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a45273aaeb
Add more description about those elements Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3021>
339 lines
10 KiB
C
339 lines
10 KiB
C
/* GStreamer
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* Copyright (C) 2022 Seungha Yang <seungha@centricular.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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/**
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* SECTION:element-h265timestamper
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* @title: h265timestamper
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* @short_description: A timestamp correction element for H.265 streams
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*
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* `h265timestamper` updates the DTS (Decoding Time Stamp) of each frame
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* based on H.265 SPS codec setup data, specifically the frame reordering
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* information written in the SPS indicating the maximum number of B-frames
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* allowed.
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*
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* In order to determine the DTS of each frame, this element may need to hold
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* back a few frames in case the codec data indicates that frame reordering is
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* allowed for the given stream. That means this element may introduce additional
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* latency for the DTS decision.
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*
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* This element can be useful if downstream elements require correct DTS
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* information but upstream elements either do not provide it at all or the
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* upstream DTS information is unreliable.
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*
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* For example, mp4 muxers typically require both DTS and PTS on the input
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* buffers, but in case where the input H.265 data comes from Matroska files or
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* RTP/RTSP streams DTS timestamps may be absent and this element may need to
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* be used to clean up the DTS timestamps before handing it to the mp4 muxer.
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*
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* This is particularly the case where the H.265 stream contains B-frames
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* (i.e. frame reordering is required), as streams without correct DTS information
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* will confuse the muxer element and will result in unexpected (or bogus)
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* duration/framerate/timestamp values in the muxed container stream.
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*
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* ## Example launch line
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* ```
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* gst-launch-1.0 filesrc location=video.mkv ! matroskademux ! h265parse ! h265timestamper ! mp4mux ! filesink location=output.mp4
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* ```
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*
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* Since: 1.22
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <gst/base/base.h>
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#include <gst/codecparsers/gsth265parser.h>
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#include "gsth265timestamper.h"
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GST_DEBUG_CATEGORY_STATIC (gst_h265_timestamper_debug);
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#define GST_CAT_DEFAULT gst_h265_timestamper_debug
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static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
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GST_PAD_SINK,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("video/x-h265, alignment=(string) au"));
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static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
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GST_PAD_SRC,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("video/x-h265, alignment=(string) au"));
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struct _GstH265Timestamper
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{
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GstCodecTimestamper parent;
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GstH265Parser *parser;
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gboolean packetized;
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guint nal_length_size;
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};
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static gboolean gst_h265_timestamper_start (GstCodecTimestamper * timestamper);
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static gboolean gst_h265_timestamper_stop (GstCodecTimestamper * timestamper);
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static gboolean gst_h265_timestamper_set_caps (GstCodecTimestamper *
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timestamper, GstCaps * caps);
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static GstFlowReturn gst_h265_timestamper_handle_buffer (GstCodecTimestamper *
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timestamper, GstBuffer * buffer);
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static void gst_h265_timestamper_process_nal (GstH265Timestamper * self,
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GstH265NalUnit * nalu);
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G_DEFINE_TYPE (GstH265Timestamper,
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gst_h265_timestamper, GST_TYPE_CODEC_TIMESTAMPER);
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GST_ELEMENT_REGISTER_DEFINE (h265timestamper, "h265timestamper",
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GST_RANK_NONE, GST_TYPE_H265_TIMESTAMPER);
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static void
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gst_h265_timestamper_class_init (GstH265TimestamperClass * klass)
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{
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GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
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GstCodecTimestamperClass *timestamper_class =
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GST_CODEC_TIMESTAMPER_CLASS (klass);
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gst_element_class_add_static_pad_template (element_class, &sinktemplate);
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gst_element_class_add_static_pad_template (element_class, &srctemplate);
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gst_element_class_set_static_metadata (element_class, "H.265 timestamper",
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"Codec/Video", "Timestamp H.265 streams",
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"Seungha Yang <seungha@centricular.com>");
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timestamper_class->start = GST_DEBUG_FUNCPTR (gst_h265_timestamper_start);
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timestamper_class->stop = GST_DEBUG_FUNCPTR (gst_h265_timestamper_stop);
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timestamper_class->set_caps =
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GST_DEBUG_FUNCPTR (gst_h265_timestamper_set_caps);
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timestamper_class->handle_buffer =
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GST_DEBUG_FUNCPTR (gst_h265_timestamper_handle_buffer);
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GST_DEBUG_CATEGORY_INIT (gst_h265_timestamper_debug, "h265timestamper", 0,
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"h265timestamper");
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}
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static void
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gst_h265_timestamper_init (GstH265Timestamper * self)
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{
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}
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static gboolean
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gst_h265_timestamper_set_caps (GstCodecTimestamper * timestamper,
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GstCaps * caps)
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{
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GstH265Timestamper *self = GST_H265_TIMESTAMPER (timestamper);
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GstStructure *s = gst_caps_get_structure (caps, 0);
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const gchar *str;
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gboolean found_format = FALSE;
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const GValue *codec_data_val;
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self->packetized = FALSE;
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self->nal_length_size = 4;
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str = gst_structure_get_string (s, "stream-format");
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if (g_strcmp0 (str, "hvc1") == 0 || g_strcmp0 (str, "hev1") == 0) {
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self->packetized = TRUE;
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found_format = TRUE;
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} else if (g_strcmp0 (str, "byte-stream") == 0) {
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found_format = TRUE;
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}
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codec_data_val = gst_structure_get_value (s, "codec_data");
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if (codec_data_val && GST_VALUE_HOLDS_BUFFER (codec_data_val)) {
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GstBuffer *codec_data = gst_value_get_buffer (codec_data_val);
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GstH265Parser *parser = self->parser;
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GstMapInfo map;
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GstH265NalUnit nalu;
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GstH265ParserResult pres;
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guint num_nal_arrays;
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guint off;
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guint num_nals, i, j;
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guint8 *data;
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gsize size;
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if (!gst_buffer_map (codec_data, &map, GST_MAP_READ)) {
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GST_ERROR_OBJECT (self, "Unable to map codec-data buffer");
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return FALSE;
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}
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data = map.data;
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size = map.size;
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/* parse the hvcC data */
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if (size < 23) {
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GST_WARNING_OBJECT (self, "hvcC too small");
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goto unmap;
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}
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/* wrong hvcC version */
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if (data[0] != 0 && data[0] != 1) {
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goto unmap;
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}
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self->nal_length_size = (data[21] & 0x03) + 1;
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GST_DEBUG_OBJECT (self, "nal length size %u", self->nal_length_size);
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num_nal_arrays = data[22];
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off = 23;
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for (i = 0; i < num_nal_arrays; i++) {
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if (off + 3 >= size) {
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GST_WARNING_OBJECT (self, "hvcC too small");
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goto unmap;
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}
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num_nals = GST_READ_UINT16_BE (data + off + 1);
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off += 3;
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for (j = 0; j < num_nals; j++) {
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pres = gst_h265_parser_identify_nalu_hevc (parser,
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data, off, size, 2, &nalu);
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if (pres != GST_H265_PARSER_OK) {
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GST_WARNING_OBJECT (self, "hvcC too small");
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goto unmap;
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}
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gst_h265_timestamper_process_nal (self, &nalu);
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off = nalu.offset + nalu.size;
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}
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}
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/* codec_data would mean packetized format */
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if (!found_format)
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self->packetized = TRUE;
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unmap:
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gst_buffer_unmap (codec_data, &map);
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}
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return TRUE;
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}
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static void
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gst_h265_timestamper_process_sps (GstH265Timestamper * self, GstH265SPS * sps)
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{
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guint max_reorder_frames =
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sps->max_num_reorder_pics[sps->max_sub_layers_minus1];
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GST_DEBUG_OBJECT (self, "Max num reorder frames %d", max_reorder_frames);
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gst_codec_timestamper_set_window_size (GST_CODEC_TIMESTAMPER_CAST (self),
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max_reorder_frames);
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}
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static void
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gst_h265_timestamper_process_nal (GstH265Timestamper * self,
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GstH265NalUnit * nalu)
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{
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GstH265ParserResult ret;
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switch (nalu->type) {
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case GST_H265_NAL_VPS:{
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GstH265VPS vps;
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ret = gst_h265_parser_parse_vps (self->parser, nalu, &vps);
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if (ret != GST_H265_PARSER_OK)
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GST_WARNING_OBJECT (self, "Failed to parse SPS");
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break;
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}
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case GST_H265_NAL_SPS:{
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GstH265SPS sps;
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ret = gst_h265_parser_parse_sps (self->parser, nalu, &sps, FALSE);
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if (ret != GST_H265_PARSER_OK) {
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GST_WARNING_OBJECT (self, "Failed to parse SPS");
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break;
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}
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gst_h265_timestamper_process_sps (self, &sps);
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break;
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}
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/* TODO: parse PPS/SLICE and correct PTS based on POC if needed */
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default:
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break;
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}
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}
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static GstFlowReturn
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gst_h265_timestamper_handle_buffer (GstCodecTimestamper * timestamper,
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GstBuffer * buffer)
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{
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GstH265Timestamper *self = GST_H265_TIMESTAMPER (timestamper);
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GstMapInfo map;
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/* Ignore any error while parsing NAL */
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if (gst_buffer_map (buffer, &map, GST_MAP_READ)) {
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GstH265ParserResult ret;
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GstH265NalUnit nalu;
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if (self->packetized) {
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ret = gst_h265_parser_identify_nalu_hevc (self->parser,
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map.data, 0, map.size, self->nal_length_size, &nalu);
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while (ret == GST_H265_PARSER_OK) {
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gst_h265_timestamper_process_nal (self, &nalu);
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ret = gst_h265_parser_identify_nalu_hevc (self->parser,
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map.data, nalu.offset + nalu.size, map.size, self->nal_length_size,
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&nalu);
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}
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} else {
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ret = gst_h265_parser_identify_nalu (self->parser,
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map.data, 0, map.size, &nalu);
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if (ret == GST_H265_PARSER_NO_NAL_END)
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ret = GST_H265_PARSER_OK;
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while (ret == GST_H265_PARSER_OK) {
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gst_h265_timestamper_process_nal (self, &nalu);
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ret = gst_h265_parser_identify_nalu (self->parser,
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map.data, nalu.offset + nalu.size, map.size, &nalu);
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if (ret == GST_H265_PARSER_NO_NAL_END)
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ret = GST_H265_PARSER_OK;
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}
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}
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gst_buffer_unmap (buffer, &map);
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}
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return GST_FLOW_OK;
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}
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static void
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gst_h265_timestamper_reset (GstH265Timestamper * self)
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{
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g_clear_pointer (&self->parser, gst_h265_parser_free);
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}
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static gboolean
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gst_h265_timestamper_start (GstCodecTimestamper * timestamper)
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{
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GstH265Timestamper *self = GST_H265_TIMESTAMPER (timestamper);
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gst_h265_timestamper_reset (self);
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self->parser = gst_h265_parser_new ();
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return TRUE;
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}
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static gboolean
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gst_h265_timestamper_stop (GstCodecTimestamper * timestamper)
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{
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GstH265Timestamper *self = GST_H265_TIMESTAMPER (timestamper);
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gst_h265_timestamper_reset (self);
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return TRUE;
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}
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