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/*

 * PGS subtitle decoder

 * Copyright (c) 2009 Stephen Backway

 *

 * 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

 */

/**

 * @file

 * PGS subtitle decoder

 */

#include "avcodec.h"

#include "dsputil.h"

#include "bytestream.h"

#include "libavutil/colorspace.h"

#include "libavutil/imgutils.h"

#include "libavutil/opt.h"

#define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))

enum SegmentType {

    PALETTE_SEGMENT      = 0x14,

    PICTURE_SEGMENT      = 0x15,

    PRESENTATION_SEGMENT = 0x16,

    WINDOW_SEGMENT       = 0x17,

    DISPLAY_SEGMENT      = 0x80,

};

typedef struct PGSSubPictureReference {

    int x;

    int y;

    int picture_id;

    int composition;

} PGSSubPictureReference;

typedef struct PGSSubPresentation {

    int                    id_number;

    int                    object_count;

    PGSSubPictureReference *objects;

    int64_t pts;

} PGSSubPresentation;

typedef struct PGSSubPicture {

    int          w;

    int          h;

    uint8_t      *rle;

    unsigned int rle_buffer_size, rle_data_len;

    unsigned int rle_remaining_len;

} PGSSubPicture;

typedef struct PGSSubContext {

    AVClass *class;

    PGSSubPresentation presentation;

    uint32_t           clut[256];

    PGSSubPicture      pictures[UINT16_MAX];

    int forced_subs_only;

} PGSSubContext;

static av_cold int init_decoder(AVCodecContext *avctx)

{

    avctx->pix_fmt     = AV_PIX_FMT_PAL8;

    return 0;

}

static av_cold int close_decoder(AVCodecContext *avctx)

{

    uint16_t picture;

    PGSSubContext *ctx = avctx->priv_data;

    av_freep(&ctx->presentation.objects);

    ctx->presentation.object_count = 0;

    for (picture = 0; picture < UINT16_MAX; ++picture) {

        av_freep(&ctx->pictures[picture].rle);

        ctx->pictures[picture].rle_buffer_size = 0;

    }

    return 0;

}

/**

 * Decode the RLE data.

 *

 * The subtitle is stored as a Run Length Encoded image.

 *

 * @param avctx contains the current codec context

 * @param sub pointer to the processed subtitle data

 * @param buf pointer to the RLE data to process

 * @param buf_size size of the RLE data to process

 */

static int decode_rle(AVCodecContext *avctx, AVSubtitle *sub, int rect,

                      const uint8_t *buf, unsigned int buf_size)

{

    const uint8_t *rle_bitmap_end;

    int pixel_count, line_count;

    rle_bitmap_end = buf + buf_size;

    sub->rects[rect]->pict.data[0] = av_malloc(sub->rects[rect]->w * sub->rects[rect]->h);

    if (!sub->rects[rect]->pict.data[0])

        return -1;

    pixel_count = 0;

    line_count  = 0;

    while (buf < rle_bitmap_end && line_count < sub->rects[rect]->h) {

        uint8_t flags, color;

        int run;

        color = bytestream_get_byte(&buf);

        run   = 1;

        if (color == 0x00) {

            flags = bytestream_get_byte(&buf);

            run   = flags & 0x3f;

            if (flags & 0x40)

                run = (run << 8) + bytestream_get_byte(&buf);

            color = flags & 0x80 ? bytestream_get_byte(&buf) : 0;

        }

        if (run > 0 && pixel_count + run <= sub->rects[rect]->w * sub->rects[rect]->h) {

            memset(sub->rects[rect]->pict.data[0] + pixel_count, color, run);

            pixel_count += run;

        } else if (!run) {

            /*

             * New Line. Check if correct pixels decoded, if not display warning

             * and adjust bitmap pointer to correct new line position.

             */

            if (pixel_count % sub->rects[rect]->w > 0)

                av_log(avctx, AV_LOG_ERROR, "Decoded %d pixels, when line should be %d pixels\n",

                       pixel_count % sub->rects[rect]->w, sub->rects[rect]->w);

            line_count++;

        }

    }

    if (pixel_count < sub->rects[rect]->w * sub->rects[rect]->h) {

        av_log(avctx, AV_LOG_ERROR, "Insufficient RLE data for subtitle\n");

        return -1;

    }

    av_dlog(avctx, "Pixel Count = %d, Area = %d\n", pixel_count, sub->rects[rect]->w * sub->rects[rect]->h);

    return 0;

}

/**

 * Parse the picture segment packet.

 *

 * The picture segment contains details on the sequence id,

 * width, height and Run Length Encoded (RLE) bitmap data.

 *

 * @param avctx contains the current codec context

 * @param buf pointer to the packet to process

 * @param buf_size size of packet to process

 * @todo TODO: Enable support for RLE data over multiple packets

 */

static int parse_picture_segment(AVCodecContext *avctx,

                                  const uint8_t *buf, int buf_size)

{

    PGSSubContext *ctx = avctx->priv_data;

    uint8_t sequence_desc;

    unsigned int rle_bitmap_len, width, height;

    uint16_t picture_id;

    if (buf_size <= 4)

        return -1;

    buf_size -= 4;

    picture_id = bytestream_get_be16(&buf);

    /* skip 1 unknown byte: Version Number */

    buf++;

    /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */

    sequence_desc = bytestream_get_byte(&buf);

    if (!(sequence_desc & 0x80)) {

        /* Additional RLE data */

        if (buf_size > ctx->pictures[picture_id].rle_remaining_len)

            return -1;

        memcpy(ctx->pictures[picture_id].rle + ctx->pictures[picture_id].rle_data_len, buf, buf_size);

        ctx->pictures[picture_id].rle_data_len += buf_size;

        ctx->pictures[picture_id].rle_remaining_len -= buf_size;

        return 0;

    }

    if (buf_size <= 7)

        return -1;

    buf_size -= 7;

    /* Decode rle bitmap length, stored size includes width/height data */

    rle_bitmap_len = bytestream_get_be24(&buf) - 2*2;

    /* Get bitmap dimensions from data */

    width  = bytestream_get_be16(&buf);

    height = bytestream_get_be16(&buf);

    /* Make sure the bitmap is not too large */

    if (avctx->width < width || avctx->height < height) {

        av_log(avctx, AV_LOG_ERROR, "Bitmap dimensions larger than video.\n");

        return -1;

    }

    if (buf_size > rle_bitmap_len) {

        av_log(avctx, AV_LOG_ERROR, "too much RLE data\n");

        return AVERROR_INVALIDDATA;

    }

    ctx->pictures[picture_id].w = width;

    ctx->pictures[picture_id].h = height;

    av_fast_malloc(&ctx->pictures[picture_id].rle, &ctx->pictures[picture_id].rle_buffer_size, rle_bitmap_len);

    if (!ctx->pictures[picture_id].rle)

        return -1;

    memcpy(ctx->pictures[picture_id].rle, buf, buf_size);

    ctx->pictures[picture_id].rle_data_len      = buf_size;

    ctx->pictures[picture_id].rle_remaining_len = rle_bitmap_len - buf_size;

    return 0;

}

/**

 * Parse the palette segment packet.

 *

 * The palette segment contains details of the palette,

 * a maximum of 256 colors can be defined.

 *

 * @param avctx contains the current codec context

 * @param buf pointer to the packet to process

 * @param buf_size size of packet to process

 */

static void parse_palette_segment(AVCodecContext *avctx,

                                  const uint8_t *buf, int buf_size)

{

    PGSSubContext *ctx = avctx->priv_data;

    const uint8_t *buf_end = buf + buf_size;

    const uint8_t *cm      = ff_cropTbl + MAX_NEG_CROP;

    int color_id;

    int y, cb, cr, alpha;

    int r, g, b, r_add, g_add, b_add;

    /* Skip two null bytes */

    buf += 2;

    while (buf < buf_end) {

        color_id  = bytestream_get_byte(&buf);

        y         = bytestream_get_byte(&buf);

        cr        = bytestream_get_byte(&buf);

        cb        = bytestream_get_byte(&buf);

        alpha     = bytestream_get_byte(&buf);

        YUV_TO_RGB1(cb, cr);

        YUV_TO_RGB2(r, g, b, y);

        av_dlog(avctx, "Color %d := (%d,%d,%d,%d)\n", color_id, r, g, b, alpha);

        /* Store color in palette */

        ctx->clut[color_id] = RGBA(r,g,b,alpha);

    }

}

/**

 * Parse the presentation segment packet.

 *

 * The presentation segment contains details on the video

 * width, video height, x & y subtitle position.

 *

 * @param avctx contains the current codec context

 * @param buf pointer to the packet to process

 * @param buf_size size of packet to process

 * @todo TODO: Implement cropping

 */

static void parse_presentation_segment(AVCodecContext *avctx,

                                       const uint8_t *buf, int buf_size,

                                       int64_t pts)

{

    PGSSubContext *ctx = avctx->priv_data;

    int w = bytestream_get_be16(&buf);

    int h = bytestream_get_be16(&buf);

    uint16_t object_index;

    ctx->presentation.pts = pts;

    av_dlog(avctx, "Video Dimensions %dx%d\n",

            w, h);

    if (av_image_check_size(w, h, 0, avctx) >= 0)

        avcodec_set_dimensions(avctx, w, h);

    /* Skip 1 bytes of unknown, frame rate? */

    buf++;

    ctx->presentation.id_number = bytestream_get_be16(&buf);

    /*

     * Skip 3 bytes of unknown:

     *     state

     *     palette_update_flag (0x80),

     *     palette_id_to_use,

     */

    buf += 3;

    ctx->presentation.object_count = bytestream_get_byte(&buf);

    if (!ctx->presentation.object_count)

        return;

    /* Verify that enough bytes are remaining for all of the objects. */

    buf_size -= 11;

    if (buf_size < ctx->presentation.object_count * 8) {

        ctx->presentation.object_count = 0;

        return;

    }

    av_freep(&ctx->presentation.objects);

    ctx->presentation.objects = av_malloc(sizeof(PGSSubPictureReference) * ctx->presentation.object_count);

    if (!ctx->presentation.objects) {

        ctx->presentation.object_count = 0;

        return;

    }

    for (object_index = 0; object_index < ctx->presentation.object_count; ++object_index) {

        PGSSubPictureReference *reference = &ctx->presentation.objects[object_index];

        reference->picture_id             = bytestream_get_be16(&buf);

        /* Skip window_id_ref */

        buf++;

        /* composition_flag (0x80 - object cropped, 0x40 - object forced) */

        reference->composition = bytestream_get_byte(&buf);

        reference->x = bytestream_get_be16(&buf);

        reference->y = bytestream_get_be16(&buf);

        /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/

        av_dlog(avctx, "Subtitle Placement ID=%d, x=%d, y=%d\n", reference->picture_id, reference->x, reference->y);

        if (reference->x > avctx->width || reference->y > avctx->height) {

            av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",

                   reference->x, reference->y, avctx->width, avctx->height);

            reference->x = 0;

            reference->y = 0;

        }

    }

}

/**

 * Parse the display segment packet.

 *

 * The display segment controls the updating of the display.

 *

 * @param avctx contains the current codec context

 * @param data pointer to the data pertaining the subtitle to display

 * @param buf pointer to the packet to process

 * @param buf_size size of packet to process

 * @todo TODO: Fix start time, relies on correct PTS, currently too late

 *

 * @todo TODO: Fix end time, normally cleared by a second display

 * @todo       segment, which is currently ignored as it clears

 * @todo       the subtitle too early.

 */

static int display_end_segment(AVCodecContext *avctx, void *data,

                               const uint8_t *buf, int buf_size)

{

    AVSubtitle    *sub = data;

    PGSSubContext *ctx = avctx->priv_data;

    int64_t pts;

    uint16_t rect;

    /*

     *      The end display time is a timeout value and is only reached

     *      if the next subtitle is later than timeout or subtitle has

     *      not been cleared by a subsequent empty display command.

     */

    pts = ctx->presentation.pts != AV_NOPTS_VALUE ? ctx->presentation.pts : sub->pts;

    memset(sub, 0, sizeof(*sub));

    sub->pts = pts;

    ctx->presentation.pts = AV_NOPTS_VALUE;

    // Blank if last object_count was 0.

    if (!ctx->presentation.object_count)

        return 1;

    sub->start_display_time = 0;

    sub->end_display_time   = 20000;

    sub->format             = 0;

    sub->num_rects = ctx->presentation.object_count;

    sub->rects     = av_mallocz(sizeof(*sub->rects) * sub->num_rects);

    for (rect = 0; rect < sub->num_rects; ++rect) {

        uint16_t picture_id    = ctx->presentation.objects[rect].picture_id;

        sub->rects[rect]       = av_mallocz(sizeof(*sub->rects[rect]));

        sub->rects[rect]->x    = ctx->presentation.objects[rect].x;

        sub->rects[rect]->y    = ctx->presentation.objects[rect].y;

        sub->rects[rect]->w    = ctx->pictures[picture_id].w;

        sub->rects[rect]->h    = ctx->pictures[picture_id].h;

        sub->rects[rect]->type = SUBTITLE_BITMAP;

        /* Process bitmap */

        sub->rects[rect]->pict.linesize[0] = ctx->pictures[picture_id].w;

        if (ctx->pictures[picture_id].rle) {

            if (ctx->pictures[picture_id].rle_remaining_len)

                av_log(avctx, AV_LOG_ERROR, "RLE data length %u is %u bytes shorter than expected\n",

                       ctx->pictures[picture_id].rle_data_len, ctx->pictures[picture_id].rle_remaining_len);

            if (decode_rle(avctx, sub, rect, ctx->pictures[picture_id].rle, ctx->pictures[picture_id].rle_data_len) < 0)

                return 0;

        }

        /* Allocate memory for colors */

        sub->rects[rect]->nb_colors    = 256;

        sub->rects[rect]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);

        /* Copy the forced flag */

        sub->rects[rect]->flags = (ctx->presentation.objects[rect].composition & 0x40) != 0 ? AV_SUBTITLE_FLAG_FORCED : 0;

        if (!ctx->forced_subs_only || ctx->presentation.objects[rect].composition & 0x40)

        memcpy(sub->rects[rect]->pict.data[1], ctx->clut, sub->rects[rect]->nb_colors * sizeof(uint32_t));

    }

    return 1;

}

static int decode(AVCodecContext *avctx, void *data, int *data_size,

                  AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size       = avpkt->size;

    AVSubtitle *sub    = data;

    const uint8_t *buf_end;

    uint8_t       segment_type;

    int           segment_length;

    int i;

    av_dlog(avctx, "PGS sub packet:\n");

    for (i = 0; i < buf_size; i++) {

        av_dlog(avctx, "%02x ", buf[i]);

        if (i % 16 == 15)

            av_dlog(avctx, "\n");

    }

    if (i & 15)

        av_dlog(avctx, "\n");

    *data_size = 0;

    /* Ensure that we have received at a least a segment code and segment length */

    if (buf_size < 3)

        return -1;

    buf_end = buf + buf_size;

    /* Step through buffer to identify segments */

    while (buf < buf_end) {

        segment_type   = bytestream_get_byte(&buf);

        segment_length = bytestream_get_be16(&buf);

        av_dlog(avctx, "Segment Length %d, Segment Type %x\n", segment_length, segment_type);

        if (segment_type != DISPLAY_SEGMENT && segment_length > buf_end - buf)

            break;

        switch (segment_type) {

        case PALETTE_SEGMENT:

            parse_palette_segment(avctx, buf, segment_length);

            break;

        case PICTURE_SEGMENT:

            parse_picture_segment(avctx, buf, segment_length);

            break;

        case PRESENTATION_SEGMENT:

            parse_presentation_segment(avctx, buf, segment_length, sub->pts);

            break;

        case WINDOW_SEGMENT:

            /*

             * Window Segment Structure (No new information provided):

             *     2 bytes: Unknown,

             *     2 bytes: X position of subtitle,

             *     2 bytes: Y position of subtitle,

             *     2 bytes: Width of subtitle,

             *     2 bytes: Height of subtitle.

             */

            break;

        case DISPLAY_SEGMENT:

            *data_size = display_end_segment(avctx, data, buf, segment_length);

            break;

        default:

            av_log(avctx, AV_LOG_ERROR, "Unknown subtitle segment type 0x%x, length %d\n",

                   segment_type, segment_length);

            break;

        }

        buf += segment_length;

    }

    return buf_size;

}

#define OFFSET(x) offsetof(PGSSubContext, x)

#define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM

static const AVOption options[] = {

    {"forced_subs_only", "Only show forced subtitles", OFFSET(forced_subs_only), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, SD},

    { NULL },

};

static const AVClass pgsdec_class = {

    .class_name = "PGS subtitle decoder",

    .item_name  = av_default_item_name,

    .option     = options,

    .version    = LIBAVUTIL_VERSION_INT,

};

AVCodec ff_pgssub_decoder = {

    .name           = "pgssub",

    .long_name      = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),

    .type           = AVMEDIA_TYPE_SUBTITLE,

    .id             = AV_CODEC_ID_HDMV_PGS_SUBTITLE,

    .priv_data_size = sizeof(PGSSubContext),

    .init           = init_decoder,

    .close          = close_decoder,

    .decode         = decode,

    .priv_class     = &pgsdec_class,

};