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https://git.ffmpeg.org/ffmpeg.git
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avformat/hls: parse ID3 timestamps for elementary audio streams
HLS provides MPEG TS timestamps via ID3 tags in the beginning of each segment of elementary audio streams. v2: fix issues with streams that have multiple ID3 tags Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
This commit is contained in:
Anssi Hannula
parent
1cb8d986b8
commit
01b184e68d
@ -27,6 +27,7 @@
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*/
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#include "libavutil/avstring.h"
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#include "libavutil/avassert.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/mathematics.h"
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#include "libavutil/opt.h"
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@ -36,12 +37,16 @@
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#include "internal.h"
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#include "avio_internal.h"
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#include "url.h"
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#include "id3v2.h"
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#define INITIAL_BUFFER_SIZE 32768
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#define MAX_FIELD_LEN 64
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#define MAX_CHARACTERISTICS_LEN 512
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#define MPEG_TIME_BASE 90000
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#define MPEG_TIME_BASE_Q (AVRational){1, MPEG_TIME_BASE}
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/*
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* An apple http stream consists of a playlist with media segment files,
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* played sequentially. There may be several playlists with the same
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@ -100,6 +105,18 @@ struct playlist {
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char key_url[MAX_URL_SIZE];
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uint8_t key[16];
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/* ID3 timestamp handling (elementary audio streams have ID3 timestamps
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* (and possibly other ID3 tags) in the beginning of each segment) */
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int is_id3_timestamped; /* -1: not yet known */
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int64_t id3_mpegts_timestamp; /* in mpegts tb */
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int64_t id3_offset; /* in stream original tb */
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uint8_t* id3_buf; /* temp buffer for id3 parsing */
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unsigned int id3_buf_size;
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AVDictionary *id3_initial; /* data from first id3 tag */
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int id3_found; /* ID3 tag found at some point */
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int id3_changed; /* ID3 tag data has changed at some point */
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ID3v2ExtraMeta *id3_deferred_extra; /* stored here until subdemuxer is opened */
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/* Renditions associated with this playlist, if any.
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* Alternative rendition playlists have a single rendition associated
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* with them, and variant main Media Playlists may have
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@ -179,6 +196,9 @@ static void free_playlist_list(HLSContext *c)
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struct playlist *pls = c->playlists[i];
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free_segment_list(pls);
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av_freep(&pls->renditions);
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av_freep(&pls->id3_buf);
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av_dict_free(&pls->id3_initial);
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ff_id3v2_free_extra_meta(&pls->id3_deferred_extra);
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av_free_packet(&pls->pkt);
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av_free(pls->pb.buffer);
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if (pls->input)
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@ -234,6 +254,10 @@ static struct playlist *new_playlist(HLSContext *c, const char *url,
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return NULL;
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reset_packet(&pls->pkt);
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ff_make_absolute_url(pls->url, sizeof(pls->url), base, url);
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pls->is_id3_timestamped = -1;
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pls->id3_mpegts_timestamp = AV_NOPTS_VALUE;
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dynarray_add(&c->playlists, &c->n_playlists, pls);
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return pls;
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}
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@ -600,8 +624,14 @@ fail:
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return ret;
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}
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enum ReadFromURLMode {
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READ_NORMAL,
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READ_COMPLETE,
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};
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/* read from URLContext, limiting read to current segment */
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static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size)
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static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size,
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enum ReadFromURLMode mode)
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{
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int ret;
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struct segment *seg = pls->segments[pls->cur_seq_no - pls->start_seq_no];
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@ -610,7 +640,10 @@ static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size)
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if (seg->size >= 0)
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buf_size = FFMIN(buf_size, seg->size - pls->cur_seg_offset);
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ret = ffurl_read(pls->input, buf, buf_size);
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if (mode == READ_COMPLETE)
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ret = ffurl_read_complete(pls->input, buf, buf_size);
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else
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ret = ffurl_read(pls->input, buf, buf_size);
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if (ret > 0)
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pls->cur_seg_offset += ret;
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@ -618,6 +651,204 @@ static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size)
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return ret;
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}
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/* Parse the raw ID3 data and pass contents to caller */
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static void parse_id3(AVFormatContext *s, AVIOContext *pb,
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AVDictionary **metadata, int64_t *dts,
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ID3v2ExtraMetaAPIC **apic, ID3v2ExtraMeta **extra_meta)
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{
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static const char id3_priv_owner_ts[] = "com.apple.streaming.transportStreamTimestamp";
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ID3v2ExtraMeta *meta;
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ff_id3v2_read_dict(pb, metadata, ID3v2_DEFAULT_MAGIC, extra_meta);
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for (meta = *extra_meta; meta; meta = meta->next) {
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if (!strcmp(meta->tag, "PRIV")) {
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ID3v2ExtraMetaPRIV *priv = meta->data;
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if (priv->datasize == 8 && !strcmp(priv->owner, id3_priv_owner_ts)) {
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/* 33-bit MPEG timestamp */
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int64_t ts = AV_RB64(priv->data);
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av_log(s, AV_LOG_DEBUG, "HLS ID3 audio timestamp %"PRId64"\n", ts);
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if ((ts & ~((1ULL << 33) - 1)) == 0)
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*dts = ts;
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else
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av_log(s, AV_LOG_ERROR, "Invalid HLS ID3 audio timestamp %"PRId64"\n", ts);
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}
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} else if (!strcmp(meta->tag, "APIC") && apic)
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*apic = meta->data;
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}
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}
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/* Check if the ID3 metadata contents have changed */
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static int id3_has_changed_values(struct playlist *pls, AVDictionary *metadata,
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ID3v2ExtraMetaAPIC *apic)
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{
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AVDictionaryEntry *entry = NULL;
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AVDictionaryEntry *oldentry;
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/* check that no keys have changed values */
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while ((entry = av_dict_get(metadata, "", entry, AV_DICT_IGNORE_SUFFIX))) {
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oldentry = av_dict_get(pls->id3_initial, entry->key, NULL, AV_DICT_MATCH_CASE);
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if (!oldentry || strcmp(oldentry->value, entry->value) != 0)
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return 1;
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}
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/* check if apic appeared */
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if (apic && (pls->ctx->nb_streams != 2 || !pls->ctx->streams[1]->attached_pic.data))
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return 1;
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if (apic) {
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int size = pls->ctx->streams[1]->attached_pic.size;
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if (size != apic->buf->size - FF_INPUT_BUFFER_PADDING_SIZE)
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return 1;
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if (memcmp(apic->buf->data, pls->ctx->streams[1]->attached_pic.data, size) != 0)
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return 1;
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}
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return 0;
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}
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/* Parse ID3 data and handle the found data */
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static void handle_id3(AVIOContext *pb, struct playlist *pls)
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{
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AVDictionary *metadata = NULL;
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ID3v2ExtraMetaAPIC *apic = NULL;
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ID3v2ExtraMeta *extra_meta = NULL;
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int64_t timestamp = AV_NOPTS_VALUE;
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parse_id3(pls->ctx, pb, &metadata, ×tamp, &apic, &extra_meta);
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if (timestamp != AV_NOPTS_VALUE) {
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pls->id3_mpegts_timestamp = timestamp;
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pls->id3_offset = 0;
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}
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if (!pls->id3_found) {
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/* initial ID3 tags */
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av_assert0(!pls->id3_deferred_extra);
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pls->id3_found = 1;
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/* get picture attachment and set text metadata */
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if (pls->ctx->nb_streams)
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ff_id3v2_parse_apic(pls->ctx, &extra_meta);
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else
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/* demuxer not yet opened, defer picture attachment */
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pls->id3_deferred_extra = extra_meta;
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av_dict_copy(&pls->ctx->metadata, metadata, 0);
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pls->id3_initial = metadata;
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} else {
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if (!pls->id3_changed && id3_has_changed_values(pls, metadata, apic)) {
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avpriv_report_missing_feature(pls->ctx, "Changing ID3 metadata in HLS audio elementary stream");
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pls->id3_changed = 1;
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}
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av_dict_free(&metadata);
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}
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if (!pls->id3_deferred_extra)
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ff_id3v2_free_extra_meta(&extra_meta);
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}
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/* Intercept and handle ID3 tags between URLContext and AVIOContext */
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static void intercept_id3(struct playlist *pls, uint8_t *buf,
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int buf_size, int *len)
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{
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/* intercept id3 tags, we do not want to pass them to the raw
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* demuxer on all segment switches */
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int bytes;
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int id3_buf_pos = 0;
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int fill_buf = 0;
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/* gather all the id3 tags */
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while (1) {
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/* see if we can retrieve enough data for ID3 header */
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if (*len < ID3v2_HEADER_SIZE && buf_size >= ID3v2_HEADER_SIZE) {
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bytes = read_from_url(pls, buf + *len, ID3v2_HEADER_SIZE - *len, READ_COMPLETE);
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if (bytes > 0) {
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if (bytes == ID3v2_HEADER_SIZE - *len)
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/* no EOF yet, so fill the caller buffer again after
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* we have stripped the ID3 tags */
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fill_buf = 1;
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*len += bytes;
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} else if (*len <= 0) {
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/* error/EOF */
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*len = bytes;
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fill_buf = 0;
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}
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}
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if (*len < ID3v2_HEADER_SIZE)
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break;
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if (ff_id3v2_match(buf, ID3v2_DEFAULT_MAGIC)) {
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struct segment *seg = pls->segments[pls->cur_seq_no - pls->start_seq_no];
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int64_t segsize = seg->size >= 0 ? seg->size : ffurl_size(pls->input);
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int taglen = ff_id3v2_tag_len(buf);
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int tag_got_bytes = FFMIN(taglen, *len);
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int remaining = taglen - tag_got_bytes;
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if (taglen > segsize) {
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av_log(pls->ctx, AV_LOG_ERROR, "Too large HLS ID3 tag (%d vs %"PRId64")\n",
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taglen, segsize);
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break;
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}
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/*
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* Copy the id3 tag to our temporary id3 buffer.
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* We could read a small id3 tag directly without memcpy, but
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* we would still need to copy the large tags, and handling
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* both of those cases together with the possibility for multiple
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* tags would make the handling a bit complex.
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*/
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pls->id3_buf = av_fast_realloc(pls->id3_buf, &pls->id3_buf_size, id3_buf_pos + taglen);
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if (!pls->id3_buf)
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break;
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memcpy(pls->id3_buf + id3_buf_pos, buf, tag_got_bytes);
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id3_buf_pos += tag_got_bytes;
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/* strip the intercepted bytes */
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*len -= tag_got_bytes;
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memmove(buf, buf + tag_got_bytes, *len);
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av_log(pls->ctx, AV_LOG_DEBUG, "Stripped %d HLS ID3 bytes\n", tag_got_bytes);
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if (remaining > 0) {
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/* read the rest of the tag in */
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if (read_from_url(pls, pls->id3_buf + id3_buf_pos, remaining, READ_COMPLETE) != remaining)
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break;
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id3_buf_pos += remaining;
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av_log(pls->ctx, AV_LOG_DEBUG, "Stripped additional %d HLS ID3 bytes\n", remaining);
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}
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} else {
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/* no more ID3 tags */
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break;
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}
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}
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/* re-fill buffer for the caller unless EOF */
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if (*len >= 0 && (fill_buf || *len == 0)) {
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bytes = read_from_url(pls, buf + *len, buf_size - *len, READ_NORMAL);
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/* ignore error if we already had some data */
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if (bytes >= 0)
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*len += bytes;
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else if (*len == 0)
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*len = bytes;
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}
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if (pls->id3_buf) {
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/* Now parse all the ID3 tags */
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AVIOContext id3ioctx;
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ffio_init_context(&id3ioctx, pls->id3_buf, id3_buf_pos, 0, NULL, NULL, NULL, NULL);
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handle_id3(&id3ioctx, pls);
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}
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if (pls->is_id3_timestamped == -1)
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pls->is_id3_timestamped = (pls->id3_mpegts_timestamp != AV_NOPTS_VALUE);
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}
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static int open_input(HLSContext *c, struct playlist *pls)
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{
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AVDictionary *opts = NULL;
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@ -720,6 +951,7 @@ static int read_data(void *opaque, uint8_t *buf, int buf_size)
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struct playlist *v = opaque;
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HLSContext *c = v->parent->priv_data;
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int ret, i;
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int just_opened = 0;
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if (!v->needed)
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return AVERROR_EOF;
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@ -769,10 +1001,17 @@ reload:
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v->index);
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return ret;
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}
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just_opened = 1;
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}
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ret = read_from_url(v, buf, buf_size);
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ret = read_from_url(v, buf, buf_size, READ_NORMAL);
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if (ret > 0) {
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if (just_opened && v->is_id3_timestamped != 0) {
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/* Intercept ID3 tags here, elementary audio streams are required
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* to convey timestamps using them in the beginning of each segment. */
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intercept_id3(v, buf, buf_size, &ret);
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}
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return ret;
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}
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ffurl_close(v->input);
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@ -991,11 +1230,21 @@ static int hls_read_header(AVFormatContext *s)
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if (ret < 0)
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goto fail;
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if (pls->id3_deferred_extra && pls->ctx->nb_streams == 1) {
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ff_id3v2_parse_apic(pls->ctx, &pls->id3_deferred_extra);
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avformat_queue_attached_pictures(pls->ctx);
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ff_id3v2_free_extra_meta(&pls->id3_deferred_extra);
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pls->id3_deferred_extra = NULL;
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}
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pls->ctx->ctx_flags &= ~AVFMTCTX_NOHEADER;
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ret = avformat_find_stream_info(pls->ctx, NULL);
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if (ret < 0)
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goto fail;
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if (pls->is_id3_timestamped == -1)
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av_log(s, AV_LOG_WARNING, "No expected HTTP requests have been made\n");
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/* Create new AVStreams for each stream in this playlist */
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for (j = 0; j < pls->ctx->nb_streams; j++) {
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AVStream *st = avformat_new_stream(s, NULL);
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@ -1005,8 +1254,13 @@ static int hls_read_header(AVFormatContext *s)
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goto fail;
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}
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st->id = i;
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avpriv_set_pts_info(st, ist->pts_wrap_bits, ist->time_base.num, ist->time_base.den);
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avcodec_copy_context(st->codec, pls->ctx->streams[j]->codec);
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if (pls->is_id3_timestamped) /* custom timestamps via id3 */
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avpriv_set_pts_info(st, 33, 1, MPEG_TIME_BASE);
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else
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avpriv_set_pts_info(st, ist->pts_wrap_bits, ist->time_base.num, ist->time_base.den);
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}
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add_metadata_from_renditions(s, pls, AVMEDIA_TYPE_AUDIO);
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@ -1093,6 +1347,39 @@ static int recheck_discard_flags(AVFormatContext *s, int first)
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return changed;
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}
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static void fill_timing_for_id3_timestamped_stream(struct playlist *pls)
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{
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if (pls->id3_offset >= 0) {
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pls->pkt.dts = pls->id3_mpegts_timestamp +
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av_rescale_q(pls->id3_offset,
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pls->ctx->streams[pls->pkt.stream_index]->time_base,
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MPEG_TIME_BASE_Q);
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if (pls->pkt.duration)
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pls->id3_offset += pls->pkt.duration;
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else
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pls->id3_offset = -1;
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} else {
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/* there have been packets with unknown duration
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* since the last id3 tag, should not normally happen */
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pls->pkt.dts = AV_NOPTS_VALUE;
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}
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if (pls->pkt.duration)
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pls->pkt.duration = av_rescale_q(pls->pkt.duration,
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pls->ctx->streams[pls->pkt.stream_index]->time_base,
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MPEG_TIME_BASE_Q);
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pls->pkt.pts = AV_NOPTS_VALUE;
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}
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static AVRational get_timebase(struct playlist *pls)
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{
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if (pls->is_id3_timestamped)
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return MPEG_TIME_BASE_Q;
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return pls->ctx->streams[pls->pkt.stream_index]->time_base;
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}
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static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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HLSContext *c = s->priv_data;
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@ -1112,7 +1399,7 @@ start:
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if (pls->needed && !pls->pkt.data) {
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while (1) {
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int64_t ts_diff;
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AVStream *st;
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AVRational tb;
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ret = av_read_frame(pls->ctx, &pls->pkt);
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if (ret < 0) {
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if (!url_feof(&pls->pb) && ret != AVERROR_EOF)
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@ -1120,11 +1407,16 @@ start:
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reset_packet(&pls->pkt);
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break;
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} else {
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/* stream_index check prevents matching picture attachments etc. */
|
||||
if (pls->is_id3_timestamped && pls->pkt.stream_index == 0) {
|
||||
/* audio elementary streams are id3 timestamped */
|
||||
fill_timing_for_id3_timestamped_stream(pls);
|
||||
}
|
||||
|
||||
if (c->first_timestamp == AV_NOPTS_VALUE &&
|
||||
pls->pkt.dts != AV_NOPTS_VALUE)
|
||||
c->first_timestamp = av_rescale_q(pls->pkt.dts,
|
||||
pls->ctx->streams[pls->pkt.stream_index]->time_base,
|
||||
AV_TIME_BASE_Q);
|
||||
get_timebase(pls), AV_TIME_BASE_Q);
|
||||
}
|
||||
|
||||
if (c->seek_timestamp == AV_NOPTS_VALUE)
|
||||
@ -1135,9 +1427,9 @@ start:
|
||||
break;
|
||||
}
|
||||
|
||||
st = pls->ctx->streams[pls->pkt.stream_index];
|
||||
tb = get_timebase(pls);
|
||||
ts_diff = av_rescale_rnd(pls->pkt.dts, AV_TIME_BASE,
|
||||
st->time_base.den, AV_ROUND_DOWN) -
|
||||
tb.den, AV_ROUND_DOWN) -
|
||||
c->seek_timestamp;
|
||||
if (ts_diff >= 0 && (c->seek_flags & AVSEEK_FLAG_ANY ||
|
||||
pls->pkt.flags & AV_PKT_FLAG_KEY)) {
|
||||
@ -1160,6 +1452,8 @@ start:
|
||||
int64_t mindts = minpls->pkt.dts;
|
||||
AVStream *st = pls->ctx->streams[pls->pkt.stream_index];
|
||||
AVStream *minst = minpls->ctx->streams[minpls->pkt.stream_index];
|
||||
AVRational tb = get_timebase( pls);
|
||||
AVRational mintb = get_timebase(minpls);
|
||||
|
||||
if (dts == AV_NOPTS_VALUE) {
|
||||
minplaylist = i;
|
||||
@ -1169,8 +1463,8 @@ start:
|
||||
if (minst->start_time != AV_NOPTS_VALUE)
|
||||
mindts -= minst->start_time;
|
||||
|
||||
if (av_compare_ts(dts, st->time_base,
|
||||
mindts, minst->time_base) < 0)
|
||||
if (av_compare_ts(dts, tb,
|
||||
mindts, mintb) < 0)
|
||||
minplaylist = i;
|
||||
}
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user