[FFmpeg-devel] [PATCH] avcodec: add HDMV Text Subtitle decoder
wm4
nfxjfg at googlemail.com
Tue Jan 31 17:42:54 EET 2017
On Tue, 31 Jan 2017 15:22:17 +0100
Paul B Mahol <onemda at gmail.com> wrote:
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
> libavcodec/Makefile | 2 +
> libavcodec/allcodecs.c | 2 +
> libavcodec/textst_parser.c | 49 ++++++++++++++++++++
> libavcodec/textstdec.c | 108 +++++++++++++++++++++++++++++++++++++++++++++
> libavformat/utils.c | 1 +
> 5 files changed, 162 insertions(+)
> create mode 100644 libavcodec/textst_parser.c
> create mode 100644 libavcodec/textstdec.c
>
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 43a6add..edadb0f 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -539,6 +539,7 @@ OBJS-$(CONFIG_SVQ1_ENCODER) += svq1enc.o svq1.o h263data.o \
> OBJS-$(CONFIG_SVQ3_DECODER) += svq3.o svq13.o mpegutils.o h264data.o
> OBJS-$(CONFIG_TEXT_DECODER) += textdec.o ass.o
> OBJS-$(CONFIG_TEXT_ENCODER) += srtenc.o ass_split.o
> +OBJS-$(CONFIG_TEXTST_DECODER) += textstdec.o ass.o
> OBJS-$(CONFIG_TAK_DECODER) += takdec.o tak.o takdsp.o
> OBJS-$(CONFIG_TARGA_DECODER) += targa.o
> OBJS-$(CONFIG_TARGA_ENCODER) += targaenc.o rle.o
> @@ -945,6 +946,7 @@ OBJS-$(CONFIG_RV30_PARSER) += rv34_parser.o
> OBJS-$(CONFIG_RV40_PARSER) += rv34_parser.o
> OBJS-$(CONFIG_SIPR_PARSER) += sipr_parser.o
> OBJS-$(CONFIG_TAK_PARSER) += tak_parser.o tak.o
> +OBJS-$(CONFIG_TEXTST_PARSER) += textst_parser.o
> OBJS-$(CONFIG_VC1_PARSER) += vc1_parser.o vc1.o vc1data.o \
> simple_idct.o wmv2data.o
> OBJS-$(CONFIG_VP3_PARSER) += vp3_parser.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index f92b2b7..9a90533 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -581,6 +581,7 @@ void avcodec_register_all(void)
> REGISTER_DECODER(SUBVIEWER, subviewer);
> REGISTER_DECODER(SUBVIEWER1, subviewer1);
> REGISTER_ENCDEC (TEXT, text);
> + REGISTER_DECODER(TEXTST, textst);
> REGISTER_DECODER(VPLAYER, vplayer);
> REGISTER_ENCDEC (WEBVTT, webvtt);
> REGISTER_ENCDEC (XSUB, xsub);
> @@ -704,6 +705,7 @@ void avcodec_register_all(void)
> REGISTER_PARSER(RV40, rv40);
> REGISTER_PARSER(SIPR, sipr);
> REGISTER_PARSER(TAK, tak);
> + REGISTER_PARSER(TEXTST, textst);
> REGISTER_PARSER(VC1, vc1);
> REGISTER_PARSER(VORBIS, vorbis);
> REGISTER_PARSER(VP3, vp3);
> diff --git a/libavcodec/textst_parser.c b/libavcodec/textst_parser.c
> new file mode 100644
> index 0000000..5079a96
> --- /dev/null
> +++ b/libavcodec/textst_parser.c
> @@ -0,0 +1,49 @@
> +/*
> + * 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
> + */
> +
> +/**
> + * @file
> + * HDMV TextST subtitle parser
> + */
> +
> +#include "libavutil/intreadwrite.h"
> +#include "parser.h"
> +
> +static int textst_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
> + const uint8_t **poutbuf, int *poutbuf_size,
> + const uint8_t *buf, int buf_size)
> +{
> + if (buf_size > 13) {
> + int64_t end;
> +
> + s1->pts = ((int64_t)(buf[3] & 1) << 32) | AV_RB32(&buf[4]);
> + end = ((int64_t)(buf[8] & 1) << 32) | AV_RB32(&buf[9]);
> + s1->duration = (end - s1->pts);
> + }
> +
> + /* always return the full packet. this parser isn't doing any splitting or
> + combining, only packet analysis */
> + *poutbuf = buf;
> + *poutbuf_size = buf_size;
> + return buf_size;
> +}
> +
> +AVCodecParser ff_textst_parser = {
> + .codec_ids = { AV_CODEC_ID_HDMV_TEXT_SUBTITLE },
> + .parser_parse = textst_parse,
> +};
Why does it need to be in a parser, instead of the demuxer? It seems
like this codec exists only in .ts anyway, and the way PTS/duration is
extracted seems very closely tied to the format.
> diff --git a/libavcodec/textstdec.c b/libavcodec/textstdec.c
> new file mode 100644
> index 0000000..a259d2d
> --- /dev/null
> +++ b/libavcodec/textstdec.c
> @@ -0,0 +1,108 @@
> +/*
> + * HDMV TextST decoder
> + * Copyright (c) 2017 Paul B Mahol
> + *
> + * 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 <string.h>
> +
> +#include "libavutil/bprint.h"
> +#include "avcodec.h"
> +#include "ass.h"
> +#include "bytestream.h"
> +
> +static int textst_event_to_ass(AVBPrint *buf, const char *p, int size)
> +{
> + GetByteContext gb;
> + int i, count;
> +
> + bytestream2_init(&gb, p, size);
> + count = bytestream2_get_byte(&gb);
> +
> + if (count > 127) {
> + int size = bytestream2_get_be16(&gb);
> + bytestream2_skip(&gb, size);
> + }
> + if (bytestream2_get_bytes_left(&gb) > 2) {
> + count = bytestream2_get_byte(&gb);
> +
> + for (i = 0; i < count; i++) {
> + int dlength;
> +
> + bytestream2_skip(&gb, 2);
> + dlength = bytestream2_get_be16(&gb);
> +
> + while (dlength > 3) {
> + int type, length;
> + int code = bytestream2_get_byte(&gb);
> +
> + dlength--;
> + if (code != 0x1b)
> + continue;
> +
> + type = bytestream2_get_byte(&gb);
> + length = bytestream2_get_byte(&gb);
> + dlength -= (2 + length);
> +
> + switch (type) {
> + case 1:
> + av_bprint_append_data(buf, gb.buffer, FFMIN(length, bytestream2_get_bytes_left(&gb)));
> + bytestream2_skip(&gb, length);
> + break;
> + case 0x0a:
> + av_bprintf(buf, "\n");
> + default:
> + bytestream2_skip(&gb, length);
> + break;
> + }
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int textst_decode_frame(AVCodecContext *avctx,
> + void *data, int *got_sub_ptr, AVPacket *avpkt)
> +{
> + FFASSDecoderContext *s = avctx->priv_data;
> + const char *ptr = avpkt->data;
> + AVSubtitle *sub = data;
> + AVBPrint buf;
> + int ret = 0;
> +
> + av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
> + if (ptr && avpkt->size > 13 && !textst_event_to_ass(&buf, ptr + 13, avpkt->size - 13))
> + ret = ff_ass_add_rect(sub, buf.str, s->readorder++, 0, NULL, NULL);
> + av_bprint_finalize(&buf, NULL);
> + if (ret < 0)
> + return ret;
> + *got_sub_ptr = sub->num_rects > 0;
> + return avpkt->size;
> +}
> +
> +AVCodec ff_textst_decoder = {
> + .name = "textst",
> + .long_name = NULL_IF_CONFIG_SMALL("HDMV TextST subtitle"),
> + .type = AVMEDIA_TYPE_SUBTITLE,
> + .id = AV_CODEC_ID_HDMV_TEXT_SUBTITLE,
> + .decode = textst_decode_frame,
> + .init = ff_ass_subtitle_header_default,
> + .flush = ff_ass_decoder_flush,
> + .priv_data_size = sizeof(FFASSDecoderContext),
> +};
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 0711310..74f808f 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -1445,6 +1445,7 @@ static int parse_packet(AVFormatContext *s, AVPacket *pkt, int stream_index)
>
> out_pkt.stream_index = st->index;
> out_pkt.pts = st->parser->pts;
> + out_pkt.duration = st->parser->duration;
> out_pkt.dts = st->parser->dts;
> out_pkt.pos = st->parser->pos;
>
This overwrites values written to out_pkt.duration above this code.
Does it even pass FATE?
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