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codecs: h264dec: Calculate the latency by its bump mode.

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The current latency calculation just uses the num_reorder_frames,
which is not very precise. We should consider the bump mode of the
DPB, the faster it bumps, the lower latency we will have.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1046>
This commit is contained in:
He Junyan 2021-10-05 01:07:57 +08:00 committed by GStreamer Marge Bot
parent d0c5778669
commit 0345188aaa
1 changed files with 25 additions and 12 deletions
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37
subprojects/gst-plugins-bad/gst-libs/gst/codecs/gsth264decoder.c
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@ -1036,8 +1036,8 @@ gst_h264_decoder_init_current_picture (GstH264Decoder * self)
/* If the slice header indicates we will have to perform reference marking
* process after this picture is decoded, store required data for that
* purpose */
if (priv->current_slice.header.dec_ref_pic_marking.
adaptive_ref_pic_marking_mode_flag) {
if (priv->current_slice.header.
dec_ref_pic_marking.adaptive_ref_pic_marking_mode_flag) {
priv->current_picture->dec_ref_pic_marking =
priv->current_slice.header.dec_ref_pic_marking;
}
@ -2331,7 +2331,8 @@ gst_h264_decoder_set_latency (GstH264Decoder * self, const GstH264SPS * sps,
GstClockTime min, max;
GstStructure *structure;
gint fps_d = 1, fps_n = 0;
guint32 num_reorder_frames;
GstH264DpbBumpMode bump_level;
guint32 frames_delay;
caps = gst_pad_get_current_caps (GST_VIDEO_DECODER_SRC_PAD (self));
if (!caps)
@ -2352,18 +2353,30 @@ gst_h264_decoder_set_latency (GstH264Decoder * self, const GstH264SPS * sps,
fps_d = 1;
}
num_reorder_frames = priv->is_live ? 0 : 1;
if (sps->vui_parameters_present_flag
&& sps->vui_parameters.bitstream_restriction_flag)
num_reorder_frames = sps->vui_parameters.num_reorder_frames;
if (num_reorder_frames > max_dpb_size)
num_reorder_frames = priv->is_live ? 0 : 1;
bump_level = get_bump_level (self);
frames_delay = 0;
switch (bump_level) {
case GST_H264_DPB_BUMP_NORMAL_LATENCY:
/* We always wait the DPB full before bumping. */
frames_delay = max_dpb_size;
break;
case GST_H264_DPB_BUMP_LOW_LATENCY:
/* We bump the IDR if the second frame is not a minus POC. */
frames_delay = 1;
break;
case GST_H264_DPB_BUMP_VERY_LOW_LATENCY:
/* We bump the IDR immediately. */
frames_delay = 0;
break;
default:
g_assert_not_reached ();
break;
}
/* Consider output delay wanted by subclass */
num_reorder_frames += priv->preferred_output_delay;
frames_delay += priv->preferred_output_delay;
min = gst_util_uint64_scale_int (num_reorder_frames * GST_SECOND, fps_d,
fps_n);
min = gst_util_uint64_scale_int (frames_delay * GST_SECOND, fps_d, fps_n);
max = gst_util_uint64_scale_int ((max_dpb_size + priv->preferred_output_delay)
* GST_SECOND, fps_d, fps_n);