[FFmpeg-cvslog] avcodec/libzvbi-teletextdec: propagate ERASE_PAGE flag for repeated subtitle page headers
Marton Balint
git at videolan.org
Wed Jun 20 23:43:04 EEST 2018
ffmpeg | branch: master | Marton Balint <cus at passwd.hu> | Mon Jun 11 00:53:13 2018 +0200| [b1e0e216462a989a39e7b413aef6d32f8cedc154] | committer: Marton Balint
avcodec/libzvbi-teletextdec: propagate ERASE_PAGE flag for repeated subtitle page headers
This works around a libzvbi bug (a corner case in the teletext spec):
https://sourceforge.net/p/zapping/bugs/203/
https://sourceforge.net/p/zapping/patches/20/
Fixes samples/ffmpeg-bugs/trac/ticket2086/RBT_20100801_1835.ts.
Signed-off-by: Marton Balint <cus at passwd.hu>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b1e0e216462a989a39e7b413aef6d32f8cedc154
---
libavcodec/libzvbi-teletextdec.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/libavcodec/libzvbi-teletextdec.c b/libavcodec/libzvbi-teletextdec.c
index ccded23e7c..809547545b 100644
--- a/libavcodec/libzvbi-teletextdec.c
+++ b/libavcodec/libzvbi-teletextdec.c
@@ -74,6 +74,8 @@ typedef struct TeletextContext
int readorder;
uint8_t subtitle_map[2048];
+ int last_pgno;
+ int last_p5;
} TeletextContext;
static int chop_spaces_utf8(const unsigned char* t, int len)
@@ -372,6 +374,17 @@ static int slice_to_vbi_lines(TeletextContext *ctx, uint8_t* buf, int size)
int pgno = ((pmag & 7) << 8) + page;
// Check for disabled NEWSFLASH flag and enabled SUBTITLE and SUPRESS_HEADER flags
ctx->subtitle_map[pgno] = (!(flags1 & 0x40) && flags1 & 0x80 && flags2 & 0x01);
+ // Propagate ERASE_PAGE flag for repeated page headers to work around a libzvbi bug
+ if (ctx->subtitle_map[pgno] && pgno == ctx->last_pgno) {
+ int last_byte9 = vbi_unham8(ctx->last_p5);
+ if (last_byte9 >= 0 && last_byte9 & 0x8) {
+ int byte9 = vbi_unham8(p[5]);
+ if (byte9 >= 0)
+ p[5] = vbi_ham8(byte9 | 0x8);
+ }
+ }
+ ctx->last_pgno = pgno;
+ ctx->last_p5 = p[5];
}
}
lines++;
@@ -494,6 +507,7 @@ static int teletext_init_decoder(AVCodecContext *avctx)
ctx->vbi = NULL;
ctx->pts = AV_NOPTS_VALUE;
+ ctx->last_pgno = -1;
if (ctx->opacity == -1)
ctx->opacity = ctx->transparent_bg ? 0 : 255;
@@ -514,6 +528,7 @@ static int teletext_close_decoder(AVCodecContext *avctx)
vbi_decoder_delete(ctx->vbi);
ctx->vbi = NULL;
ctx->pts = AV_NOPTS_VALUE;
+ ctx->last_pgno = -1;
memset(ctx->subtitle_map, 0, sizeof(ctx->subtitle_map));
if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
ctx->readorder = 0;
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