby-text", "skip ruby text blocks during decoding",
+      OFFSET(aribb24_skip_ruby), AV_OPT_TYPE_BOOL, { 1 }, 0, 1, SD },
+    { NULL }
+};
+
+static const AVClass aribb24_class = {
+    .class_name = "libaribb24 decoder",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVCodec ff_libaribb24_decoder = {
+    .name      = "libaribb24",
+    .long_name = NULL_IF_CONFIG_SMALL("libaribb24 ARIB STD-B24 caption decoder"),
+    .type      = AVMEDIA_TYPE_SUBTITLE,
+    .id        = AV_CODEC_ID_ARIB_CAPTION,
+    .priv_data_size = sizeof(Libaribb24Context),
+    .init      = libaribb24_init,
+    .close     = libaribb24_close,
+    .decode    = libaribb24_decode,
+    .flush     = libaribb24_flush,
+    .priv_class= &aribb24_class,
+    .wrapper_name = "libaribb24",
+};