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#include "avcodec.h"
#include "bitstream.h"
#include "bytestream.h"
static int decode_init(AVCodecContext *avctx) {
avctx->pix_fmt = PIX_FMT_PAL8;
return 0;
}
static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 6, 10, 10, 1 };
static uint64_t parse_timecode(AVCodecContext *avctx, uint8_t *buf) {
int i;
int64_t ms = 0;
if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
return AV_NOPTS_VALUE;
for (i = 0; i < sizeof(tc_offsets); i++) {
uint8_t c = buf[tc_offsets[i]] - '0';
if (c > 9) return AV_NOPTS_VALUE;
ms = (ms + c) * tc_muls[i];
}
ms = av_rescale_q(ms, (AVRational){1, 1000}, avctx->time_base);
return ms;
}
static const uint8_t runbits[8] = { 2, 2, 6, 6, 10, 10, 14, 14 };
static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
uint8_t *buf, int buf_size) {
AVSubtitle *sub = data;
uint8_t *buf_end = buf + buf_size;
uint8_t *bitmap;
int w, h, x, y, rlelen, i;
GetBitContext gb;
// check that at least header fits
if (buf_size < 27 + 7 * 2 + 4 * 3) {
av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
return -1;
}
// read start and end time
if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
return -1;
}
sub->start_display_time = parse_timecode(avctx, buf + 1);
sub->end_display_time = parse_timecode(avctx, buf + 14);
buf += 27;
// read header
w = bytestream_get_le16(&buf);
h = bytestream_get_le16(&buf);
if (avcodec_check_dimensions(avctx, w, h) < 0)
return -1;
x = bytestream_get_le16(&buf);
y = bytestream_get_le16(&buf);
// skip bottom right position, it gives no new information
bytestream_get_le16(&buf);
bytestream_get_le16(&buf);
rlelen = bytestream_get_le16(&buf);
// allocate sub and set values
if (!sub->rects) {
sub->rects = av_mallocz(sizeof(AVSubtitleRect));
sub->num_rects = 1;
}
av_freep(sub->rects[0].bitmap);
sub->rects[0].x = x; sub->rects[0].y = y;
sub->rects[0].w = w; sub->rects[0].h = h;
sub->rects[0].linesize = w;
sub->rects[0].bitmap = av_malloc(w * h);
sub->rects[0].nb_colors = 4;
sub->rects[0].rgba_palette = av_malloc(sub->rects[0].nb_colors * 4);
// read palette
for (i = 0; i < sub->rects[0].nb_colors; i++)
sub->rects[0].rgba_palette[i] = bytestream_get_be24(&buf);
// process RLE-compressed data
rlelen = FFMIN(rlelen, buf_end - buf);
init_get_bits(&gb, buf, rlelen * 8);
bitmap = sub->rects[0].bitmap;
for (y = 0; y < h; y++) {
for (x = 0; x < w; ) {
int log2 = ff_log2_tab[show_bits(&gb, 8)];
int run = get_bits(&gb, runbits[log2]);
int colour = get_bits(&gb, 2);
run = FFMIN(run, w - x);
// run length 0 means till end of row
if (!run) run = w - x;
memset(bitmap, colour, run);
bitmap += run;
x += run;
}
align_get_bits(&gb);
}
*data_size = 1;
return buf_size;
}
AVCodec xsub_decoder = {
"xsub",
CODEC_TYPE_SUBTITLE,
CODEC_ID_XSUB,
0,
decode_init,
NULL,
NULL,
decode_frame,
};
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