From 5386a426f39a94501c1cb73e61b24fe00221eef3 Mon Sep 17 00:00:00 2001 From: Seungha Yang Date: Fri, 8 Jul 2022 00:16:02 +0900 Subject: [PATCH] h265decoder: Report latency Similar to that of h264decoder Part-of: --- .../gst-libs/gst/codecs/gsth265decoder.c | 72 ++++++++++++++++++++++ 1 file changed, 72 insertions(+) diff --git a/subprojects/gst-plugins-bad/gst-libs/gst/codecs/gsth265decoder.c b/subprojects/gst-plugins-bad/gst-libs/gst/codecs/gsth265decoder.c index 84acda7..da55479 100644 --- a/subprojects/gst-plugins-bad/gst-libs/gst/codecs/gsth265decoder.c +++ b/subprojects/gst-plugins-bad/gst-libs/gst/codecs/gsth265decoder.c @@ -346,6 +346,77 @@ gst_h265_decoder_drain_output_queue (GstH265Decoder * self, guint num, } } +static void +gst_h265_decoder_set_latency (GstH265Decoder * self, const GstH265SPS * sps, + gint max_dpb_size) +{ + GstH265DecoderPrivate *priv = self->priv; + GstCaps *caps; + GstClockTime min, max; + GstStructure *structure; + gint fps_d = 1, fps_n = 0; + guint frames_delay; + + caps = gst_pad_get_current_caps (GST_VIDEO_DECODER_SRC_PAD (self)); + if (!caps) + return; + + structure = gst_caps_get_structure (caps, 0); + if (gst_structure_get_fraction (structure, "framerate", &fps_n, &fps_d)) { + if (fps_n == 0) { + /* variable framerate: see if we have a max-framerate */ + gst_structure_get_fraction (structure, "max-framerate", &fps_n, &fps_d); + } + } + gst_caps_unref (caps); + + /* if no fps or variable, then 25/1 */ + if (fps_n == 0) { + fps_n = 25; + fps_d = 1; + } + + /* Minimum possible latency could be calculated based on C.5.2.3 + * 1) # of pictures (marked as "needed for output") in DPB > sps_max_num_reorder_pics + * - We will assume all pictures in DPB are marked as "needed for output" + * 2) sps_max_latency_increase_plus1 != 0 and + * PicLatencyCount >= SpsMaxLatencyPictures + * - SpsMaxLatencyPictures is equal to + * "sps_max_num_reorder_pics + sps_max_latency_increase_plus1 - 1" + * and PicLatencyCount of each picture in DPB is increased by 1 per + * decoding loop. Note that PicLatencyCount of the currently decoded + * picture is zero. So, in case that all pictures in DPB are marked as + * "needed for output", Only condition 1) will have an effect + * regardless of sps_max_latency_increase_plus1. + * + * For example, assume sps_max_num_reorder_pics is 2 and + * sps_max_latency_increase_plus1 is 1, then SpsMaxLatencyPictures is 2. + * For a picture in DPB to have PicLatencyCount >= SpsMaxLatencyPictures, + * there must be at least 3 pictures including current picture in DPB + * (current picture's PicLatencyCount is zero). + * This is already covered by the condition 1). So, this condition 2) + * will have effect only when there are pictures marked as + * "not needed for output" in DPB. + * + * Thus, we can take sps_max_num_reorder_pics as a min latency value + */ + frames_delay = sps->max_num_reorder_pics[sps->max_sub_layers_minus1]; + + /* Consider output delay wanted by subclass */ + frames_delay += priv->preferred_output_delay; + + 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); + + GST_DEBUG_OBJECT (self, + "latency min %" GST_TIME_FORMAT " max %" GST_TIME_FORMAT + " min-frames-delay %d", GST_TIME_ARGS (min), GST_TIME_ARGS (max), + frames_delay); + + gst_video_decoder_set_latency (GST_VIDEO_DECODER (self), min, max); +} + static GstFlowReturn gst_h265_decoder_process_sps (GstH265Decoder * self, GstH265SPS * sps) { @@ -435,6 +506,7 @@ gst_h265_decoder_process_sps (GstH265Decoder * self, GstH265SPS * sps) priv->interlaced_source_flag = interlaced_source_flag; gst_h265_dpb_set_max_num_pics (priv->dpb, max_dpb_size); + gst_h265_decoder_set_latency (self, sps, max_dpb_size); } if (sps->max_latency_increase_plus1[sps->max_sub_layers_minus1]) { -- 2.7.4