mpv/sub/sd_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 General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU 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 "config.h"
#include "talloc.h"
#include "common/msg.h"
#include "common/av_common.h"
#include "misc/bstr.h"
#include "sd.h"
#define HAVE_AV_WEBVTT (LIBAVCODEC_VERSION_MICRO >= 100)
struct sd_lavc_priv {
AVCodecContext *avctx;
};
static const char *get_lavc_format(const char *format)
{
// For the hack involving parse_webvtt().
if (format && strcmp(format, "webvtt-webm") == 0)
format = "webvtt";
return format;
}
static bool supports_format(const char *format)
{
format = get_lavc_format(format);
enum AVCodecID cid = mp_codec_to_av_codec_id(format);
AVCodec *codec = avcodec_find_decoder(cid);
const AVCodecDescriptor *desc = avcodec_descriptor_get(cid);
return codec && desc && desc->type == AVMEDIA_TYPE_SUBTITLE;
}
// Disable style definitions generated by the libavcodec converter.
// We always want the user defined style instead.
static void disable_styles(bstr header)
{
while (header.len) {
int n = bstr_find(header, bstr0("\nStyle: "));
if (n < 0)
break;
header.start[n + 1] = '#'; // turn into a comment
header = bstr_cut(header, 2);
}
}
static int init(struct sd *sd)
{
struct sd_lavc_priv *priv = talloc_zero(NULL, struct sd_lavc_priv);
AVCodecContext *avctx = NULL;
const char *fmt = get_lavc_format(sd->codec);
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;
avctx->extradata_size = sd->extradata_len;
avctx->extradata = sd->extradata;
if (avcodec_open2(avctx, codec, NULL) < 0)
goto error;
// Documented as "set by libavcodec", but there is no other way
avctx->time_base = (AVRational) {1, 1000};
priv->avctx = avctx;
sd->priv = priv;
sd->output_codec = "ssa";
sd->output_extradata = avctx->subtitle_header;
sd->output_extradata_len = avctx->subtitle_header_size;
if (sd->output_extradata) {
sd->output_extradata = talloc_memdup(sd, sd->output_extradata,
sd->output_extradata_len);
disable_styles((bstr){sd->output_extradata, sd->output_extradata_len});
}
return 0;
error:
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MP_FATAL(sd, "Could not open libavcodec subtitle converter\n");
av_free(avctx);
talloc_free(priv);
return -1;
}
#if HAVE_AV_WEBVTT
// 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_free_packet(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_free_packet(pkt);
return AVERROR(ENOMEM);
}
memcpy(buf, settings, settings_len);
}
pkt->pts = in->pts;
pkt->duration = in->duration;
pkt->convergence_duration = in->convergence_duration;
return 0;
}
#else
static int parse_webvtt(AVPacket *in, AVPacket *pkt)
{
return -1;
}
#endif
static void decode(struct sd *sd, struct demux_packet *packet)
{
struct sd_lavc_priv *priv = sd->priv;
AVCodecContext *avctx = priv->avctx;
AVSubtitle sub = {0};
AVPacket pkt;
AVPacket parsed_pkt = {0};
int ret, got_sub;
mp_set_av_packet(&pkt, packet, &avctx->time_base);
if (sd->codec && strcmp(sd->codec, "webvtt-webm") == 0) {
if (parse_webvtt(&pkt, &parsed_pkt) < 0) {
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MP_ERR(sd, "Error parsing subtitle\n");
goto done;
}
pkt = parsed_pkt;
}
ret = avcodec_decode_subtitle2(avctx, &sub, &got_sub, &pkt);
if (ret < 0) {
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MP_ERR(sd, "Error decoding subtitle\n");
} else if (got_sub) {
for (int i = 0; i < sub.num_rects; i++) {
if (sub.rects[i]->w > 0 && sub.rects[i]->h > 0)
MP_WARN(sd, "Ignoring bitmap subtitle.\n");
char *ass_line = sub.rects[i]->ass;
if (!ass_line)
break;
// This might contain embedded timestamps, using the "old" ffmpeg
// ASS packet format, in which case pts/duration might be ignored
// at a later point.
sd_conv_add_packet(sd, ass_line, strlen(ass_line),
packet->pts, packet->duration);
}
}
done:
avsubtitle_free(&sub);
av_free_packet(&parsed_pkt);
}
static void reset(struct sd *sd)
{
struct sd_lavc_priv *priv = sd->priv;
avcodec_flush_buffers(priv->avctx);
sd_conv_def_reset(sd);
}
static void uninit(struct sd *sd)
{
struct sd_lavc_priv *priv = sd->priv;
avcodec_close(priv->avctx);
av_free(priv->avctx);
talloc_free(priv);
}
const struct sd_functions sd_lavc_conv = {
.name = "lavc_conv",
.supports_format = supports_format,
.init = init,
.decode = decode,
.get_converted = sd_conv_def_get_converted,
.reset = reset,
.uninit = uninit,
};