diff options
author | Anssi Hannula <anssi.hannula@iki.fi> | 2014-04-05 15:47:26 +0400 |
---|---|---|
committer | Anssi Hannula <anssi.hannula@iki.fi> | 2014-04-06 18:55:03 +0400 |
commit | 01b184e68d86d6ecd8e7a54b977734d710a917ab (patch) | |
tree | ede65db516031427ee945c6b4f8f9ebe304dbc82 /libavformat/hls.c | |
parent | 1cb8d986b8d4c5c87332514d8ba483108fbbf949 (diff) |
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>
Diffstat (limited to 'libavformat/hls.c')
-rw-r--r-- | libavformat/hls.c | 316 |
1 files changed, 305 insertions, 11 deletions
diff --git a/libavformat/hls.c b/libavformat/hls.c index fe142557d0..dd683e40d9 100644 --- a/libavformat/hls.c +++ b/libavformat/hls.c @@ -27,6 +27,7 @@ */ #include "libavutil/avstring.h" +#include "libavutil/avassert.h" #include "libavutil/intreadwrite.h" #include "libavutil/mathematics.h" #include "libavutil/opt.h" @@ -36,12 +37,16 @@ #include "internal.h" #include "avio_internal.h" #include "url.h" +#include "id3v2.h" #define INITIAL_BUFFER_SIZE 32768 #define MAX_FIELD_LEN 64 #define MAX_CHARACTERISTICS_LEN 512 +#define MPEG_TIME_BASE 90000 +#define MPEG_TIME_BASE_Q (AVRational){1, MPEG_TIME_BASE} + /* * An apple http stream consists of a playlist with media segment files, * played sequentially. There may be several playlists with the same @@ -100,6 +105,18 @@ struct playlist { char key_url[MAX_URL_SIZE]; uint8_t key[16]; + /* ID3 timestamp handling (elementary audio streams have ID3 timestamps + * (and possibly other ID3 tags) in the beginning of each segment) */ + int is_id3_timestamped; /* -1: not yet known */ + int64_t id3_mpegts_timestamp; /* in mpegts tb */ + int64_t id3_offset; /* in stream original tb */ + uint8_t* id3_buf; /* temp buffer for id3 parsing */ + unsigned int id3_buf_size; + AVDictionary *id3_initial; /* data from first id3 tag */ + int id3_found; /* ID3 tag found at some point */ + int id3_changed; /* ID3 tag data has changed at some point */ + ID3v2ExtraMeta *id3_deferred_extra; /* stored here until subdemuxer is opened */ + /* Renditions associated with this playlist, if any. * Alternative rendition playlists have a single rendition associated * with them, and variant main Media Playlists may have @@ -179,6 +196,9 @@ static void free_playlist_list(HLSContext *c) struct playlist *pls = c->playlists[i]; free_segment_list(pls); av_freep(&pls->renditions); + av_freep(&pls->id3_buf); + av_dict_free(&pls->id3_initial); + ff_id3v2_free_extra_meta(&pls->id3_deferred_extra); av_free_packet(&pls->pkt); av_free(pls->pb.buffer); if (pls->input) @@ -234,6 +254,10 @@ static struct playlist *new_playlist(HLSContext *c, const char *url, return NULL; reset_packet(&pls->pkt); ff_make_absolute_url(pls->url, sizeof(pls->url), base, url); + + pls->is_id3_timestamped = -1; + pls->id3_mpegts_timestamp = AV_NOPTS_VALUE; + dynarray_add(&c->playlists, &c->n_playlists, pls); return pls; } @@ -600,8 +624,14 @@ fail: return ret; } +enum ReadFromURLMode { + READ_NORMAL, + READ_COMPLETE, +}; + /* read from URLContext, limiting read to current segment */ -static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size) +static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size, + enum ReadFromURLMode mode) { int ret; struct segment *seg = pls->segments[pls->cur_seq_no - pls->start_seq_no]; @@ -610,7 +640,10 @@ static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size) if (seg->size >= 0) buf_size = FFMIN(buf_size, seg->size - pls->cur_seg_offset); - ret = ffurl_read(pls->input, buf, buf_size); + if (mode == READ_COMPLETE) + ret = ffurl_read_complete(pls->input, buf, buf_size); + else + ret = ffurl_read(pls->input, buf, buf_size); if (ret > 0) pls->cur_seg_offset += ret; @@ -618,6 +651,204 @@ static int read_from_url(struct playlist *pls, uint8_t *buf, int buf_size) return ret; } +/* Parse the raw ID3 data and pass contents to caller */ +static void parse_id3(AVFormatContext *s, AVIOContext *pb, + AVDictionary **metadata, int64_t *dts, + ID3v2ExtraMetaAPIC **apic, ID3v2ExtraMeta **extra_meta) +{ + static const char id3_priv_owner_ts[] = "com.apple.streaming.transportStreamTimestamp"; + ID3v2ExtraMeta *meta; + + ff_id3v2_read_dict(pb, metadata, ID3v2_DEFAULT_MAGIC, extra_meta); + for (meta = *extra_meta; meta; meta = meta->next) { + if (!strcmp(meta->tag, "PRIV")) { + ID3v2ExtraMetaPRIV *priv = meta->data; + if (priv->datasize == 8 && !strcmp(priv->owner, id3_priv_owner_ts)) { + /* 33-bit MPEG timestamp */ + int64_t ts = AV_RB64(priv->data); + av_log(s, AV_LOG_DEBUG, "HLS ID3 audio timestamp %"PRId64"\n", ts); + if ((ts & ~((1ULL << 33) - 1)) == 0) + *dts = ts; + else + av_log(s, AV_LOG_ERROR, "Invalid HLS ID3 audio timestamp %"PRId64"\n", ts); + } + } else if (!strcmp(meta->tag, "APIC") && apic) + *apic = meta->data; + } +} + +/* Check if the ID3 metadata contents have changed */ +static int id3_has_changed_values(struct playlist *pls, AVDictionary *metadata, + ID3v2ExtraMetaAPIC *apic) +{ + AVDictionaryEntry *entry = NULL; + AVDictionaryEntry *oldentry; + /* check that no keys have changed values */ + while ((entry = av_dict_get(metadata, "", entry, AV_DICT_IGNORE_SUFFIX))) { + oldentry = av_dict_get(pls->id3_initial, entry->key, NULL, AV_DICT_MATCH_CASE); + if (!oldentry || strcmp(oldentry->value, entry->value) != 0) + return 1; + } + + /* check if apic appeared */ + if (apic && (pls->ctx->nb_streams != 2 || !pls->ctx->streams[1]->attached_pic.data)) + return 1; + + if (apic) { + int size = pls->ctx->streams[1]->attached_pic.size; + if (size != apic->buf->size - FF_INPUT_BUFFER_PADDING_SIZE) + return 1; + + if (memcmp(apic->buf->data, pls->ctx->streams[1]->attached_pic.data, size) != 0) + return 1; + } + + return 0; +} + +/* Parse ID3 data and handle the found data */ +static void handle_id3(AVIOContext *pb, struct playlist *pls) +{ + AVDictionary *metadata = NULL; + ID3v2ExtraMetaAPIC *apic = NULL; + ID3v2ExtraMeta *extra_meta = NULL; + int64_t timestamp = AV_NOPTS_VALUE; + + parse_id3(pls->ctx, pb, &metadata, ×tamp, &apic, &extra_meta); + + if (timestamp != AV_NOPTS_VALUE) { + pls->id3_mpegts_timestamp = timestamp; + pls->id3_offset = 0; + } + + if (!pls->id3_found) { + /* initial ID3 tags */ + av_assert0(!pls->id3_deferred_extra); + pls->id3_found = 1; + + /* get picture attachment and set text metadata */ + if (pls->ctx->nb_streams) + ff_id3v2_parse_apic(pls->ctx, &extra_meta); + else + /* demuxer not yet opened, defer picture attachment */ + pls->id3_deferred_extra = extra_meta; + + av_dict_copy(&pls->ctx->metadata, metadata, 0); + pls->id3_initial = metadata; + + } else { + if (!pls->id3_changed && id3_has_changed_values(pls, metadata, apic)) { + avpriv_report_missing_feature(pls->ctx, "Changing ID3 metadata in HLS audio elementary stream"); + pls->id3_changed = 1; + } + av_dict_free(&metadata); + } + + if (!pls->id3_deferred_extra) + ff_id3v2_free_extra_meta(&extra_meta); +} + +/* Intercept and handle ID3 tags between URLContext and AVIOContext */ +static void intercept_id3(struct playlist *pls, uint8_t *buf, + int buf_size, int *len) +{ + /* intercept id3 tags, we do not want to pass them to the raw + * demuxer on all segment switches */ + int bytes; + int id3_buf_pos = 0; + int fill_buf = 0; + + /* gather all the id3 tags */ + while (1) { + /* see if we can retrieve enough data for ID3 header */ + if (*len < ID3v2_HEADER_SIZE && buf_size >= ID3v2_HEADER_SIZE) { + bytes = read_from_url(pls, buf + *len, ID3v2_HEADER_SIZE - *len, READ_COMPLETE); + if (bytes > 0) { + + if (bytes == ID3v2_HEADER_SIZE - *len) + /* no EOF yet, so fill the caller buffer again after + * we have stripped the ID3 tags */ + fill_buf = 1; + + *len += bytes; + + } else if (*len <= 0) { + /* error/EOF */ + *len = bytes; + fill_buf = 0; + } + } + + if (*len < ID3v2_HEADER_SIZE) + break; + + if (ff_id3v2_match(buf, ID3v2_DEFAULT_MAGIC)) { + struct segment *seg = pls->segments[pls->cur_seq_no - pls->start_seq_no]; + int64_t segsize = seg->size >= 0 ? seg->size : ffurl_size(pls->input); + int taglen = ff_id3v2_tag_len(buf); + int tag_got_bytes = FFMIN(taglen, *len); + int remaining = taglen - tag_got_bytes; + + if (taglen > segsize) { + av_log(pls->ctx, AV_LOG_ERROR, "Too large HLS ID3 tag (%d vs %"PRId64")\n", + taglen, segsize); + break; + } + + /* + * Copy the id3 tag to our temporary id3 buffer. + * We could read a small id3 tag directly without memcpy, but + * we would still need to copy the large tags, and handling + * both of those cases together with the possibility for multiple + * tags would make the handling a bit complex. + */ + pls->id3_buf = av_fast_realloc(pls->id3_buf, &pls->id3_buf_size, id3_buf_pos + taglen); + if (!pls->id3_buf) + break; + memcpy(pls->id3_buf + id3_buf_pos, buf, tag_got_bytes); + id3_buf_pos += tag_got_bytes; + + /* strip the intercepted bytes */ + *len -= tag_got_bytes; + memmove(buf, buf + tag_got_bytes, *len); + av_log(pls->ctx, AV_LOG_DEBUG, "Stripped %d HLS ID3 bytes\n", tag_got_bytes); + + if (remaining > 0) { + /* read the rest of the tag in */ + if (read_from_url(pls, pls->id3_buf + id3_buf_pos, remaining, READ_COMPLETE) != remaining) + break; + id3_buf_pos += remaining; + av_log(pls->ctx, AV_LOG_DEBUG, "Stripped additional %d HLS ID3 bytes\n", remaining); + } + + } else { + /* no more ID3 tags */ + break; + } + } + + /* re-fill buffer for the caller unless EOF */ + if (*len >= 0 && (fill_buf || *len == 0)) { + bytes = read_from_url(pls, buf + *len, buf_size - *len, READ_NORMAL); + + /* ignore error if we already had some data */ + if (bytes >= 0) + *len += bytes; + else if (*len == 0) + *len = bytes; + } + + if (pls->id3_buf) { + /* Now parse all the ID3 tags */ + AVIOContext id3ioctx; + ffio_init_context(&id3ioctx, pls->id3_buf, id3_buf_pos, 0, NULL, NULL, NULL, NULL); + handle_id3(&id3ioctx, pls); + } + + if (pls->is_id3_timestamped == -1) + pls->is_id3_timestamped = (pls->id3_mpegts_timestamp != AV_NOPTS_VALUE); +} + static int open_input(HLSContext *c, struct playlist *pls) { AVDictionary *opts = NULL; @@ -720,6 +951,7 @@ 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; if (!v->needed) return AVERROR_EOF; @@ -769,10 +1001,17 @@ reload: v->index); return ret; } + just_opened = 1; } - ret = read_from_url(v, buf, buf_size); + ret = read_from_url(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); + } + return ret; } ffurl_close(v->input); @@ -991,11 +1230,21 @@ static int hls_read_header(AVFormatContext *s) if (ret < 0) goto fail; + if (pls->id3_deferred_extra && pls->ctx->nb_streams == 1) { + ff_id3v2_parse_apic(pls->ctx, &pls->id3_deferred_extra); + avformat_queue_attached_pictures(pls->ctx); + ff_id3v2_free_extra_meta(&pls->id3_deferred_extra); + pls->id3_deferred_extra = NULL; + } + pls->ctx->ctx_flags &= ~AVFMTCTX_NOHEADER; ret = avformat_find_stream_info(pls->ctx, NULL); if (ret < 0) goto fail; + if (pls->is_id3_timestamped == -1) + av_log(s, AV_LOG_WARNING, "No expected HTTP requests have been made\n"); + /* Create new AVStreams for each stream in this playlist */ for (j = 0; j < pls->ctx->nb_streams; j++) { AVStream *st = avformat_new_stream(s, NULL); @@ -1005,8 +1254,13 @@ static int hls_read_header(AVFormatContext *s) goto fail; } st->id = i; - avpriv_set_pts_info(st, ist->pts_wrap_bits, ist->time_base.num, ist->time_base.den); + avcodec_copy_context(st->codec, pls->ctx->streams[j]->codec); + + if (pls->is_id3_timestamped) /* custom timestamps via id3 */ + avpriv_set_pts_info(st, 33, 1, MPEG_TIME_BASE); + else + avpriv_set_pts_info(st, ist->pts_wrap_bits, ist->time_base.num, ist->time_base.den); } add_metadata_from_renditions(s, pls, AVMEDIA_TYPE_AUDIO); @@ -1093,6 +1347,39 @@ static int recheck_discard_flags(AVFormatContext *s, int first) return changed; } +static void fill_timing_for_id3_timestamped_stream(struct playlist *pls) +{ + if (pls->id3_offset >= 0) { + pls->pkt.dts = pls->id3_mpegts_timestamp + + av_rescale_q(pls->id3_offset, + pls->ctx->streams[pls->pkt.stream_index]->time_base, + MPEG_TIME_BASE_Q); + if (pls->pkt.duration) + pls->id3_offset += pls->pkt.duration; + else + pls->id3_offset = -1; + } else { + /* there have been packets with unknown duration + * since the last id3 tag, should not normally happen */ + pls->pkt.dts = AV_NOPTS_VALUE; + } + + if (pls->pkt.duration) + pls->pkt.duration = av_rescale_q(pls->pkt.duration, + pls->ctx->streams[pls->pkt.stream_index]->time_base, + MPEG_TIME_BASE_Q); + + pls->pkt.pts = AV_NOPTS_VALUE; +} + +static AVRational get_timebase(struct playlist *pls) +{ + if (pls->is_id3_timestamped) + return MPEG_TIME_BASE_Q; + + return pls->ctx->streams[pls->pkt.stream_index]->time_base; +} + static int hls_read_packet(AVFormatContext *s, AVPacket *pkt) { HLSContext *c = s->priv_data; @@ -1112,7 +1399,7 @@ start: if (pls->needed && !pls->pkt.data) { while (1) { int64_t ts_diff; - AVStream *st; + AVRational tb; ret = av_read_frame(pls->ctx, &pls->pkt); if (ret < 0) { if (!url_feof(&pls->pb) && ret != AVERROR_EOF) @@ -1120,11 +1407,16 @@ start: reset_packet(&pls->pkt); break; } else { + /* 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; } } |