dvbsub encoder, patch by Wolfram Gloger < wmglo AH dent POIS med POIS uni-muenchen POIS de >

Original thread:
Date: 8 Oct 2005 09:35:38 -0000
Subject: [Ffmpeg-devel] [PATCH] dvdsub encoder -- 2nd version

Originally committed as revision 4706 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 248 insertions, 0 deletions

diff --git a/libavcodec/dvdsubenc.c b/libavcodec/dvdsubenc.c
new file mode 100644
index 0000000000..632586c6d0
--- /dev/null
+++ b/libavcodec/dvdsubenc.c
@@ -0,0 +1,248 @@
+/*
+ * DVD subtitle encoding for ffmpeg
+ * Copyright (c) 2005 Wolfram Gloger.
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include "avcodec.h"
+
+#undef NDEBUG
+#include <assert.h>
+
+typedef struct DVDSubtitleContext {
+} DVDSubtitleContext;
+
+// ncnt is the nibble counter
+#define PUTNIBBLE(val)\
+do {\
+    if (ncnt++ & 1)\
+        *q++ = bitbuf | ((val) & 0x0f);\
+    else\
+        bitbuf = (val) << 4;\
+} while(0)
+
+static void dvd_encode_rle(uint8_t **pq,
+                           const uint8_t *bitmap, int linesize,
+                           int w, int h,
+                           const int cmap[256])
+{
+    uint8_t *q;
+    unsigned int bitbuf = 0;
+    int ncnt;
+    int x, y, len, color;
+
+    q = *pq;
+
+    for (y = 0; y < h; ++y) {
+        ncnt = 0;
+        for(x = 0; x < w; x += len) {
+            color = bitmap[x];
+            for (len=1; x+len < w; ++len)
+                if (bitmap[x+len] != color)
+                    break;
+            color = cmap[color];
+            assert(color < 4);
+            if (len < 0x04) {
+                PUTNIBBLE((len << 2)|color);
+            } else if (len < 0x10) {
+                PUTNIBBLE(len >> 2);
+                PUTNIBBLE((len << 2)|color);
+            } else if (len < 0x40) {
+                PUTNIBBLE(0);
+                PUTNIBBLE(len >> 2);
+                PUTNIBBLE((len << 2)|color);
+            } else if (x+len == w) {
+                PUTNIBBLE(0);
+                PUTNIBBLE(0);
+                PUTNIBBLE(0);
+                PUTNIBBLE(color);
+            } else {
+                if (len > 0xff)
+                    len = 0xff;
+                PUTNIBBLE(0);
+                PUTNIBBLE(len >> 6);
+                PUTNIBBLE(len >> 2);
+                PUTNIBBLE((len << 2)|color);
+            }
+        }
+        /* end of line */
+        if (ncnt & 1)
+            PUTNIBBLE(0);
+        bitmap += linesize;
+    }
+
+    *pq = q;
+}
+
+static inline void putbe16(uint8_t **pq, uint16_t v)
+{
+    uint8_t *q = *pq;
+    *q++ = v >> 8;
+    *q++ = v;
+    *pq = q;
+}
+
+static int encode_dvd_subtitles(uint8_t *outbuf, int outbuf_size,
+                                const AVSubtitle *h)
+{
+    uint8_t *q, *qq;
+    int object_id;
+    int offset1[20], offset2[20];
+    int i, imax, color, alpha, rects = h->num_rects;
+    unsigned long hmax;
+    unsigned long hist[256];
+    int           cmap[256];
+
+    if (rects == 0 || h->rects == NULL)
+        return -1;
+    if (rects > 20)
+        rects = 20;
+
+    // analyze bitmaps, compress to 4 colors
+    for (i=0; i<256; ++i) {
+        hist[i] = 0;
+        cmap[i] = 0;
+    }
+    for (object_id = 0; object_id < rects; object_id++)
+        for (i=0; i<h->rects[object_id].w*h->rects[object_id].h; ++i) {
+            color = h->rects[object_id].bitmap[i];
+            // only count non-transparent pixels
+            alpha = h->rects[object_id].rgba_palette[color] >> 24;
+            hist[color] += alpha;
+        }
+    for (color=3;; --color) {
+        hmax = 0;
+        imax = 0;
+        for (i=0; i<256; ++i)
+            if (hist[i] > hmax) {
+                imax = i;
+                hmax = hist[i];
+            }
+        if (hmax == 0)
+            break;
+        if (color == 0)
+            color = 3;
+        av_log(NULL, AV_LOG_DEBUG, "dvd_subtitle hist[%d]=%ld -> col %d\n",
+               imax, hist[imax], color);
+        cmap[imax] = color;
+        hist[imax] = 0;
+    }
+
+
+    // encode data block
+    q = outbuf + 4;
+    for (object_id = 0; object_id < rects; object_id++) {
+        offset1[object_id] = q - outbuf;
+        // worst case memory requirement: 1 nibble per pixel..
+        if ((q - outbuf) + h->rects[object_id].w*h->rects[object_id].h/2
+            + 17*rects + 21 > outbuf_size) {
+            av_log(NULL, AV_LOG_ERROR, "dvd_subtitle too big\n");
+            return -1;
+        }
+        dvd_encode_rle(&q, h->rects[object_id].bitmap,
+                       h->rects[object_id].w*2,
+                       h->rects[object_id].w, h->rects[object_id].h >> 1,
+                       cmap);
+        offset2[object_id] = q - outbuf;
+        dvd_encode_rle(&q, h->rects[object_id].bitmap + h->rects[object_id].w,
+                       h->rects[object_id].w*2,
+                       h->rects[object_id].w, h->rects[object_id].h >> 1,
+                       cmap);
+    }
+
+    // set data packet size
+    qq = outbuf + 2;
+    putbe16(&qq, q - outbuf);
+
+    // send start display command
+    putbe16(&q, (h->start_display_time*90) >> 10);
+    putbe16(&q, (q - outbuf) /*- 2 */ + 8 + 12*rects + 2);
+    *q++ = 0x03; // palette - 4 nibbles
+    *q++ = 0x03; *q++ = 0x7f;
+    *q++ = 0x04; // alpha - 4 nibbles
+    *q++ = 0xf0; *q++ = 0x00;
+    //*q++ = 0x0f; *q++ = 0xff;
+
+    // XXX not sure if more than one rect can really be encoded..
+    // 12 bytes per rect
+    for (object_id = 0; object_id < rects; object_id++) {
+        int x2 = h->rects[object_id].x + h->rects[object_id].w - 1;
+        int y2 = h->rects[object_id].y + h->rects[object_id].h - 1;
+
+        *q++ = 0x05;
+        // x1 x2 -> 6 nibbles
+        *q++ = h->rects[object_id].x >> 4;
+        *q++ = (h->rects[object_id].x << 4) | ((x2 >> 8) & 0xf);
+        *q++ = x2;
+        // y1 y2 -> 6 nibbles
+        *q++ = h->rects[object_id].y >> 4;
+        *q++ = (h->rects[object_id].y << 4) | ((y2 >> 8) & 0xf);
+        *q++ = y2;
+        
+        *q++ = 0x06;
+        // offset1, offset2
+        putbe16(&q, offset1[object_id]);
+        putbe16(&q, offset2[object_id]);
+    }
+    *q++ = 0x01; // start command
+    *q++ = 0xff; // terminating command
+
+    // send stop display command last
+    putbe16(&q, (h->end_display_time*90) >> 10);
+    putbe16(&q, (q - outbuf) - 2 /*+ 4*/);
+    *q++ = 0x02; // set end
+    *q++ = 0xff; // terminating command
+
+    qq = outbuf;
+    putbe16(&qq, q - outbuf);
+    
+    av_log(NULL, AV_LOG_DEBUG, "subtitle_packet size=%d\n", q - outbuf);
+    return q - outbuf;
+}
+
+static int dvdsub_init_encoder(AVCodecContext *avctx)
+{
+    return 0;
+}
+
+static int dvdsub_close_encoder(AVCodecContext *avctx)
+{
+    return 0;
+}
+
+static int dvdsub_encode(AVCodecContext *avctx,
+                         unsigned char *buf, int buf_size, void *data)
+{
+    //DVDSubtitleContext *s = avctx->priv_data;
+    AVSubtitle *sub = data;
+    int ret;
+
+    ret = encode_dvd_subtitles(buf, buf_size, sub);
+    return ret;
+}
+
+AVCodec dvdsub_encoder = {
+    "dvdsub",
+    CODEC_TYPE_SUBTITLE,
+    CODEC_ID_DVD_SUBTITLE,
+    sizeof(DVDSubtitleContext),
+    dvdsub_init_encoder,
+    dvdsub_encode,
+    dvdsub_close_encoder,
+};
+
+/* Local Variables: */
+/* c-basic-offset:4 */
+/* End: */