gstreamer/subprojects/gst-plugins-bad/gst/codectimestamper/gsth264timestamper.c

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/* GStreamer
* Copyright (C) 2022 Seungha Yang <seungha@centricular.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/**
* SECTION:element-h264timestamper
* @title: h264timestamper
* @short_description: A timestamp correction element for H.264 streams
*
* `h264timestamper` updates the DTS (Decoding Time Stamp) of each frame
* based on H.264 SPS codec setup data, specifically the frame reordering
* information written in the SPS indicating the maximum number of B-frames
* allowed.
*
* In order to determine the DTS of each frame, this element may need to hold
* back a few frames in case the codec data indicates that frame reordering is
* allowed for the given stream. That means this element may introduce additional
* latency for the DTS decision.
*
* This element can be useful if downstream elements require correct DTS
* information but upstream elements either do not provide it at all or the
* upstream DTS information is unreliable.
*
* For example, mp4 muxers typically require both DTS and PTS on the input
* buffers, but in case where the input H.264 data comes from Matroska files or
* RTP/RTSP streams DTS timestamps may be absent and this element may need to
* be used to clean up the DTS timestamps before handing it to the mp4 muxer.
*
* This is particularly the case where the H.264 stream contains B-frames
* (i.e. frame reordering is required), as streams without correct DTS information
* will confuse the muxer element and will result in unexpected (or bogus)
* duration/framerate/timestamp values in the muxed container stream.
*
* ## Example launch line
* ```
* gst-launch-1.0 filesrc location=video.mkv ! matroskademux ! h264parse ! h264timestamper ! mp4mux ! filesink location=output.mp4
* ```
*
* Since: 1.22
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/base/base.h>
#include <gst/codecparsers/gsth264parser.h>
#include "gsth264timestamper.h"
GST_DEBUG_CATEGORY_STATIC (gst_h264_timestamper_debug);
#define GST_CAT_DEFAULT gst_h264_timestamper_debug
static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/x-h264, alignment=(string) au"));
static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/x-h264, alignment=(string) au"));
struct _GstH264Timestamper
{
GstCodecTimestamper parent;
GstH264NalParser *parser;
gboolean packetized;
guint nal_length_size;
};
static gboolean gst_h264_timestamper_start (GstCodecTimestamper * timestamper);
static gboolean gst_h264_timestamper_stop (GstCodecTimestamper * timestamper);
static gboolean gst_h264_timestamper_set_caps (GstCodecTimestamper *
timestamper, GstCaps * caps);
static GstFlowReturn gst_h264_timestamper_handle_buffer (GstCodecTimestamper *
timestamper, GstBuffer * buffer);
static void gst_h264_timestamper_process_nal (GstH264Timestamper * self,
GstH264NalUnit * nalu);
G_DEFINE_TYPE (GstH264Timestamper,
gst_h264_timestamper, GST_TYPE_CODEC_TIMESTAMPER);
GST_ELEMENT_REGISTER_DEFINE (h264timestamper, "h264timestamper",
GST_RANK_MARGINAL, GST_TYPE_H264_TIMESTAMPER);
static void
gst_h264_timestamper_class_init (GstH264TimestamperClass * klass)
{
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
GstCodecTimestamperClass *timestamper_class =
GST_CODEC_TIMESTAMPER_CLASS (klass);
gst_element_class_add_static_pad_template (element_class, &sinktemplate);
gst_element_class_add_static_pad_template (element_class, &srctemplate);
gst_element_class_set_static_metadata (element_class, "H.264 timestamper",
"Codec/Video/Timestamper", "Timestamp H.264 streams",
"Seungha Yang <seungha@centricular.com>");
timestamper_class->start = GST_DEBUG_FUNCPTR (gst_h264_timestamper_start);
timestamper_class->stop = GST_DEBUG_FUNCPTR (gst_h264_timestamper_stop);
timestamper_class->set_caps =
GST_DEBUG_FUNCPTR (gst_h264_timestamper_set_caps);
timestamper_class->handle_buffer =
GST_DEBUG_FUNCPTR (gst_h264_timestamper_handle_buffer);
GST_DEBUG_CATEGORY_INIT (gst_h264_timestamper_debug, "h264timestamper", 0,
"h264timestamper");
}
static void
gst_h264_timestamper_init (GstH264Timestamper * self)
{
}
static gboolean
gst_h264_timestamper_set_caps (GstCodecTimestamper * timestamper,
GstCaps * caps)
{
GstH264Timestamper *self = GST_H264_TIMESTAMPER (timestamper);
GstStructure *s = gst_caps_get_structure (caps, 0);
const gchar *str;
gboolean found_format = FALSE;
const GValue *codec_data_val;
self->packetized = FALSE;
self->nal_length_size = 4;
str = gst_structure_get_string (s, "stream-format");
if (g_strcmp0 (str, "avc") == 0 || g_strcmp0 (str, "avc3") == 0) {
self->packetized = TRUE;
found_format = TRUE;
} else if (g_strcmp0 (str, "byte-stream") == 0) {
found_format = TRUE;
}
codec_data_val = gst_structure_get_value (s, "codec_data");
if (codec_data_val && GST_VALUE_HOLDS_BUFFER (codec_data_val)) {
GstBuffer *codec_data = gst_value_get_buffer (codec_data_val);
GstMapInfo map;
GstH264NalUnit *nalu;
GstH264ParserResult ret;
GstH264DecoderConfigRecord *config = NULL;
guint i;
if (!gst_buffer_map (codec_data, &map, GST_MAP_READ)) {
GST_ERROR_OBJECT (self, "Unable to map codec-data buffer");
return FALSE;
}
ret = gst_h264_parser_parse_decoder_config_record (self->parser,
map.data, map.size, &config);
if (ret != GST_H264_PARSER_OK) {
GST_WARNING_OBJECT (self, "Failed to parse codec-data");
goto unmap;
}
self->nal_length_size = config->length_size_minus_one + 1;
for (i = 0; i < config->sps->len; i++) {
nalu = &g_array_index (config->sps, GstH264NalUnit, i);
gst_h264_timestamper_process_nal (self, nalu);
}
for (i = 0; i < config->pps->len; i++) {
nalu = &g_array_index (config->pps, GstH264NalUnit, i);
gst_h264_timestamper_process_nal (self, nalu);
}
/* codec_data would mean packetized format */
if (!found_format)
self->packetized = TRUE;
unmap:
gst_buffer_unmap (codec_data, &map);
g_clear_pointer (&config, gst_h264_decoder_config_record_free);
}
return TRUE;
}
typedef struct
{
GstH264Level level;
guint32 max_mbps;
guint32 max_fs;
guint32 max_dpb_mbs;
guint32 max_main_br;
} LevelLimits;
static const LevelLimits level_limits_map[] = {
{GST_H264_LEVEL_L1, 1485, 99, 396, 64},
{GST_H264_LEVEL_L1B, 1485, 99, 396, 128},
{GST_H264_LEVEL_L1_1, 3000, 396, 900, 192},
{GST_H264_LEVEL_L1_2, 6000, 396, 2376, 384},
{GST_H264_LEVEL_L1_3, 11800, 396, 2376, 768},
{GST_H264_LEVEL_L2, 11880, 396, 2376, 2000},
{GST_H264_LEVEL_L2_1, 19800, 792, 4752, 4000},
{GST_H264_LEVEL_L2_2, 20250, 1620, 8100, 4000},
{GST_H264_LEVEL_L3, 40500, 1620, 8100, 10000},
{GST_H264_LEVEL_L3_1, 108000, 3600, 18000, 14000},
{GST_H264_LEVEL_L3_2, 216000, 5120, 20480, 20000},
{GST_H264_LEVEL_L4, 245760, 8192, 32768, 20000},
{GST_H264_LEVEL_L4_1, 245760, 8192, 32768, 50000},
{GST_H264_LEVEL_L4_2, 522240, 8704, 34816, 50000},
{GST_H264_LEVEL_L5, 589824, 22080, 110400, 135000},
{GST_H264_LEVEL_L5_1, 983040, 36864, 184320, 240000},
{GST_H264_LEVEL_L5_2, 2073600, 36864, 184320, 240000},
{GST_H264_LEVEL_L6, 4177920, 139264, 696320, 240000},
{GST_H264_LEVEL_L6_1, 8355840, 139264, 696320, 480000},
{GST_H264_LEVEL_L6_2, 16711680, 139264, 696320, 800000}
};
static guint
h264_level_to_max_dpb_mbs (GstH264Level level)
{
gint i;
for (i = 0; i < G_N_ELEMENTS (level_limits_map); i++) {
if (level == level_limits_map[i].level)
return level_limits_map[i].max_dpb_mbs;
}
return 0;
}
static void
gst_h264_timestamper_process_sps (GstH264Timestamper * self, GstH264SPS * sps)
{
guint8 level;
guint max_dpb_mbs;
guint width_mb, height_mb;
guint max_dpb_frames = 0;
guint max_reorder_frames = 0;
/* Spec A.3.1 and A.3.2
* For Baseline, Constrained Baseline and Main profile, the indicated level is
* Level 1b if level_idc is equal to 11 and constraint_set3_flag is equal to 1
*/
level = sps->level_idc;
if (level == 11 && (sps->profile_idc == 66 || sps->profile_idc == 77) &&
sps->constraint_set3_flag) {
/* Level 1b */
level = 9;
}
max_dpb_mbs = h264_level_to_max_dpb_mbs ((GstH264Level) level);
if (sps->vui_parameters_present_flag
&& sps->vui_parameters.bitstream_restriction_flag) {
max_dpb_frames = MAX (1, sps->vui_parameters.max_dec_frame_buffering);
} else if (max_dpb_mbs != 0) {
width_mb = sps->width / 16;
height_mb = sps->height / 16;
max_dpb_frames = MIN (max_dpb_mbs / (width_mb * height_mb), 16);
} else {
GST_WARNING_OBJECT (self, "Unable to get MAX DPB MBs");
max_dpb_frames = 16;
}
GST_DEBUG_OBJECT (self, "Max DPB size %d", max_dpb_frames);
max_reorder_frames = max_dpb_frames;
if (sps->vui_parameters_present_flag
&& sps->vui_parameters.bitstream_restriction_flag) {
max_reorder_frames = sps->vui_parameters.num_reorder_frames;
if (max_reorder_frames > max_dpb_frames) {
GST_WARNING_OBJECT (self, "num_reorder_frames %d > dpb size %d",
max_reorder_frames, max_dpb_frames);
max_reorder_frames = max_dpb_frames;
}
} else {
if (sps->profile_idc == 66 || sps->profile_idc == 83) {
/* baseline, constrained baseline and scalable-baseline profiles
only contain I/P frames. */
max_reorder_frames = 0;
} else if (sps->constraint_set3_flag) {
/* constraint_set3_flag may mean the -intra only profile. */
switch (sps->profile_idc) {
case 44:
case 86:
case 100:
case 110:
case 122:
case 244:
max_reorder_frames = 0;
break;
default:
break;
}
}
}
GST_DEBUG_OBJECT (self, "Max num reorder frames %d", max_reorder_frames);
gst_codec_timestamper_set_window_size (GST_CODEC_TIMESTAMPER_CAST (self),
max_reorder_frames);
}
static void
gst_h264_timestamper_process_nal (GstH264Timestamper * self,
GstH264NalUnit * nalu)
{
GstH264ParserResult ret;
switch (nalu->type) {
case GST_H264_NAL_SPS:{
GstH264SPS sps;
ret = gst_h264_parser_parse_sps (self->parser, nalu, &sps);
if (ret != GST_H264_PARSER_OK) {
GST_WARNING_OBJECT (self, "Failed to parse SPS");
break;
}
gst_h264_timestamper_process_sps (self, &sps);
gst_h264_sps_clear (&sps);
break;
}
/* TODO: parse PPS/SLICE and correct PTS based on POC if needed */
default:
break;
}
}
static GstFlowReturn
gst_h264_timestamper_handle_buffer (GstCodecTimestamper * timestamper,
GstBuffer * buffer)
{
GstH264Timestamper *self = GST_H264_TIMESTAMPER (timestamper);
GstMapInfo map;
/* Ignore any error while parsing NAL */
if (gst_buffer_map (buffer, &map, GST_MAP_READ)) {
GstH264ParserResult ret;
GstH264NalUnit nalu;
if (self->packetized) {
ret = gst_h264_parser_identify_nalu_avc (self->parser,
map.data, 0, map.size, self->nal_length_size, &nalu);
while (ret == GST_H264_PARSER_OK) {
gst_h264_timestamper_process_nal (self, &nalu);
ret = gst_h264_parser_identify_nalu_avc (self->parser,
map.data, nalu.offset + nalu.size, map.size, self->nal_length_size,
&nalu);
}
} else {
ret = gst_h264_parser_identify_nalu (self->parser,
map.data, 0, map.size, &nalu);
if (ret == GST_H264_PARSER_NO_NAL_END)
ret = GST_H264_PARSER_OK;
while (ret == GST_H264_PARSER_OK) {
gst_h264_timestamper_process_nal (self, &nalu);
ret = gst_h264_parser_identify_nalu (self->parser,
map.data, nalu.offset + nalu.size, map.size, &nalu);
if (ret == GST_H264_PARSER_NO_NAL_END)
ret = GST_H264_PARSER_OK;
}
}
gst_buffer_unmap (buffer, &map);
}
return GST_FLOW_OK;
}
static void
gst_h264_timestamper_reset (GstH264Timestamper * self)
{
g_clear_pointer (&self->parser, gst_h264_nal_parser_free);
}
static gboolean
gst_h264_timestamper_start (GstCodecTimestamper * timestamper)
{
GstH264Timestamper *self = GST_H264_TIMESTAMPER (timestamper);
gst_h264_timestamper_reset (self);
self->parser = gst_h264_nal_parser_new ();
return TRUE;
}
static gboolean
gst_h264_timestamper_stop (GstCodecTimestamper * timestamper)
{
GstH264Timestamper *self = GST_H264_TIMESTAMPER (timestamper);
gst_h264_timestamper_reset (self);
return TRUE;
}