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hlsdemux: add more comments and document better all the threads involved
This commit is contained in:
Andoni Morales Alastruey
Sebastian Dröge
parent
8a683fc035
commit
3fa4b22149
1 changed files with 32 additions and 11 deletions
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@ -338,7 +338,7 @@ gst_hls_demux_sink_event (GstPad * pad, GstEvent * event)
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GST_BUFFER_SIZE (demux->playlist));
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gst_buffer_unref (demux->playlist);
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if (!gst_m3u8_client_update (demux->client, playlist)) {
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/* In most cases, this will happen when if we set a wrong url in the
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/* In most cases, this will happen if we set a wrong url in the
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* source element and we have received the 404 HTML response instead of
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* the playlist */
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GST_ELEMENT_ERROR (demux, STREAM, DECODE, ("Invalid playlist."), NULL);
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@ -407,14 +407,15 @@ gst_hls_demux_fetcher_chain (GstPad * pad, GstBuffer * buf)
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/* The source element can be an http source element. In case we get a 404,
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* the html response will be sent downstream and demux->downloaded_uri
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* will not be null, which might make us think that the request proceed
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* successfully. But it it will also post an error message in the bus that
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* successfully. But it will also post an error message in the bus that
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* is handled synchronously and that will set demux->fetcher_error to TRUE,
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* which is used to discard this buffer with the html response. */
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if (demux->fetcher_error) {
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goto done;
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}
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GST_LOG_OBJECT (demux, "Received new buffer in the fecther");
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GST_LOG_OBJECT (demux, "The uri fetcher received a new buffer of size %lld",
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GST_BUFFER_SIZE (buf));
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if (demux->downloaded_uri == NULL)
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demux->downloaded_uri = buf;
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else
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@ -431,22 +432,31 @@ gst_hls_demux_stop_fetcher (GstHLSDemux * demux, gboolean cancelled)
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{
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GstPad *pad;
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/* When the fetcher is stopped while it's downloading, we will get an EOS that
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* unblocks the fetcher thread and tries to stop it again from that thread.
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* Here we check if the fetcher as already been stopped before continuing */
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if (demux->fetcher == NULL || demux->stopping_fetcher)
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return;
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GST_DEBUG_OBJECT (demux, "Stopping fetcher.");
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demux->stopping_fetcher = TRUE;
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/* set the element state to NULL */
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gst_element_set_state (demux->fetcher, GST_STATE_NULL);
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/* unlink it from the internal pad */
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pad = gst_pad_get_peer (demux->fetcherpad);
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if (pad) {
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gst_pad_unlink (pad, demux->fetcherpad);
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gst_object_unref (pad);
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}
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/* and finally unref it */
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gst_object_unref (demux->fetcher);
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demux->fetcher = NULL;
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/* if we stopped it to cancell a download, free the cached buffer */
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if (cancelled && demux->downloaded_uri != NULL) {
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gst_buffer_unref (demux->downloaded_uri);
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demux->downloaded_uri = NULL;
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/* signal the fetcher thread that the download has finished/cancelled */
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g_cond_signal (demux->fetcher_cond);
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}
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}
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@ -466,13 +476,19 @@ gst_hls_demux_loop (GstHLSDemux * demux)
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GstBuffer *buf;
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GstFlowReturn ret;
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/* cache the first fragments if we need it */
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/* Loop for the source pad task. The task is started when we have
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* received the main playlist from the source element. It tries first to
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* cache the first fragments and then it waits until it has more data in the
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* queue. This task is woken up when we push a new fragment to the queue or
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* when we reached the end of the playlist */
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if (G_UNLIKELY (demux->need_cache)) {
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gboolean ret;
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ret = gst_hls_demux_cache_fragments (demux);
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if (!ret) {
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goto cache_error;
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}
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/* we can start now the updates thread */
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gst_hls_demux_start_update (demux);
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GST_INFO_OBJECT (demux, "First fragments cached successfully");
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}
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@ -602,6 +618,12 @@ gst_hls_demux_set_location (GstHLSDemux * demux, const gchar * uri)
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static gboolean
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gst_hls_demux_update_thread (GstHLSDemux * demux)
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{
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/* Loop for the updates. It's started when the first fragments are cached and
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* schedules the next update of the playlist (for lives sources) and the next
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* update of fragments. When a new fragment is downloaded, it compares the
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* download time with the next scheduled update to check if we can or should
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* switch to a different bitrate */
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g_mutex_lock (demux->thread_lock);
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while (TRUE) {
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/* block until the next scheduled update or the signal to quit this thread */
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@ -622,7 +644,7 @@ gst_hls_demux_update_thread (GstHLSDemux * demux)
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gst_hls_demux_schedule (demux);
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/* if it's a live source and the playlist couldn't be updated, there aren't
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* more fragments in the playlist so we just wait for the next schedulled
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* more fragments in the playlist, so we just wait for the next schedulled
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* update */
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if (gst_m3u8_client_is_live (demux->client) &&
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demux->client->update_failed_count > 0) {
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@ -655,8 +677,7 @@ gst_hls_demux_start_update (GstHLSDemux * demux)
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{
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GError *error;
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/* create a new thread for the updates so that we don't block in the streaming
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* thread */
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/* creates a new thread for the updates */
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demux->updates_thread = g_thread_create (
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(GThreadFunc) gst_hls_demux_update_thread, demux, TRUE, &error);
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return (error != NULL);
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@ -678,7 +699,7 @@ gst_hls_demux_cache_fragments (GstHLSDemux * demux)
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}
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}
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/* If this playlist is a list of playlists, select the first one
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/* If this playlist is a variant playlist, select the first one
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* and update it */
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if (gst_m3u8_client_has_variant_playlist (demux->client)) {
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GstM3U8 *child = demux->client->main->lists->data;
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@ -729,7 +750,7 @@ gst_hls_demux_fetch_location (GstHLSDemux * demux, const gchar * uri)
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if (ret == GST_STATE_CHANGE_FAILURE)
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goto state_change_error;
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/* wait until we have fetched the element */
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/* wait until we have fetched the uri */
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GST_DEBUG_OBJECT (demux, "Waiting to fetch the URI");
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g_cond_wait (demux->fetcher_cond, demux->fetcher_lock);
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@ -858,7 +879,7 @@ gst_hls_demux_switch_playlist (GstHLSDemux * demux)
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if (diff > limit) {
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gst_hls_demux_change_playlist (demux, TRUE);
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} else if (diff < 0) {
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/* if the client is to slow wait until it has accumulate a certain delay to
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/* if the client is too slow wait until it has accumulated a certain delay to
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* switch to a lower bitrate */
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demux->accumulated_delay -= diff;
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if (demux->accumulated_delay >= limit) {
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@ -891,7 +912,7 @@ gst_hls_demux_get_next_fragment (GstHLSDemux * demux, gboolean retry)
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return FALSE;
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if (discont) {
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GST_DEBUG_OBJECT (demux, "Marking fragment has discontinuous");
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GST_DEBUG_OBJECT (demux, "Marking fragment as discontinuous");
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GST_BUFFER_FLAG_SET (demux->downloaded_uri, GST_BUFFER_FLAG_DISCONT);
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}
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