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assrender: fix multiple subtitles on screen simultaneously

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This fixes an issue with SSA/ASS subtitles, where subtitles
would fail to appear if there was already a subtitle on screen.

This was because `struct _GstAssRender` had a single
`GstBuffer *subtitle_pending` member.  This meant that
the assrender context could only be aware of one subtitle
at a time.

This patch changes the subtitle_pending member to a
linked list of pending subtitles.

The `gst_ass_render_chain_text` function no longer needs
to care about whether there are already subtitles pending,
it simply appends new subtitles to the list.

The `gst_ass_render_chain_video` function has been modified
to handle the list of pending subtitles.

Finally, the `gst_ass_render_pop_text` function has been
modified to pop the entire list of pending subtitles.

https://bugzilla.gnome.org/show_bug.cgi?id=735944
This commit is contained in:
Michael Drake 2018-07-18 11:11:17 +01:00 committed by Jan Schmidt
parent b2d5c1ed3c
commit bba33533ab
2 changed files with 88 additions and 66 deletions
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110
ext/assrender/gstassrender.c
View file

@ -356,11 +356,13 @@ gst_ass_render_get_property (GObject * object, guint prop_id,
static void
gst_ass_render_pop_text (GstAssRender * render)
{
if (render->subtitle_pending) {
while (render->subtitle_pending) {
GST_DEBUG_OBJECT (render, "releasing text buffer %p",
render->subtitle_pending);
gst_buffer_unref (render->subtitle_pending);
render->subtitle_pending = NULL;
gst_buffer_unref (render->subtitle_pending->data);
render->subtitle_pending =
g_slist_remove_link (render->subtitle_pending,
render->subtitle_pending);
}
/* Let the text task know we used that buffer */
@ -1235,6 +1237,7 @@ wait_for_text_buf:
if (render->renderer_init_ok && render->track_init_ok && render->enable) {
/* Text pad linked, check if we have a text buffer queued */
if (render->subtitle_pending) {
GSList *subtitle_pending = render->subtitle_pending;
GstClockTime text_start = GST_CLOCK_TIME_NONE;
GstClockTime text_end = GST_CLOCK_TIME_NONE;
GstClockTime text_running_time = GST_CLOCK_TIME_NONE;
@ -1243,20 +1246,6 @@ wait_for_text_buf:
gdouble timestamp;
gint changed = 0;
/* if the text buffer isn't stamped right, pop it off the
* queue and display it for the current video frame only */
if (!GST_BUFFER_TIMESTAMP_IS_VALID (render->subtitle_pending) ||
!GST_BUFFER_DURATION_IS_VALID (render->subtitle_pending)) {
GST_WARNING_OBJECT (render,
"Got text buffer with invalid timestamp or duration");
gst_ass_render_pop_text (render);
GST_ASS_RENDER_UNLOCK (render);
goto wait_for_text_buf;
}
text_start = GST_BUFFER_TIMESTAMP (render->subtitle_pending);
text_end = text_start + GST_BUFFER_DURATION (render->subtitle_pending);
vid_running_time =
gst_segment_to_running_time (&render->video_segment, GST_FORMAT_TIME,
start);
@ -1264,6 +1253,26 @@ wait_for_text_buf:
gst_segment_to_running_time (&render->video_segment, GST_FORMAT_TIME,
stop);
while (subtitle_pending != NULL) {
/* if the text buffer isn't stamped right, pop it off the
* queue and display it for the current video frame only */
if (!GST_BUFFER_TIMESTAMP_IS_VALID (subtitle_pending->data) ||
!GST_BUFFER_DURATION_IS_VALID (subtitle_pending->data)) {
GSList *bad = subtitle_pending;
GST_WARNING_OBJECT (render,
"Got text buffer with invalid timestamp or duration");
gst_buffer_unref (bad->data);
subtitle_pending = bad->next;
render->subtitle_pending =
g_slist_remove_link (render->subtitle_pending, bad);
GST_ASS_RENDER_BROADCAST (render);
continue;
}
text_start = GST_BUFFER_TIMESTAMP (subtitle_pending->data);
text_end = text_start + GST_BUFFER_DURATION (subtitle_pending->data);
/* If timestamp and duration are valid */
text_running_time =
gst_segment_to_running_time (&render->video_segment,
@ -1281,16 +1290,26 @@ wait_for_text_buf:
/* Text too old */
if (text_running_time_end <= vid_running_time) {
GSList *old = subtitle_pending;
GST_DEBUG_OBJECT (render, "text buffer too old, popping");
gst_ass_render_pop_text (render);
GST_ASS_RENDER_UNLOCK (render);
goto wait_for_text_buf;
gst_buffer_unref (old->data);
subtitle_pending = old->next;
render->subtitle_pending =
g_slist_remove_link (render->subtitle_pending, old);
GST_ASS_RENDER_BROADCAST (render);
continue;
}
if (render->need_process) {
GST_DEBUG_OBJECT (render, "process text buffer");
gst_ass_render_process_text (render, render->subtitle_pending,
gst_ass_render_process_text (render, subtitle_pending->data,
text_running_time, text_running_time_end - text_running_time);
}
subtitle_pending = subtitle_pending->next;
}
if (render->need_process) {
render->need_process = FALSE;
}
@ -1320,10 +1339,33 @@ wait_for_text_buf:
/* Push the video frame */
ret = gst_ass_render_push_frame (render, buffer);
subtitle_pending = render->subtitle_pending;
while (subtitle_pending != NULL) {
text_start = GST_BUFFER_TIMESTAMP (subtitle_pending->data);
text_end = text_start + GST_BUFFER_DURATION (subtitle_pending->data);
text_running_time_end =
gst_segment_to_running_time (&render->video_segment,
GST_FORMAT_TIME, text_end);
if (text_running_time_end <= vid_running_time_end) {
GSList *old = subtitle_pending;
GST_DEBUG_OBJECT (render, "finished text buffer, popping");
GST_ASS_RENDER_LOCK (render);
gst_ass_render_pop_text (render);
gst_buffer_unref (old->data);
subtitle_pending = old->next;
render->subtitle_pending =
g_slist_remove_link (render->subtitle_pending, old);
GST_ASS_RENDER_BROADCAST (render);
GST_ASS_RENDER_UNLOCK (render);
render->need_process = TRUE;
if (g_slist_length (render->subtitle_pending) == 0) {
render->need_process = FALSE;
}
} else {
subtitle_pending = subtitle_pending->next;
}
}
} else {
gboolean wait_for_text_buf = TRUE;
@ -1465,34 +1507,14 @@ gst_ass_render_chain_text (GstPad * pad, GstObject * parent, GstBuffer * buffer)
else if (GST_BUFFER_DURATION_IS_VALID (buffer))
GST_BUFFER_DURATION (buffer) = clip_stop - clip_start;
if (render->subtitle_pending
&& (!GST_BUFFER_TIMESTAMP_IS_VALID (render->subtitle_pending)
|| !GST_BUFFER_DURATION_IS_VALID (render->subtitle_pending))) {
gst_buffer_unref (render->subtitle_pending);
render->subtitle_pending = NULL;
GST_ASS_RENDER_BROADCAST (render);
} else {
/* Wait for the previous buffer to go away */
while (render->subtitle_pending != NULL) {
GST_DEBUG ("Pad %s:%s has a buffer queued, waiting",
GST_DEBUG_PAD_NAME (pad));
GST_ASS_RENDER_WAIT (render);
GST_DEBUG ("Pad %s:%s resuming", GST_DEBUG_PAD_NAME (pad));
if (render->subtitle_flushing) {
GST_ASS_RENDER_UNLOCK (render);
ret = GST_FLOW_FLUSHING;
goto beach;
}
}
}
if (GST_BUFFER_TIMESTAMP_IS_VALID (buffer))
render->subtitle_segment.position = clip_start;
GST_DEBUG_OBJECT (render,
"New buffer arrived for timestamp %" GST_TIME_FORMAT,
GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buffer)));
render->subtitle_pending = gst_buffer_ref (buffer);
render->subtitle_pending = g_slist_append (render->subtitle_pending,
gst_buffer_ref (buffer));
render->need_process = TRUE;
/* in case the video chain is waiting for a text buffer, wake it up */

2
ext/assrender/gstassrender.h
View file

@ -67,7 +67,7 @@ struct _GstAssRender
GstVideoInfo info;
GstBuffer *subtitle_pending;
GSList *subtitle_pending;
gboolean subtitle_flushing;
gboolean subtitle_eos;
GstSegment subtitle_segment;