On Thu, 11 Jul 2019, mikroh...@gmail.com wrote:
Current version of dvbsub encoder doesn't support HD DVB subtitles. The high
resolution bitmaps are muxed into the stream but without the DDS (display
definition segment) the players asume that the DVB subtitles are in SD
(720x576) resolution which causes them to either render the subtitles too large
and misplaced or don't render them at all. By including the DDS as defined in
section 7.7.1 of ETSI EN 300 743 (V1.3.1) this problem is fixed.
7.2.1 Display definition segment
The display definition for a subtitle service may be defined by the display
definition segment if present in the stream.
Absence of a DDS implies that the stream is coded in accordance with EN 300 743
(V1.2.1) [5] and that a display width of 720 pixels and a display height of 576
lines may be assumed.
https://www.etsi.org/deliver/etsi_en/300700_300799/300743/01.03.01_60/en_300743v010301p.pdf
Signed-off-by: Jernej Fijacko <mikroh...@gmail.com>
---
libavcodec/dvbsub.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/libavcodec/dvbsub.c b/libavcodec/dvbsub.c
index 8cce702..c838567 100644
--- a/libavcodec/dvbsub.c
+++ b/libavcodec/dvbsub.c
@@ -247,7 +247,8 @@ static void dvb_encode_rle8(uint8_t **pq,
*pq = q;
}
-static int encode_dvb_subtitles(DVBSubtitleContext *s,
+static int encode_dvb_subtitles(AVCodecContext *avctx,
+ DVBSubtitleContext *s,
uint8_t *outbuf, const AVSubtitle *h)
{
uint8_t *q, *pseg_len;
@@ -261,6 +262,19 @@ static int encode_dvb_subtitles(DVBSubtitleContext *s,
if (h->num_rects && !h->rects)
return -1;
+ if (avctx->width > 0 && avctx->height > 0) {
+ /* display definition segment */
+ *q++ = 0x0f; /* sync_byte */
+ *q++ = 0x14; /* segment_type */
+ bytestream_put_be16(&q, page_id);
+ pseg_len = q;
+ q += 2; /* segment length */
+ *q++ = 0x20; /* dds version number & display window flag */
I guess 2 is the version number, right? Why 2?
+ bytestream_put_be16(&q, avctx->width - 1); /* display width */
+ bytestream_put_be16(&q, avctx->height - 1); /* display height */
+ bytestream_put_be16(&pseg_len, q - pseg_len - 2);
+ }
+
/* page composition segment */
*q++ = 0x0f; /* sync_byte */
@@ -449,7 +463,7 @@ static int dvbsub_encode(AVCodecContext *avctx,
DVBSubtitleContext *s = avctx->priv_data;
int ret;
- ret = encode_dvb_subtitles(s, buf, sub);
+ ret = encode_dvb_subtitles(avctx, s, buf, sub);
You could pass avctx only and assign s the same way as it is assigned
here...
return ret;
Otherwise looks good.
Thanks,
Marton
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