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rtph264depay: expose wait-for-keyframe property

Browse source 
Similar to rtpvp8depay, when packet loss occurs, the depayloader
starts waiting for a keyframe.

We try to only stop waiting when all the packets for the new keyframe
have been received, by only resetting waiting_for_keyframe when
encountering the first packet of a keyframe, this is slightly
fragile because there is no bit that explicitly marks the start
of an access unit, so we rely on the existing picture_start
detection code.

As a consequence, the property is only meaningful when outputting
access units, and is ignored when outputting NALs directly.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/834>
This commit is contained in:
Mathieu Duponchelle 2020-12-09 01:24:57 +01:00 committed by GStreamer Merge Bot
parent e71648e214
commit 69a43dd00b
2 changed files with 103 additions and 24 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

124
gst/rtp/gstrtph264depay.c
View file

@ -38,6 +38,14 @@ GST_DEBUG_CATEGORY_STATIC (rtph264depay_debug);
* expressed a restriction or preference via caps */
#define DEFAULT_BYTE_STREAM TRUE
#define DEFAULT_ACCESS_UNIT FALSE
#define DEFAULT_WAIT_FOR_KEYFRAME FALSE
enum
{
PROP_0,
PROP_WAIT_FOR_KEYFRAME
};
/* 3 zero bytes syncword */
static const guint8 sync_bytes[] = { 0, 0, 0, 1 };
@ -99,6 +107,38 @@ static void gst_rtp_h264_depay_push (GstRtpH264Depay * rtph264depay,
GstBuffer * outbuf, gboolean keyframe, GstClockTime timestamp,
gboolean marker);
static void
gst_rtp_h264_depay_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstRtpH264Depay *self = GST_RTP_H264_DEPAY (object);
switch (prop_id) {
case PROP_WAIT_FOR_KEYFRAME:
self->wait_for_keyframe = g_value_get_boolean (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rtp_h264_depay_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec)
{
GstRtpH264Depay *self = GST_RTP_H264_DEPAY (object);
switch (prop_id) {
case PROP_WAIT_FOR_KEYFRAME:
g_value_set_boolean (value, self->wait_for_keyframe);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rtp_h264_depay_class_init (GstRtpH264DepayClass * klass)
{
@ -111,6 +151,23 @@ gst_rtp_h264_depay_class_init (GstRtpH264DepayClass * klass)
gstrtpbasedepayload_class = (GstRTPBaseDepayloadClass *) klass;
gobject_class->finalize = gst_rtp_h264_depay_finalize;
gobject_class->set_property = gst_rtp_h264_depay_set_property;
gobject_class->get_property = gst_rtp_h264_depay_get_property;
/**
* GstRtpH264Depay:wait-for-keyframe:
*
* Wait for the next keyframe after packet loss,
* meaningful only when outputting access units
*
* Since: 1.20
*/
g_object_class_install_property (gobject_class, PROP_WAIT_FOR_KEYFRAME,
g_param_spec_boolean ("wait-for-keyframe", "Wait for Keyframe",
"Wait for the next keyframe after packet loss, meaningful only when "
"outputting access units",
DEFAULT_WAIT_FOR_KEYFRAME,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
gst_element_class_add_static_pad_template (gstelement_class,
&gst_rtp_h264_depay_src_template);
@ -139,6 +196,7 @@ gst_rtp_h264_depay_init (GstRtpH264Depay * rtph264depay)
(GDestroyNotify) gst_buffer_unref);
rtph264depay->pps = g_ptr_array_new_with_free_func (
(GDestroyNotify) gst_buffer_unref);
rtph264depay->wait_for_keyframe = DEFAULT_WAIT_FOR_KEYFRAME;
}
static void
@ -146,6 +204,7 @@ gst_rtp_h264_depay_reset (GstRtpH264Depay * rtph264depay, gboolean hard)
{
gst_adapter_clear (rtph264depay->adapter);
rtph264depay->wait_start = TRUE;
rtph264depay->waiting_for_keyframe = rtph264depay->wait_for_keyframe;
gst_adapter_clear (rtph264depay->picture_adapter);
rtph264depay->picture_start = FALSE;
rtph264depay->last_keyframe = FALSE;
@ -952,31 +1011,31 @@ gst_rtp_h264_depay_handle_nal (GstRtpH264Depay * rtph264depay, GstBuffer * nal,
if (rtph264depay->merge) {
gboolean start = FALSE, complete = FALSE;
/* consider a coded slices (IDR or not) to start a picture,
* (so ending the previous one) if first_mb_in_slice == 0
* (non-0 is part of previous one) */
/* NOTE this is not entirely according to Access Unit specs in 7.4.1.2.4,
* but in practice it works in sane cases, needs not much parsing,
* and also works with broken frame_num in NAL (where spec-wise would fail) */
/* FIXME: this code isn't correct for interlaced content as AUs should be
* constructed with pairs of fields and the guess here will just push out
* AUs with a single field in it */
if (nal_type == 1 || nal_type == 2 || nal_type == 5) {
/* we have a picture start */
start = TRUE;
if (map.data[5] & 0x80) {
/* first_mb_in_slice == 0 completes a picture */
complete = TRUE;
}
} else if (nal_type >= 6 && nal_type <= 9) {
/* SEI, SPS, PPS, AU terminate picture */
complete = TRUE;
}
GST_DEBUG_OBJECT (depayload, "start %d, complete %d", start, complete);
/* marker bit isn't mandatory so in the following code we try to guess
* an AU boundary by detecting a new picture start */
if (!marker) {
/* consider a coded slices (IDR or not) to start a picture,
* (so ending the previous one) if first_mb_in_slice == 0
* (non-0 is part of previous one) */
/* NOTE this is not entirely according to Access Unit specs in 7.4.1.2.4,
* but in practice it works in sane cases, needs not much parsing,
* and also works with broken frame_num in NAL (where spec-wise would fail) */
/* FIXME: this code isn't correct for interlaced content as AUs should be
* constructed with pairs of fields and the guess here will just push out
* AUs with a single field in it */
if (nal_type == 1 || nal_type == 2 || nal_type == 5) {
/* we have a picture start */
start = TRUE;
if (map.data[5] & 0x80) {
/* first_mb_in_slice == 0 completes a picture */
complete = TRUE;
}
} else if (nal_type >= 6 && nal_type <= 9) {
/* SEI, SPS, PPS, AU terminate picture */
complete = TRUE;
}
GST_DEBUG_OBJECT (depayload, "start %d, complete %d", start, complete);
if (complete && rtph264depay->picture_start)
outbuf = gst_rtp_h264_complete_au (rtph264depay, &out_timestamp,
&out_keyframe);
@ -984,6 +1043,9 @@ gst_rtp_h264_depay_handle_nal (GstRtpH264Depay * rtph264depay, GstBuffer * nal,
/* add to adapter */
gst_buffer_unmap (nal, &map);
if (!rtph264depay->picture_start && start && out_keyframe)
rtph264depay->waiting_for_keyframe = FALSE;
GST_DEBUG_OBJECT (depayload, "adding NAL to picture adapter");
gst_adapter_push (rtph264depay->picture_adapter, nal);
rtph264depay->last_ts = in_timestamp;
@ -1001,8 +1063,15 @@ gst_rtp_h264_depay_handle_nal (GstRtpH264Depay * rtph264depay, GstBuffer * nal,
}
if (outbuf) {
gst_rtp_h264_depay_push (rtph264depay, outbuf, out_keyframe, out_timestamp,
marker);
if (!rtph264depay->waiting_for_keyframe) {
gst_rtp_h264_depay_push (rtph264depay, outbuf, out_keyframe,
out_timestamp, marker);
} else {
GST_LOG_OBJECT (depayload,
"Dropping %" GST_PTR_FORMAT ", we are waiting for a keyframe",
outbuf);
gst_buffer_unref (outbuf);
}
}
return;
@ -1056,12 +1125,19 @@ gst_rtp_h264_depay_process (GstRTPBaseDepayload * depayload, GstRTPBuffer * rtp)
rtph264depay = GST_RTP_H264_DEPAY (depayload);
if (!rtph264depay->merge)
rtph264depay->waiting_for_keyframe = FALSE;
/* flush remaining data on discont */
if (GST_BUFFER_IS_DISCONT (rtp->buffer)) {
gst_adapter_clear (rtph264depay->adapter);
rtph264depay->wait_start = TRUE;
rtph264depay->current_fu_type = 0;
rtph264depay->last_fu_seqnum = 0;
if (rtph264depay->merge && rtph264depay->wait_for_keyframe) {
rtph264depay->waiting_for_keyframe = TRUE;
}
}
{

3
gst/rtp/gstrtph264depay.h
View file

@ -71,6 +71,9 @@ struct _GstRtpH264Depay
/* downstream allocator */
GstAllocator *allocator;
GstAllocationParams params;
gboolean wait_for_keyframe;
gboolean waiting_for_keyframe;
};
struct _GstRtpH264DepayClass