mirror of
https://git.ffmpeg.org/ffmpeg.git
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87 lines
2.4 KiB
C
87 lines
2.4 KiB
C
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#include "avcodec.h"
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#include "bitstream.h"
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#include "bytestream.h"
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static int decode_init(AVCodecContext *avctx) {
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avctx->pix_fmt = PIX_FMT_PAL8;
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return 0;
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}
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static const uint8_t runbits[8] = { 2, 2, 6, 6, 10, 10, 14, 14 };
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static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
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uint8_t *buf, int buf_size) {
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AVSubtitle *sub = data;
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uint8_t *buf_end = buf + buf_size;
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uint8_t *bitmap;
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int w, h, x, y, rlelen, i;
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GetBitContext gb;
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// check that at least header fits
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if (buf_size < 27 + 7 * 2 + 4 * 3) {
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av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
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return -1;
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}
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// read header
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w = bytestream_get_le16(&buf);
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h = bytestream_get_le16(&buf);
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if (avcodec_check_dimensions(avctx, w, h) < 0)
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return -1;
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x = bytestream_get_le16(&buf);
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y = bytestream_get_le16(&buf);
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// skip bottom right position, it gives no new information
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bytestream_get_le16(&buf);
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bytestream_get_le16(&buf);
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rlelen = bytestream_get_le16(&buf);
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// allocate sub and set values
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if (!sub->rects) {
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sub->rects = av_mallocz(sizeof(AVSubtitleRect));
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sub->num_rects = 1;
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}
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av_freep(sub->rects[0].bitmap);
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sub->rects[0].x = x; sub->rects[0].y = y;
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sub->rects[0].w = w; sub->rects[0].h = h;
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sub->rects[0].linesize = w;
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sub->rects[0].bitmap = av_malloc(w * h);
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sub->rects[0].nb_colors = 4;
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sub->rects[0].rgba_palette = av_malloc(sub->rects[0].nb_colors * 4);
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// read palette
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for (i = 0; i < sub->rects[0].nb_colors; i++)
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sub->rects[0].rgba_palette[i] = bytestream_get_be24(&buf);
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// process RLE-compressed data
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rlelen = FFMIN(rlelen, buf_end - buf);
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init_get_bits(&gb, buf, rlelen * 8);
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bitmap = sub->rects[0].bitmap;
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for (y = 0; y < h; y++) {
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for (x = 0; x < w; ) {
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int log2 = ff_log2_tab[show_bits(&gb, 8)];
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int run = get_bits(&gb, runbits[log2]);
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int colour = get_bits(&gb, 2);
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run = FFMIN(run, w - x);
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// run length 0 means till end of row
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if (!run) run = w - x;
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memset(bitmap, colour, run);
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bitmap += run;
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x += run;
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}
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align_get_bits(&gb);
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}
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*data_size = 1;
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return buf_size;
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}
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AVCodec xsub_decoder = {
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"xsub",
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CODEC_TYPE_SUBTITLE,
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CODEC_ID_XSUB,
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0,
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decode_init,
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NULL,
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NULL,
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decode_frame,
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};
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