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mpv/sub/lavc_conv.c

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/*
* This file is part of mpv.
*
* mpv 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.
*
* mpv 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 mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <assert.h>
#include <libavcodec/avcodec.h>
#include <libavutil/intreadwrite.h>
#include <libavutil/common.h>
#include <libavutil/opt.h>
#include "mpv_talloc.h"
#include "common/msg.h"
#include "common/av_common.h"
#include "demux/stheader.h"
#include "misc/bstr.h"
#include "sd.h"
struct lavc_conv {
struct mp_log *log;
AVCodecContext *avctx;
AVPacket *avpkt;
AVPacket *avpkt_vtt;
char *codec;
char *extradata;
AVSubtitle cur;
char **cur_list;
};
static const char *get_lavc_format(const char *format)
{
// For the hack involving parse_webvtt().
if (format && strcmp(format, "webvtt-webm") == 0)
format = "webvtt";
// Most text subtitles are srt/html style anyway.
if (format && strcmp(format, "text") == 0)
format = "subrip";
return format;
}
// Disable style definitions generated by the libavcodec converter.
// We always want the user defined style instead.
static void disable_styles(bstr header)
{
bstr style = bstr0("\nStyle: ");
while (header.len) {
int n = bstr_find(header, style);
if (n < 0)
break;
header.start[n + 1] = '#'; // turn into a comment
header = bstr_cut(header, n + style.len);
}
}
struct lavc_conv *lavc_conv_create(struct mp_log *log,
const struct mp_codec_params *mp_codec)
{
struct lavc_conv *priv = talloc_zero(NULL, struct lavc_conv);
priv->log = log;
priv->cur_list = talloc_array(priv, char*, 0);
priv->codec = talloc_strdup(priv, mp_codec->codec);
AVCodecContext *avctx = NULL;
AVDictionary *opts = NULL;
const char *fmt = get_lavc_format(priv->codec);
const AVCodec *codec = avcodec_find_decoder(mp_codec_to_av_codec_id(fmt));
if (!codec)
goto error;
avctx = avcodec_alloc_context3(codec);
if (!avctx)
goto error;
if (mp_set_avctx_codec_headers(avctx, mp_codec) < 0)
goto error;
priv->avpkt = av_packet_alloc();
priv->avpkt_vtt = av_packet_alloc();
if (!priv->avpkt || !priv->avpkt_vtt)
goto error;
#if LIBAVCODEC_VERSION_MAJOR < 59
av_dict_set(&opts, "sub_text_format", "ass", 0);
#endif
av_dict_set(&opts, "flags2", "+ass_ro_flush_noop", 0);
if (strcmp(priv->codec, "eia_608") == 0)
av_dict_set(&opts, "real_time", "1", 0);
if (avcodec_open2(avctx, codec, &opts) < 0)
goto error;
av_dict_free(&opts);
// Documented as "set by libavcodec", but there is no other way
avctx->time_base = (AVRational) {1, 1000};
avctx->pkt_timebase = avctx->time_base;
avctx->sub_charenc_mode = FF_SUB_CHARENC_MODE_IGNORE;
priv->avctx = avctx;
priv->extradata = talloc_strndup(priv, avctx->subtitle_header,
avctx->subtitle_header_size);
disable_styles(bstr0(priv->extradata));
return priv;
error:
MP_FATAL(priv, "Could not open libavcodec subtitle converter\n");
av_dict_free(&opts);
av_free(avctx);
mp_free_av_packet(&priv->avpkt);
mp_free_av_packet(&priv->avpkt_vtt);
talloc_free(priv);
return NULL;
}
char *lavc_conv_get_extradata(struct lavc_conv *priv)
{
return priv->extradata;
}
// FFmpeg WebVTT packets are pre-parsed in some way. The FFmpeg Matroska
// demuxer does this on its own. In order to free our demuxer_mkv.c from
// codec-specific crud, we do this here.
// Copied from libavformat/matroskadec.c (FFmpeg 818ebe9 / 2013-08-19)
// License: LGPL v2.1 or later
// Author header: The FFmpeg Project
// Modified in some ways.
static int parse_webvtt(AVPacket *in, AVPacket *pkt)
{
uint8_t *id, *settings, *text, *buf;
int id_len, settings_len, text_len;
uint8_t *p, *q;
int err;
uint8_t *data = in->data;
int data_len = in->size;
if (data_len <= 0)
return AVERROR_INVALIDDATA;
p = data;
q = data + data_len;
id = p;
id_len = -1;
while (p < q) {
if (*p == '\r' || *p == '\n') {
id_len = p - id;
if (*p == '\r')
p++;
break;
}
p++;
}
if (p >= q || *p != '\n')
return AVERROR_INVALIDDATA;
p++;
settings = p;
settings_len = -1;
while (p < q) {
if (*p == '\r' || *p == '\n') {
settings_len = p - settings;
if (*p == '\r')
p++;
break;
}
p++;
}
if (p >= q || *p != '\n')
return AVERROR_INVALIDDATA;
p++;
text = p;
text_len = q - p;
while (text_len > 0) {
const int len = text_len - 1;
const uint8_t c = p[len];
if (c != '\r' && c != '\n')
break;
text_len = len;
}
if (text_len <= 0)
return AVERROR_INVALIDDATA;
err = av_new_packet(pkt, text_len);
if (err < 0)
return AVERROR(err);
memcpy(pkt->data, text, text_len);
if (id_len > 0) {
buf = av_packet_new_side_data(pkt,
AV_PKT_DATA_WEBVTT_IDENTIFIER,
id_len);
if (buf == NULL) {
av_packet_unref(pkt);
return AVERROR(ENOMEM);
}
memcpy(buf, id, id_len);
}
if (settings_len > 0) {
buf = av_packet_new_side_data(pkt,
AV_PKT_DATA_WEBVTT_SETTINGS,
settings_len);
if (buf == NULL) {
av_packet_unref(pkt);
return AVERROR(ENOMEM);
}
memcpy(buf, settings, settings_len);
}
pkt->pts = in->pts;
pkt->duration = in->duration;
return 0;
}
// Return a NULL-terminated list of ASS event lines and have
// the AVSubtitle display PTS and duration set to input
// double variables.
char **lavc_conv_decode(struct lavc_conv *priv, struct demux_packet *packet,
double *sub_pts, double *sub_duration)
{
AVCodecContext *avctx = priv->avctx;
AVPacket *curr_pkt = priv->avpkt;
int ret, got_sub;
int num_cur = 0;
avsubtitle_free(&priv->cur);
mp_set_av_packet(priv->avpkt, packet, &avctx->time_base);
if (priv->avpkt->pts < 0)
priv->avpkt->pts = 0;
if (strcmp(priv->codec, "webvtt-webm") == 0) {
if (parse_webvtt(priv->avpkt, priv->avpkt_vtt) < 0) {
MP_ERR(priv, "Error parsing subtitle\n");
goto done;
}
curr_pkt = priv->avpkt_vtt;
}
ret = avcodec_decode_subtitle2(avctx, &priv->cur, &got_sub, curr_pkt);
if (ret < 0) {
MP_ERR(priv, "Error decoding subtitle\n");
} else if (got_sub) {
*sub_pts = packet->pts + mp_pts_from_av(priv->cur.start_display_time,
&avctx->time_base);
*sub_duration = priv->cur.end_display_time == UINT32_MAX ?
UINT32_MAX :
mp_pts_from_av(priv->cur.end_display_time -
priv->cur.start_display_time,
&avctx->time_base);
for (int i = 0; i < priv->cur.num_rects; i++) {
if (priv->cur.rects[i]->w > 0 && priv->cur.rects[i]->h > 0)
MP_WARN(priv, "Ignoring bitmap subtitle.\n");
char *ass_line = priv->cur.rects[i]->ass;
if (!ass_line)
continue;
MP_TARRAY_APPEND(priv, priv->cur_list, num_cur, ass_line);
}
}
done:
av_packet_unref(priv->avpkt_vtt);
MP_TARRAY_APPEND(priv, priv->cur_list, num_cur, NULL);
return priv->cur_list;
}
void lavc_conv_reset(struct lavc_conv *priv)
{
avcodec_flush_buffers(priv->avctx);
}
void lavc_conv_uninit(struct lavc_conv *priv)
{
avsubtitle_free(&priv->cur);
avcodec_free_context(&priv->avctx);
mp_free_av_packet(&priv->avpkt);
mp_free_av_packet(&priv->avpkt_vtt);
talloc_free(priv);
}
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