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matroskademux: pull mode non-cue seeking
That is, in files that have no index (Cue), perform seek by scanning for nearest cluster with timecode before requested position. Scanning is done as a combination of interpolation and sequential scan. Fixes #617368.
This commit is contained in:
Mark Nauwelaerts
parent
4b76e95abe
commit
c626e90fda
2 changed files with 255 additions and 4 deletions
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@ -2315,11 +2315,232 @@ gst_matroska_demux_move_to_entry (GstMatroskaDemux * demux,
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return TRUE;
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}
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/* bisect and scan through file for cluster starting before @time,
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* returns fake index entry with corresponding info on cluster */
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static GstMatroskaIndex *
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gst_matroska_demux_search_pos (GstMatroskaDemux * demux, GstClockTime time)
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{
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GstMatroskaIndex *entry;
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GstMatroskaDemuxState current_state;
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GstClockTime otime, prev_cluster_time, current_cluster_time, cluster_time;
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gint64 opos, newpos, startpos = 0, current_offset;
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gint64 prev_cluster_offset, current_cluster_offset, cluster_offset;
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const guint chunk = 64 * 1024;
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GstBuffer *buf = NULL;
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GstFlowReturn ret;
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guint64 length;
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guint32 id;
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guint needed;
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/* (under)estimate new position, resync using cluster ebml id,
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* and scan forward to appropriate cluster
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* (and re-estimate if need to go backward) */
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prev_cluster_time = GST_CLOCK_TIME_NONE;
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/* store some current state */
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current_state = demux->state;
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g_return_val_if_fail (current_state == GST_MATROSKA_DEMUX_STATE_DATA, NULL);
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current_cluster_offset = demux->cluster_offset;
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current_cluster_time = demux->cluster_time;
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current_offset = demux->offset;
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demux->state = GST_MATROSKA_DEMUX_STATE_SCANNING;
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/* estimate using start and current position */
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opos = demux->offset - demux->ebml_segment_start;
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otime = demux->segment.last_stop;
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retry:
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GST_LOG_OBJECT (demux,
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"opos: %" G_GUINT64_FORMAT ", otime: %" GST_TIME_FORMAT, opos,
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GST_TIME_ARGS (otime));
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newpos = gst_util_uint64_scale (opos, time, otime) - chunk;
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if (newpos < 0)
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newpos = 0;
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/* favour undershoot */
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newpos = newpos * 90 / 100;
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newpos += demux->ebml_segment_start;
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GST_DEBUG_OBJECT (demux,
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"estimated offset for %" GST_TIME_FORMAT ": %" G_GINT64_FORMAT,
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GST_TIME_ARGS (time), newpos);
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/* and at least start scanning before previous scan start to avoid looping */
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startpos = startpos * 90 / 100;
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if (startpos && startpos < newpos)
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newpos = startpos;
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/* read in at newpos and scan for ebml cluster id */
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startpos = newpos;
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while (1) {
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GstByteReader reader;
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gint cluster_pos;
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ret = gst_pad_pull_range (demux->sinkpad, newpos, chunk, &buf);
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if (ret == GST_FLOW_UNEXPECTED) {
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/* heuristic HACK */
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newpos = startpos * 80 / 100;
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GST_DEBUG_OBJECT (demux, "EOS; "
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"new estimated offset for %" GST_TIME_FORMAT ": %" G_GINT64_FORMAT,
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GST_TIME_ARGS (time), newpos);
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startpos = newpos;
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continue;
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} else if (ret != GST_FLOW_OK) {
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goto exit;
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}
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GST_DEBUG_OBJECT (demux, "read buffer size %d at offset %" G_GINT64_FORMAT,
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GST_BUFFER_SIZE (buf), newpos);
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gst_byte_reader_init_from_buffer (&reader, buf);
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cluster_pos = 0;
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resume:
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cluster_pos = gst_byte_reader_masked_scan_uint32 (&reader, 0xffffffff,
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GST_MATROSKA_ID_CLUSTER, cluster_pos,
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GST_BUFFER_SIZE (buf) - cluster_pos);
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if (cluster_pos >= 0) {
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newpos += cluster_pos;
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GST_DEBUG_OBJECT (demux,
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"found cluster ebml id at offset %" G_GINT64_FORMAT, newpos);
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gst_buffer_unref (buf);
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buf = NULL;
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/* extra checks whether we really sync'ed to a cluster:
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* - either it is the first and only cluster
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* - either there is a cluster after this one
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* - either cluster length is undefined
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*/
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/* ok if first cluster (there may not a subsequent one) */
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if (newpos == demux->first_cluster_offset) {
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GST_DEBUG_OBJECT (demux, "cluster is first cluster -> OK");
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break;
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}
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demux->offset = newpos;
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ret =
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gst_matroska_demux_peek_id_length_pull (demux, &id, &length, &needed);
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if (ret != GST_FLOW_OK)
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goto resume;
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g_assert (id == GST_MATROSKA_ID_CLUSTER);
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GST_DEBUG_OBJECT (demux, "cluster size %" G_GUINT64_FORMAT ", prefix %d",
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length, needed);
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/* ok if undefined length or first cluster */
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if (length == G_MAXUINT64) {
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GST_DEBUG_OBJECT (demux, "cluster has undefined length -> OK");
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break;
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}
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/* skip cluster */
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demux->offset += length + needed;
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ret =
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gst_matroska_demux_peek_id_length_pull (demux, &id, &length, &needed);
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if (ret != GST_FLOW_OK)
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goto resume;
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GST_DEBUG_OBJECT (demux, "next element is %scluster",
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id == GST_MATROSKA_ID_CLUSTER ? "" : "not ");
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if (id == GST_MATROSKA_ID_CLUSTER)
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break;
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/* not ok, resume */
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goto resume;
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} else {
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/* partial cluster id may have been in tail of buffer */
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newpos += MAX (GST_BUFFER_SIZE (buf), 4) - 3;
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gst_buffer_unref (buf);
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buf = NULL;
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}
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}
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/* then start scanning and parsing for cluster time,
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* re-estimate if overshoot, otherwise next cluster and so on */
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demux->offset = newpos;
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demux->cluster_time = cluster_time = GST_CLOCK_TIME_NONE;
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while (1) {
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guint64 cluster_size;
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/* peek and parse some elements */
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ret = gst_matroska_demux_peek_id_length_pull (demux, &id, &length, &needed);
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if (ret != GST_FLOW_OK)
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goto error;
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GST_LOG_OBJECT (demux, "Offset %" G_GUINT64_FORMAT ", Element id 0x%x, "
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"size %" G_GUINT64_FORMAT ", needed %d", demux->offset, id,
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length, needed);
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ret = gst_matroska_demux_parse_id (demux, id, length, needed);
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if (ret != GST_FLOW_OK)
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goto error;
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if (id == GST_MATROSKA_ID_CLUSTER) {
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cluster_time = GST_CLOCK_TIME_NONE;
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if (length == G_MAXUINT64)
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cluster_size = 0;
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else
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cluster_size = length + needed;
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}
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if (demux->cluster_time != GST_CLOCK_TIME_NONE &&
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cluster_time == GST_CLOCK_TIME_NONE) {
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cluster_time = demux->cluster_time * demux->time_scale;
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cluster_offset = demux->cluster_offset;
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GST_DEBUG_OBJECT (demux, "found cluster at offset %" G_GINT64_FORMAT
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" with time %" GST_TIME_FORMAT, cluster_offset,
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GST_TIME_ARGS (cluster_time));
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if (cluster_time > time) {
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GST_DEBUG_OBJECT (demux, "overshot target");
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/* cluster overshoots */
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if (prev_cluster_time != GST_CLOCK_TIME_NONE) {
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/* prev cluster did not overshoot, so prev cluster is target */
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break;
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} else {
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/* re-estimate using this new position info */
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opos = cluster_offset;
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otime = cluster_time;
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goto retry;
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}
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} else {
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/* cluster undershoots, goto next one */
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prev_cluster_time = cluster_time;
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prev_cluster_offset = cluster_offset;
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/* skip cluster if length is defined,
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* otherwise will be skippingly parsed into */
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if (cluster_size) {
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GST_DEBUG_OBJECT (demux, "skipping to next cluster");
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demux->offset = cluster_offset + cluster_size;
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demux->cluster_time = GST_CLOCK_TIME_NONE;
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} else {
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GST_DEBUG_OBJECT (demux, "parsing/skipping cluster elements");
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}
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}
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}
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continue;
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error:
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if (ret == GST_FLOW_UNEXPECTED) {
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if (prev_cluster_time != GST_CLOCK_TIME_NONE)
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break;
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}
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goto exit;
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}
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entry = g_new0 (GstMatroskaIndex, 1);
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entry->time = prev_cluster_time;
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entry->pos = prev_cluster_offset - demux->ebml_segment_start;
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GST_DEBUG_OBJECT (demux, "simulated index entry; time %" GST_TIME_FORMAT
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", pos %" G_GUINT64_FORMAT, GST_TIME_ARGS (entry->time), entry->pos);
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exit:
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if (buf)
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gst_buffer_unref (buf);
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/* restore some state */
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demux->cluster_offset = current_cluster_offset;
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demux->cluster_time = current_cluster_time;
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demux->offset = current_offset;
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demux->state = current_state;
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return entry;
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}
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static gboolean
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gst_matroska_demux_handle_seek_event (GstMatroskaDemux * demux,
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GstPad * pad, GstEvent * event)
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{
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GstMatroskaIndex *entry = NULL;
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GstMatroskaIndex scan_entry;
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GstSeekFlags flags;
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GstSeekType cur_type, stop_type;
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GstFormat format;
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@ -2361,9 +2582,12 @@ gst_matroska_demux_handle_seek_event (GstMatroskaDemux * demux,
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if ((entry = gst_matroskademux_do_index_seek (demux, track,
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seeksegment.last_stop, &demux->seek_index, &demux->seek_entry)) ==
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NULL) {
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GST_DEBUG_OBJECT (demux, "No matching seek entry in index");
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GST_OBJECT_UNLOCK (demux);
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return FALSE;
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/* pull mode without index can scan later on */
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if (demux->index || demux->streaming) {
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GST_DEBUG_OBJECT (demux, "No matching seek entry in index");
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GST_OBJECT_UNLOCK (demux);
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return FALSE;
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}
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}
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GST_DEBUG_OBJECT (demux, "Seek position looks sane");
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GST_OBJECT_UNLOCK (demux);
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@ -2394,6 +2618,25 @@ gst_matroska_demux_handle_seek_event (GstMatroskaDemux * demux,
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GST_DEBUG_OBJECT (demux, "Waiting for streaming to stop");
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GST_PAD_STREAM_LOCK (demux->sinkpad);
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/* pull mode without index can do some scanning */
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if (!demux->streaming && !demux->index) {
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/* need to stop flushing upstream as we need it next */
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if (flush)
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gst_pad_push_event (demux->sinkpad, gst_event_new_flush_stop ());
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entry = gst_matroska_demux_search_pos (demux, seeksegment.last_stop);
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/* keep local copy */
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if (entry) {
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scan_entry = *entry;
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g_free (entry);
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entry = &scan_entry;
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} else {
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GST_DEBUG_OBJECT (demux, "Scan failed to find matching position");
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if (flush)
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gst_matroska_demux_send_event (demux, gst_event_new_flush_stop ());
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goto seek_error;
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}
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}
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if (keyunit) {
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GST_DEBUG_OBJECT (demux, "seek to key unit, adjusting segment start to %"
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GST_TIME_FORMAT, GST_TIME_ARGS (entry->time));
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@ -5346,6 +5589,11 @@ gst_matroska_demux_parse_id (GstMatroskaDemux * demux, guint32 id,
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break;
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}
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break;
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case GST_MATROSKA_DEMUX_STATE_SCANNING:
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if (id != GST_MATROSKA_ID_CLUSTER &&
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id != GST_MATROSKA_ID_CLUSTERTIMECODE)
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goto skip;
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/* fall-through */
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case GST_MATROSKA_DEMUX_STATE_HEADER:
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case GST_MATROSKA_DEMUX_STATE_DATA:
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case GST_MATROSKA_DEMUX_STATE_SEEK:
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@ -5379,6 +5627,7 @@ gst_matroska_demux_parse_id (GstMatroskaDemux * demux, guint32 id,
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}
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if (G_UNLIKELY (demux->state == GST_MATROSKA_DEMUX_STATE_HEADER)) {
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demux->state = GST_MATROSKA_DEMUX_STATE_DATA;
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demux->first_cluster_offset = demux->offset;
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GST_DEBUG_OBJECT (demux, "signaling no more pads");
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gst_element_no_more_pads (GST_ELEMENT (demux));
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/* send initial newsegment */
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@ -46,7 +46,8 @@ typedef enum {
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GST_MATROSKA_DEMUX_STATE_SEGMENT,
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GST_MATROSKA_DEMUX_STATE_HEADER,
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GST_MATROSKA_DEMUX_STATE_DATA,
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GST_MATROSKA_DEMUX_STATE_SEEK
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GST_MATROSKA_DEMUX_STATE_SEEK,
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GST_MATROSKA_DEMUX_STATE_SCANNING
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} GstMatroskaDemuxState;
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typedef struct _GstMatroskaDemux {
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@ -112,6 +113,7 @@ typedef struct _GstMatroskaDemux {
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/* some state saving */
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GstClockTime cluster_time;
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guint64 cluster_offset;
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guint64 first_cluster_offset;
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/* push based mode usual suspects */
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GstAdapter *adapter;
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