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ffmpeg/libavcodec/pgssubdec.c

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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"
#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;
}
av_dlog(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 than 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);
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
* @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);
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_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).*/
av_dlog(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.
*/
// 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;
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);
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 = {
.name = "pgssub",
.type = AVMEDIA_TYPE_SUBTITLE,
.id = CODEC_ID_HDMV_PGS_SUBTITLE,
.priv_data_size = sizeof(PGSSubContext),
.init = init_decoder,
.close = close_decoder,
.decode = decode,
.long_name = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),
};
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