[FFmpeg-devel] [PATCH 2/2] avformat/hls: Add subtitle support
Franklin Phillips
franklinphillips at gmx.com
Fri Dec 30 22:10:05 EET 2016
Each subtile segment is a WebVTT file and needs to be demuxed
separately. These segments also contain a header to synchronize their
timing with the MPEG TS stream so those timestamps are requested from
the WebVTT demuxer through an AVOption.
Signed-off-by: Franklin Phillips <franklinphillips at gmx.com>
---
libavformat/hls.c | 196 ++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 138 insertions(+), 58 deletions(-)
diff --git a/libavformat/hls.c b/libavformat/hls.c
index 3ae3c7c..278c3b2 100644
--- a/libavformat/hls.c
+++ b/libavformat/hls.c
@@ -153,6 +153,8 @@ struct playlist {
* playlist, if any. */
int n_init_sections;
struct segment **init_sections;
+
+ int is_subtitle; /* Indicates if it's a subtitle playlist */
};
/*
@@ -203,6 +205,7 @@ typedef struct HLSContext {
char *headers; ///< holds HTTP headers set as an AVOption to the HTTP protocol context
char *http_proxy; ///< holds the address of the HTTP proxy server
AVDictionary *avio_opts;
+ AVDictionary *demuxer_opts;
int strict_std_compliance;
} HLSContext;
@@ -309,6 +312,8 @@ static struct playlist *new_playlist(HLSContext *c, const char *url,
ff_make_absolute_url(pls->url, sizeof(pls->url), base, url);
pls->seek_timestamp = AV_NOPTS_VALUE;
+ pls->is_subtitle = 0;
+
pls->is_id3_timestamped = -1;
pls->id3_mpegts_timestamp = AV_NOPTS_VALUE;
@@ -482,11 +487,6 @@ static struct rendition *new_rendition(HLSContext *c, struct rendition_info *inf
if (type == AVMEDIA_TYPE_SUBTITLE && !info->uri[0])
return NULL;
- /* TODO: handle subtitles (each segment has to parsed separately) */
- if (c->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL)
- if (type == AVMEDIA_TYPE_SUBTITLE)
- return NULL;
-
rend = av_mallocz(sizeof(struct rendition));
if (!rend)
return NULL;
@@ -501,9 +501,14 @@ static struct rendition *new_rendition(HLSContext *c, struct rendition_info *inf
/* add the playlist if this is an external rendition */
if (info->uri[0]) {
rend->playlist = new_playlist(c, info->uri, url_base);
- if (rend->playlist)
+ if (rend->playlist) {
dynarray_add(&rend->playlist->renditions,
&rend->playlist->n_renditions, rend);
+ if (type == AVMEDIA_TYPE_SUBTITLE) {
+ rend->playlist->is_subtitle = 1;
+ rend->playlist->is_id3_timestamped = 0;
+ }
+ }
}
if (info->assoc_language[0]) {
@@ -1241,8 +1246,103 @@ static int read_data(void *opaque, uint8_t *buf, int buf_size)
{
struct playlist *v = opaque;
HLSContext *c = v->parent->priv_data;
- int ret, i;
- int just_opened = 0;
+ int ret, just_opened = 0;
+ struct segment *seg;
+
+ if (v->cur_seq_no - v->start_seq_no >= v->n_segments) {
+ return AVERROR_EOF;
+ } else {
+ seg = current_segment(v);
+ }
+
+ if (!v->input) {
+ /* load/update Media Initialization Section, if any */
+ ret = update_init_section(v, seg);
+ if (ret < 0)
+ return ret;
+
+ ret = open_input(c, v, seg);
+ if (ret < 0) {
+ if (ff_check_interrupt(c->interrupt_callback))
+ return AVERROR_EXIT;
+ av_log(v->parent, AV_LOG_WARNING, "Failed to open segment of playlist %d\n",
+ v->index);
+ return ret;
+ }
+ just_opened = 1;
+ }
+
+ if (v->init_sec_buf_read_offset < v->init_sec_data_len) {
+ /* Push init section out first before first actual segment */
+ int copy_size = FFMIN(v->init_sec_data_len - v->init_sec_buf_read_offset, buf_size);
+ memcpy(buf, v->init_sec_buf, copy_size);
+ v->init_sec_buf_read_offset += copy_size;
+ return copy_size;
+ }
+
+ ret = read_from_url(v, seg, buf, buf_size, READ_NORMAL);
+ if (ret > 0) {
+ if (just_opened && v->is_id3_timestamped != 0) {
+ /* Intercept ID3 tags here, elementary audio streams are required
+ * to convey timestamps using them in the beginning of each segment. */
+ intercept_id3(v, buf, buf_size, &ret);
+ }
+ }
+
+ return ret;
+}
+
+static int nested_io_open(AVFormatContext *s, AVIOContext **pb, const char *url,
+ int flags, AVDictionary **opts)
+{
+ av_log(s, AV_LOG_ERROR,
+ "A HLS playlist item '%s' referred to an external file '%s'. "
+ "Opening this file was forbidden for security reasons\n",
+ s->filename, url);
+ return AVERROR(EPERM);
+}
+
+static int init_subtitle_context(struct playlist *pls)
+{
+ HLSContext *c = pls->parent->priv_data;
+ AVInputFormat *in_fmt;
+ AVDictionary *opts = NULL;
+ int ret = 0;
+
+ if (!(pls->ctx = avformat_alloc_context()))
+ return AVERROR(ENOMEM);
+
+ pls->read_buffer = av_malloc(INITIAL_BUFFER_SIZE);
+ if (!pls->read_buffer) {
+ avformat_free_context(pls->ctx);
+ pls->ctx = NULL;
+ return AVERROR(ENOMEM);
+ }
+
+ ffio_init_context(&pls->pb, pls->read_buffer, INITIAL_BUFFER_SIZE, 0, pls,
+ read_data, NULL, NULL);
+ pls->pb.seekable = 0;
+ pls->ctx->pb = &pls->pb;
+ pls->ctx->io_open = nested_io_open;
+
+ ret = ff_copy_whiteblacklists(pls->ctx, pls->parent);
+ if (ret < 0)
+ return ret;
+
+ in_fmt = av_find_input_format("webvtt");
+ av_dict_copy(&opts, c->demuxer_opts, 0);
+ ret = avformat_open_input(&pls->ctx, current_segment(pls)->url, in_fmt, &opts);
+ av_dict_free(&opts);
+ if (ret < 0)
+ return ret;
+
+ return ret;
+}
+
+static int read_packet(struct playlist *v, AVPacket *pkt)
+{
+ HLSContext *c = v->parent->priv_data;
+ int ret;
restart:
if (!v->needed)
@@ -1250,11 +1350,11 @@ restart:
if (!v->input) {
int64_t reload_interval;
- struct segment *seg;
/* Check that the playlist is still needed before opening a new
* segment. */
- if (v->ctx && v->ctx->nb_streams) {
+ if ((v->ctx && v->ctx->nb_streams) || v->is_subtitle) {
+ int i;
v->needed = 0;
for (i = 0; i < v->n_main_streams; i++) {
if (v->main_streams[i]->discard < AVDISCARD_ALL) {
@@ -1270,7 +1370,7 @@ restart:
}
/* If this is a live stream and the reload interval has elapsed since
- * the last playlist reload, reload the playlists now. */
+ * the last playlist reload, reload the playlists now. */
reload_interval = default_reload_interval(v);
reload:
@@ -1293,7 +1393,7 @@ reload:
v->cur_seq_no = v->start_seq_no;
}
if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
- if (v->finished)
+ if (v->finished || v->is_subtitle)
return AVERROR_EOF;
while (av_gettime_relative() - v->last_load_time < reload_interval) {
if (ff_check_interrupt(c->interrupt_callback))
@@ -1304,48 +1404,26 @@ reload:
goto reload;
}
- seg = current_segment(v);
-
- /* load/update Media Initialization Section, if any */
- ret = update_init_section(v, seg);
- if (ret)
- return ret;
-
- ret = open_input(c, v, seg);
- if (ret < 0) {
- if (ff_check_interrupt(c->interrupt_callback))
- return AVERROR_EXIT;
- av_log(v->parent, AV_LOG_WARNING, "Failed to open segment of playlist %d\n",
- v->index);
- v->cur_seq_no += 1;
- goto reload;
+ if (!v->ctx && v->is_subtitle) {
+ ret = init_subtitle_context(v);
+ if (ret < 0)
+ return ret;
}
- just_opened = 1;
}
- if (v->init_sec_buf_read_offset < v->init_sec_data_len) {
- /* Push init section out first before first actual segment */
- int copy_size = FFMIN(v->init_sec_data_len - v->init_sec_buf_read_offset, buf_size);
- memcpy(buf, v->init_sec_buf, copy_size);
- v->init_sec_buf_read_offset += copy_size;
- return copy_size;
- }
-
- ret = read_from_url(v, current_segment(v), buf, buf_size, READ_NORMAL);
- if (ret > 0) {
- if (just_opened && v->is_id3_timestamped != 0) {
- /* Intercept ID3 tags here, elementary audio streams are required
- * to convey timestamps using them in the beginning of each segment. */
- intercept_id3(v, buf, buf_size, &ret);
- }
-
+ /* EOF flag may get set when the end of a segment is reached */
+ v->pb.eof_reached = 0;
+ ret = av_read_frame(v->ctx, &v->pkt);
+ if (!ret) {
return ret;
}
ff_format_io_close(v->parent, &v->input);
v->cur_seq_no++;
-
c->cur_seq_no = v->cur_seq_no;
+ if (v->is_subtitle)
+ avformat_close_input(&v->ctx);
+
goto restart;
}
@@ -1492,16 +1570,6 @@ static int save_avio_options(AVFormatContext *s)
return ret;
}
-static int nested_io_open(AVFormatContext *s, AVIOContext **pb, const char *url,
- int flags, AVDictionary **opts)
-{
- av_log(s, AV_LOG_ERROR,
- "A HLS playlist item '%s' referred to an external file '%s'. "
- "Opening this file was forbidden for security reasons\n",
- s->filename, url);
- return AVERROR(EPERM);
-}
-
static void add_stream_to_programs(AVFormatContext *s, struct playlist *pls, AVStream *stream)
{
HLSContext *c = s->priv_data;
@@ -1602,6 +1670,7 @@ static int hls_close(AVFormatContext *s)
free_rendition_list(c);
av_dict_free(&c->avio_opts);
+ av_dict_free(&c->demuxer_opts);
return 0;
}
@@ -1708,10 +1777,13 @@ static int hls_read_header(AVFormatContext *s)
highest_cur_seq_no = FFMAX(highest_cur_seq_no, pls->cur_seq_no);
}
+ av_dict_set(&c->demuxer_opts, "prefer_hls_mpegts_pts", "1", 0);
+
/* Open the demuxer for each playlist */
for (i = 0; i < c->n_playlists; i++) {
struct playlist *pls = c->playlists[i];
AVInputFormat *in_fmt = NULL;
+ AVDictionary *opts = NULL;
if (!(pls->ctx = avformat_alloc_context())) {
ret = AVERROR(ENOMEM);
@@ -1765,7 +1837,9 @@ static int hls_read_header(AVFormatContext *s)
if ((ret = ff_copy_whiteblacklists(pls->ctx, s)) < 0)
goto fail;
- ret = avformat_open_input(&pls->ctx, pls->segments[0]->url, in_fmt, NULL);
+ av_dict_copy(&opts, c->demuxer_opts, 0);
+ ret = avformat_open_input(&pls->ctx, pls->segments[0]->url, in_fmt, &opts);
+ av_dict_free(&opts);
if (ret < 0)
goto fail;
@@ -1843,6 +1917,8 @@ static int recheck_discard_flags(AVFormatContext *s, int first)
} else if (first && !pls->cur_needed && pls->needed) {
if (pls->input)
ff_format_io_close(pls->parent, &pls->input);
+ if (pls->is_subtitle)
+ avformat_close_input(&pls->ctx);
pls->needed = 0;
changed = 1;
av_log(s, AV_LOG_INFO, "No longer receiving playlist %d\n", i);
@@ -1909,7 +1985,7 @@ static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
while (1) {
int64_t ts_diff;
AVRational tb;
- ret = av_read_frame(pls->ctx, &pls->pkt);
+ ret = read_packet(pls, &pls->pkt);
if (ret < 0) {
if (!avio_feof(&pls->pb) && ret != AVERROR_EOF)
return ret;
@@ -2085,7 +2161,11 @@ static int hls_read_seek(AVFormatContext *s, int stream_index,
/* Reset the pos, to let the mpegts demuxer know we've seeked. */
pls->pb.pos = 0;
/* Flush the packet queue of the subdemuxer. */
- ff_read_frame_flush(pls->ctx);
+ if (pls->ctx)
+ ff_read_frame_flush(pls->ctx);
+
+ if (pls->is_subtitle)
+ avformat_close_input(&pls->ctx);
pls->seek_timestamp = seek_timestamp;
pls->seek_flags = flags;
--
2.1.4
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