[FFmpeg-devel] [PATCH]Basic XSUB encoder (take 5)
Björn Axelsson
gecko
Thu Feb 5 22:45:25 CET 2009
On Thu, 5 Feb 2009, Reimar D?ffinger wrote:
> On Thu, Feb 05, 2009 at 10:04:18PM +0100, Bj?rn Axelsson wrote:
> > + // Enforce total height to be be multiple of 2
> > + if (h->rects[0]->h & 1)
> > + put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);
>
> Is there a buffer size check for that line of code?
Yes, it is hidden in the call to init_put_bits().
Comment added for some additional clarity.
> > + flush_put_bits(&pb);
> > +
> > + return hdr - buf + put_bits_count(&pb)/8;
>
> You need another align_put_bits or you might return one too few here.
Oops.
> I think I have no further comment, I'd appreciate if others could review
> the build system and other stuff...
Thank you for your time.
I still need some help solving the timestamp problem as I don't think the
hack used in the patch is acceptable.
--
Bj?rn Axelsson
-------------- next part --------------
Index: ffmpeg.c
===================================================================
--- ffmpeg.c.orig 2009-02-05 21:17:02.000000000 +0100
+++ ffmpeg.c 2009-02-05 21:17:36.000000000 +0100
@@ -814,6 +814,7 @@
nb = 1;
for(i = 0; i < nb; i++) {
+ sub->pts = av_rescale_q(pts, ist->st->time_base, AV_TIME_BASE_Q);
subtitle_out_size = avcodec_encode_subtitle(enc, subtitle_out,
subtitle_out_max_size, sub);
Index: libavcodec/Makefile
===================================================================
--- libavcodec/Makefile.orig 2009-02-05 21:17:11.000000000 +0100
+++ libavcodec/Makefile 2009-02-05 21:17:36.000000000 +0100
@@ -252,6 +252,7 @@
OBJS-$(CONFIG_XAN_WC4_DECODER) += xan.o
OBJS-$(CONFIG_XL_DECODER) += xl.o
OBJS-$(CONFIG_XSUB_DECODER) += xsubdec.o
+OBJS-$(CONFIG_XSUB_ENCODER) += xsubenc.o
OBJS-$(CONFIG_XVMC) += xvmcvideo.o
OBJS-$(CONFIG_ZLIB_DECODER) += lcldec.o
OBJS-$(CONFIG_ZLIB_ENCODER) += lclenc.o
Index: libavcodec/xsubenc.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ libavcodec/xsubenc.c 2009-02-05 22:40:30.000000000 +0100
@@ -0,0 +1,214 @@
+/*
+ * DivX (XSUB) subtitle encoder
+ * Copyright (c) 2005 DivX, Inc.
+ * Copyright (c) 2009 Bjorn Axelsson
+ *
+ * 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
+ */
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "bitstream.h"
+
+/* For obscure reasons we pad the subtitles with two pixels on either side */
+#define PADDING 2
+#define PADDING_COLOR 0
+
+/** Encode a single color run. At most 16 bits will be used. */
+static void put_xsub_rle(PutBitContext *pb, int len, int color)
+{
+ if (len <= 255)
+ put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);
+ else
+ put_bits(pb, 14, 0);
+ put_bits(pb, 2, color);
+}
+
+/** Encode a 4-colour bitmap with XSUB rle.
+ * The encoded bitmap may be wider than the source bitmap due to padding. */
+static int xsub_encode_rle(PutBitContext *pb,
+ const uint8_t *bitmap, int linesize, int w, int h)
+{
+ int x0, x1, y, len, color = PADDING_COLOR;
+
+ for (y = 0; y < h; y++) {
+ x0 = 0;
+ while (x0 < w) {
+ // Make sure we have enough room for at least one run and padding
+ if (pb->size_in_bits - put_bits_count(pb) < 7*8)
+ return -1;
+
+ x1 = x0;
+ color = bitmap[x1++] & 3;
+ while (x1 < w && (bitmap[x1] & 3) == color)
+ x1++;
+ len = x1 - x0;
+ if (PADDING && x0 == 0) {
+ if (color == PADDING_COLOR) {
+ len += PADDING;
+ x0 -= PADDING;
+ } else
+ put_xsub_rle(pb, PADDING, PADDING_COLOR);
+ }
+
+ // Run can't be longer than 255, unless it is the rest of a row
+ if (x1 == w && color == PADDING_COLOR)
+ len += PADDING + (w&1);
+ else
+ len = FFMIN(len, 255);
+ put_xsub_rle(pb, len, color);
+
+ x0 += len;
+ }
+ if (color != PADDING_COLOR && (PADDING || (w&1)))
+ put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);
+
+ align_put_bits(pb);
+
+ bitmap += linesize;
+ }
+
+ return 0;
+}
+
+static const int tc_divs[3] = { 1000, 60, 60 };
+static int make_tc(uint64_t ms, int *tc)
+{
+ int i;
+ for (i=0; i<3; i++) {
+ tc[i] = ms % tc_divs[i];
+ ms /= tc_divs[i];
+ }
+ tc[3] = ms;
+ return ms > 99;
+}
+
+static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,
+ int bufsize, void *data)
+{
+ AVSubtitle *h = (AVSubtitle *)data;
+ uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
+ uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
+ int start_tc[4], end_tc[4];
+ uint8_t *hdr = (uint8_t *)buf + 27; // Point behind the timestamp
+ uint8_t *rlelenptr;
+ uint16_t width, height;
+ int i;
+ PutBitContext pb;
+
+ if (h->num_rects == 0 || h->rects == NULL)
+ return -1;
+
+ if (bufsize < 27 + 7*2 + 4*3) {
+ av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
+ return -1;
+ }
+
+ // TODO: support multiple rects
+ if (h->num_rects > 1)
+ av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);
+
+ // TODO: render text-based subtitles into bitmaps
+ if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) {
+ av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
+ return -1;
+ }
+
+ // TODO: color reduction, similar to dvdsub encoder
+ if (h->rects[0]->nb_colors > 4)
+ av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);
+
+ // TODO: Palette swapping if color zero is not transparent
+ if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff)
+ av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");
+
+ if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
+ av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
+ return -1;
+ }
+
+ snprintf(buf, 28,
+ "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
+ start_tc[3], start_tc[2], start_tc[1], start_tc[0],
+ end_tc[3], end_tc[3], end_tc[1], end_tc[0]);
+
+ // Width and height must probably be multiples of 2.
+ // 2 pixels required on either side of subtitle.
+ // Possibly due to limitations of hardware renderers.
+ // TODO: check if the bitmap is already padded
+ width = ((h->rects[0]->w + 1) & ~1) + PADDING * 2;
+ height = (h->rects[0]->h + 1) & ~1;
+
+ bytestream_put_le16(&hdr, width);
+ bytestream_put_le16(&hdr, height);
+ bytestream_put_le16(&hdr, h->rects[0]->x);
+ bytestream_put_le16(&hdr, h->rects[0]->y);
+ bytestream_put_le16(&hdr, h->rects[0]->x + width);
+ bytestream_put_le16(&hdr, h->rects[0]->y + height);
+
+ rlelenptr = hdr; // Will store length of first field here later.
+ hdr+=2;
+
+ // Palette
+ for (i=0; i<4; i++)
+ bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]);
+
+ // Bitmap
+ // RLE buffer. Reserve 2 bytes for possible padding after the last row.
+ init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);
+ if (xsub_encode_rle(&pb,
+ h->rects[0]->pict.data[0],
+ h->rects[0]->pict.linesize[0]*2,
+ h->rects[0]->w, (h->rects[0]->h + 1) / 2))
+ return -1;
+ bytestream_put_le16(&rlelenptr, put_bits_count(&pb)/8); // Len of first field
+
+ if (xsub_encode_rle(&pb,
+ h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0],
+ h->rects[0]->pict.linesize[0]*2,
+ h->rects[0]->w, h->rects[0]->h / 2))
+ return -1;
+
+ // Enforce total height to be be multiple of 2
+ if (h->rects[0]->h & 1) {
+ put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);
+ align_put_bits(&pb);
+ }
+
+ flush_put_bits(&pb);
+
+ return hdr - buf + put_bits_count(&pb)/8;
+}
+
+static av_cold int xsub_encoder_init(AVCodecContext *avctx)
+{
+ if (!avctx->codec_tag)
+ avctx->codec_tag = MKTAG('D','X','S','B');
+
+ return 0;
+}
+
+AVCodec xsub_encoder = {
+ "xsub",
+ CODEC_TYPE_SUBTITLE,
+ CODEC_ID_XSUB,
+ 0,
+ xsub_encoder_init,
+ xsub_encode,
+ NULL,
+ .long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"),
+};
Index: libavcodec/allcodecs.c
===================================================================
--- libavcodec/allcodecs.c.orig 2009-02-05 21:17:11.000000000 +0100
+++ libavcodec/allcodecs.c 2009-02-05 21:17:36.000000000 +0100
@@ -283,7 +283,7 @@
/* subtitles */
REGISTER_ENCDEC (DVBSUB, dvbsub);
REGISTER_ENCDEC (DVDSUB, dvdsub);
- REGISTER_DECODER (XSUB, xsub);
+ REGISTER_ENCDEC (XSUB, xsub);
/* external libraries */
REGISTER_ENCDEC (LIBAMR_NB, libamr_nb);
Index: libavcodec/avcodec.h
===================================================================
--- libavcodec/avcodec.h.orig 2009-02-05 21:17:11.000000000 +0100
+++ libavcodec/avcodec.h 2009-02-05 21:18:31.000000000 +0100
@@ -30,7 +30,7 @@
#include "libavutil/avutil.h"
#define LIBAVCODEC_VERSION_MAJOR 52
-#define LIBAVCODEC_VERSION_MINOR 12
+#define LIBAVCODEC_VERSION_MINOR 13
#define LIBAVCODEC_VERSION_MICRO 0
#define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
@@ -2432,6 +2432,7 @@
uint32_t end_display_time; /* relative to packet pts, in ms */
unsigned num_rects;
AVSubtitleRect **rects;
+ uint64_t pts; ///< Same as packet pts, in AV_TIME_BASE
} AVSubtitle;
Index: libavformat/avienc.c
===================================================================
--- libavformat/avienc.c.orig 2009-02-05 21:17:03.000000000 +0100
+++ libavformat/avienc.c 2009-02-05 21:17:36.000000000 +0100
@@ -82,6 +82,9 @@
if (type == CODEC_TYPE_VIDEO) {
tag[2] = 'd';
tag[3] = 'c';
+ } else if (type == CODEC_TYPE_SUBTITLE) {
+ tag[2] = 's';
+ tag[3] = 'b';
} else {
tag[2] = 'w';
tag[3] = 'b';
@@ -213,8 +216,10 @@
case CODEC_TYPE_AUDIO: put_tag(pb, "auds"); break;
// case CODEC_TYPE_TEXT : put_tag(pb, "txts"); break;
case CODEC_TYPE_DATA : put_tag(pb, "dats"); break;
+ case CODEC_TYPE_SUBTITLE: put_tag(pb, "vids"); break;
}
- if(stream->codec_type == CODEC_TYPE_VIDEO)
+ if(stream->codec_type == CODEC_TYPE_VIDEO
+ || stream->codec_type == CODEC_TYPE_SUBTITLE)
put_le32(pb, stream->codec_tag);
else
put_le32(pb, 1);
@@ -254,6 +259,7 @@
strf = start_tag(pb, "strf");
switch(stream->codec_type) {
case CODEC_TYPE_VIDEO:
+ case CODEC_TYPE_SUBTITLE:
put_bmp_header(pb, stream, codec_bmp_tags, 0);
break;
case CODEC_TYPE_AUDIO:
Index: Changelog
===================================================================
--- Changelog.orig 2009-02-05 21:17:12.000000000 +0100
+++ Changelog 2009-02-05 21:19:21.000000000 +0100
@@ -147,6 +147,7 @@
- R3D REDCODE demuxer
- ALSA support for playback and record
- Electronic Arts TQI decoder
+- DivX (XSUB) subtitle encoder
version 0.4.9-pre1:
Index: doc/general.texi
===================================================================
--- doc/general.texi.orig 2009-02-05 21:17:12.000000000 +0100
+++ doc/general.texi 2009-02-05 21:17:36.000000000 +0100
@@ -456,7 +456,7 @@
@item ASS/SSA @tab X @tab X
@item DVB @tab X @tab X @tab X @tab X @tab X
@item DVD @tab X @tab X @tab X @tab X @tab X
- at item XSUB @tab @tab @tab @tab X @tab
+ at item XSUB @tab @tab @tab X @tab X @tab
@end multitable
@code{X} means that the feature is supported.
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