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Correctly set number of reference buffers in H264 encoder

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iNumRefFrame specifies total number of reference buffers to allocate.
For N temporal layers we need at least (N - 1) buffers to store last
encoded frames of all reference temporal layers.

There is no API in OpenH254 encoder to specify exact set of references
to be used to prediction of a given frame. Encoder can theoretically
use all available references.

Note that there is logic in OpenH264 which overrides iNumRefFrame to
max(iNumRefFrame, N - 1): https://source.chromium.org/chromium/chromium/src/+/main:third_party/openh264/src/codec/encoder/core/src/au_set.cpp;drc=8e90a2775c5b9448324fe8fef11d177cb65f36cc;l=122.
I.e., this change has no real effect. It only makes setup more clear.

Bug: none
Change-Id: If4b4970007e1cc55d8f052ea05213ab2e89a878f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/225480
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34445}
This commit is contained in:
Sergey Silkin
2021-07-09 13:45:29 +02:00
committed by WebRTC LUCI CQ
parent e91c992fa1
commit d6afbead2d
3 changed files with 17 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
modules/video_coding/codecs/h264/h264_encoder_impl.cc
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@ -16,6 +16,7 @@
#include "modules/video_coding/codecs/h264/h264_encoder_impl.h"
#include <algorithm>
#include <limits>
#include <string>
@ -241,7 +242,8 @@ int32_t H264EncoderImpl::InitEncode(const VideoCodec* inst,
configurations_[i].frame_dropping_on = codec_.H264()->frameDroppingOn;
configurations_[i].key_frame_interval = codec_.H264()->keyFrameInterval;
configurations_[i].num_temporal_layers =
codec_.simulcastStream[idx].numberOfTemporalLayers;
std::max(codec_.H264()->numberOfTemporalLayers,
codec_.simulcastStream[idx].numberOfTemporalLayers);
// Create downscaled image buffers.
if (i > 0) {
@ -578,7 +580,13 @@ SEncParamExt H264EncoderImpl::CreateEncoderParams(size_t i) const {
encoder_params.iMaxBitrate;
encoder_params.iTemporalLayerNum = configurations_[i].num_temporal_layers;
if (encoder_params.iTemporalLayerNum > 1) {
encoder_params.iNumRefFrame = 1;
// iNumRefFrame specifies total number of reference buffers to allocate.
// For N temporal layers we need at least (N - 1) buffers to store last
// encoded frames of all reference temporal layers.
// Note that there is no API in OpenH264 encoder to specify exact set of
// references to be used to prediction of a given frame. Encoder can
// theoretically use all available reference buffers.
encoder_params.iNumRefFrame = encoder_params.iTemporalLayerNum - 1;
}
RTC_LOG(INFO) << "OpenH264 version is " << OPENH264_MAJOR << "."
<< OPENH264_MINOR;

6
modules/video_coding/codecs/test/videocodec_test_fixture_impl.cc
View File

@ -128,6 +128,8 @@ std::string CodecSpecificToString(const VideoCodec& codec) {
case kVideoCodecH264:
ss << "frame_dropping: " << codec.H264().frameDroppingOn;
ss << "\nkey_frame_interval: " << codec.H264().keyFrameInterval;
ss << "\nnum_temporal_layers: "
<< static_cast<int>(codec.H264().numberOfTemporalLayers);
break;
default:
break;
@ -214,6 +216,8 @@ void VideoCodecTestFixtureImpl::Config::SetCodecSettings(
case kVideoCodecH264:
codec_settings.H264()->frameDroppingOn = frame_dropper_on;
codec_settings.H264()->keyFrameInterval = kBaseKeyFrameInterval;
codec_settings.H264()->numberOfTemporalLayers =
static_cast<uint8_t>(num_temporal_layers);
break;
default:
break;
@ -236,6 +240,8 @@ size_t VideoCodecTestFixtureImpl::Config::NumberOfTemporalLayers() const {
return codec_settings.VP8().numberOfTemporalLayers;
} else if (codec_settings.codecType == kVideoCodecVP9) {
return codec_settings.VP9().numberOfTemporalLayers;
} else if (codec_settings.codecType == kVideoCodecH264) {
return codec_settings.H264().numberOfTemporalLayers;
} else {
return 1;
}

1
modules/video_coding/utility/simulcast_test_fixture_impl.cc
View File

@ -590,6 +590,7 @@ void SimulcastTestFixtureImpl::SwitchingToOneStream(int width, int height) {
settings_.VP8()->numberOfTemporalLayers = 1;
temporal_layer_profile = kDefaultTemporalLayerProfile;
} else {
settings_.H264()->numberOfTemporalLayers = 1;
temporal_layer_profile = kNoTemporalLayerProfile;
}
settings_.maxBitrate = 100;