PeerStreamer

/*

 * 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 "libavcore/imgutils.h"

//#define DEBUG_PACKET_CONTENTS

#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 PGSSubPresentation {

    int x;

    int y;

    int id_number;

    int object_number;

} 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 {

    PGSSubPresentation presentation;

    uint32_t           clut[256];

    PGSSubPicture      picture;

} PGSSubContext;

static av_cold int init_decoder(AVCodecContext *avctx)

{

    avctx->pix_fmt = PIX_FMT_PAL8;

    return 0;

}

static av_cold int close_decoder(AVCodecContext *avctx)

{

    PGSSubContext *ctx = avctx->priv_data;

    av_freep(&ctx->picture.rle);

    ctx->picture.rle_buffer_size  = 0;

    return 0;

}

/**

 * Decode the RLE data.

 *

 * The subtitle is stored as an 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,

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

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

        return -1;

    pixel_count = 0;

    line_count  = 0;

    while (buf < rle_bitmap_end && line_count < sub->rects[0]->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[0]->w * sub->rects[0]->h) {

            memset(sub->rects[0]->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[0]->w > 0)

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

                       pixel_count % sub->rects[0]->w, sub->rects[0]->w);

            line_count++;

        }

    }

    if (pixel_count < sub->rects[0]->w * sub->rects[0]->h) {

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

        return -1;

    }

    dprintf(avctx, "Pixel Count = %d, Area = %d\n", pixel_count, sub->rects[0]->w * sub->rects[0]->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;

    if (buf_size <= 4)

        return -1;

    buf_size -= 4;

    /* skip 3 unknown bytes: Object ID (2 bytes), Version Number */

    buf += 3;

    /* 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->picture.rle_remaining_len)

            return -1;

        memcpy(ctx->picture.rle + ctx->picture.rle_data_len, buf, buf_size);

        ctx->picture.rle_data_len += buf_size;

        ctx->picture.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 then video.\n");

        return -1;

    }

    ctx->picture.w = width;

    ctx->picture.h = height;

    av_fast_malloc(&ctx->picture.rle, &ctx->picture.rle_buffer_size, rle_bitmap_len);

    if (!ctx->picture.rle)

        return -1;

    memcpy(ctx->picture.rle, buf, buf_size);

    ctx->picture.rle_data_len = buf_size;

    ctx->picture.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);

        cb        = bytestream_get_byte(&buf);

        cr        = bytestream_get_byte(&buf);

        alpha     = bytestream_get_byte(&buf);

        YUV_TO_RGB1(cb, cr);

        YUV_TO_RGB2(r, g, b, y);

        dprintf(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

 * @todo TODO: Implement forcing of subtitles

 */

static void parse_presentation_segment(AVCodecContext *avctx,

                                       const uint8_t *buf, int buf_size)

{

    PGSSubContext *ctx = avctx->priv_data;

    int x, y;

    int w = bytestream_get_be16(&buf);

    int h = bytestream_get_be16(&buf);

    dprintf(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_number = bytestream_get_byte(&buf);

    if (!ctx->presentation.object_number)

        return;

    /*

     * Skip 4 bytes of unknown:

     *     object_id_ref (2 bytes),

     *     window_id_ref,

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

     */

    buf += 4;

    x = bytestream_get_be16(&buf);

    y = bytestream_get_be16(&buf);

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

    dprintf(avctx, "Subtitle Placement x=%d, y=%d\n", x, y);

    if (x > avctx->width || 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",

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

        x = 0; y = 0;

    }

    /* Fill in dimensions */

    ctx->presentation.x = x;

    ctx->presentation.y = y;

}

/**

 * 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;

    /*

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

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

     *      not been cleared by a subsequent empty display command.

     */

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

    // Blank if last object_number was 0.

    // Note that this may be wrong for more complex subtitles.

    if (!ctx->presentation.object_number)

        return 1;

    sub->start_display_time = 0;

    sub->end_display_time   = 20000;

    sub->format             = 0;

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

    sub->rects[0]  = av_mallocz(sizeof(*sub->rects[0]));

    sub->num_rects = 1;

    sub->rects[0]->x    = ctx->presentation.x;

    sub->rects[0]->y    = ctx->presentation.y;

    sub->rects[0]->w    = ctx->picture.w;

    sub->rects[0]->h    = ctx->picture.h;

    sub->rects[0]->type = SUBTITLE_BITMAP;

    /* Process bitmap */

    sub->rects[0]->pict.linesize[0] = ctx->picture.w;

    if (ctx->picture.rle) {

        if (ctx->picture.rle_remaining_len)

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

                   ctx->picture.rle_data_len, ctx->picture.rle_remaining_len);

        if(decode_rle(avctx, sub, ctx->picture.rle, ctx->picture.rle_data_len) < 0)

            return 0;

    }

    /* Allocate memory for colors */

    sub->rects[0]->nb_colors    = 256;

    sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);

    memcpy(sub->rects[0]->pict.data[1], ctx->clut, sub->rects[0]->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;

    const uint8_t *buf_end;

    uint8_t       segment_type;

    int           segment_length;

#ifdef DEBUG_PACKET_CONTENTS

    int i;

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

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

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

        if (i % 16 == 15)

            av_log(avctx, AV_LOG_INFO, "\n");

    }

    if (i & 15)

        av_log(avctx, AV_LOG_INFO, "\n");

#endif

    *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);

        dprintf(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);

            break;

        case WINDOW_SEGMENT:

            /*

             * Window Segment Structure (No new information provided):

             *     2 bytes: Unkown,

             *     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;

}

AVCodec ff_pgssub_decoder = {

    "pgssub",

    AVMEDIA_TYPE_SUBTITLE,

    CODEC_ID_HDMV_PGS_SUBTITLE,

    sizeof(PGSSubContext),

    init_decoder,

    NULL,

    close_decoder,

    decode,

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

};