Enable configuration of OpenH264 Encoder (pion#409)

There's been a long-standing TODO comment in the bridge for OpenH264 to
remove hardcoding for the set of configurable parameters exposed by that
library. That patch does exactly that.

pkg/codec/openh264/bridge.cpp

@@ -21,29 +21,26 @@ Encoder *enc_new(const EncoderOptions opts, int *eresult) {
     return NULL;
   }
 
-  // TODO: Remove hardcoded values
-  params.iUsageType = CAMERA_VIDEO_REAL_TIME;
+  params.iUsageType = opts.usage_type;
   params.iPicWidth = opts.width;
   params.iPicHeight = opts.height;
   params.iTargetBitrate = opts.target_bitrate;
   params.iMaxBitrate = opts.target_bitrate;
-  params.iRCMode = RC_BITRATE_MODE;
+  params.iRCMode = opts.rc_mode;
   params.fMaxFrameRate = opts.max_fps;
-  params.bEnableFrameSkip = true;
-  params.uiMaxNalSize = 0;
-  params.uiIntraPeriod = 30;
-  // set to 0, so that it'll automatically use multi threads when needed
-  params.iMultipleThreadIdc = 0;
+  params.bEnableFrameSkip = opts.enable_frame_skip;
+  params.uiMaxNalSize = opts.max_nal_size;
+  params.uiIntraPeriod = opts.intra_period;
+  params.iMultipleThreadIdc = opts.multiple_thread_idc;
   // The base spatial layer 0 is the only one we use.
   params.sSpatialLayers[0].iVideoWidth = params.iPicWidth;
   params.sSpatialLayers[0].iVideoHeight = params.iPicHeight;
   params.sSpatialLayers[0].fFrameRate = params.fMaxFrameRate;
   params.sSpatialLayers[0].iSpatialBitrate = params.iTargetBitrate;
   params.sSpatialLayers[0].iMaxSpatialBitrate = params.iTargetBitrate;
-  // Single NAL unit mode
-  params.sSpatialLayers[0].sSliceArgument.uiSliceNum = 1;
-  params.sSpatialLayers[0].sSliceArgument.uiSliceMode = SM_SIZELIMITED_SLICE;
-  params.sSpatialLayers[0].sSliceArgument.uiSliceSizeConstraint = 12800;
+  params.sSpatialLayers[0].sSliceArgument.uiSliceNum = opts.slice_num;
+  params.sSpatialLayers[0].sSliceArgument.uiSliceMode = opts.slice_mode;
+  params.sSpatialLayers[0].sSliceArgument.uiSliceSizeConstraint = opts.slice_size_constraint;
 
   rv = engine->InitializeExt(&params);
   if (rv != 0) {

pkg/codec/openh264/bridge.hpp

@@ -22,6 +22,15 @@ typedef struct EncoderOptions {
   int width, height;
   int target_bitrate;
   float max_fps;
+  EUsageType usage_type;
+  RC_MODES rc_mode;
+  bool enable_frame_skip;
+  unsigned int max_nal_size;
+  unsigned int intra_period;
+  int multiple_thread_idc;
+  unsigned int slice_num;
+  SliceModeEnum slice_mode;
+  unsigned int slice_size_constraint;
 } EncoderOptions;
 
 typedef struct Encoder {

pkg/codec/openh264/openh264.go

@@ -33,10 +33,19 @@ func newEncoder(r video.Reader, p prop.Media, params Params) (codec.ReadCloser,
 
 	var rv C.int
 	cEncoder := C.enc_new(C.EncoderOptions{
-		width:          C.int(p.Width),
-		height:         C.int(p.Height),
-		target_bitrate: C.int(params.BitRate),
-		max_fps:        C.float(p.FrameRate),
+		width:                 C.int(p.Width),
+		height:                C.int(p.Height),
+		target_bitrate:        C.int(params.BitRate),
+		max_fps:               C.float(p.FrameRate),
+		usage_type:            C.EUsageType(params.UsageType),
+		rc_mode:               C.RC_MODES(params.RCMode),
+		enable_frame_skip:     C.bool(params.EnableFrameSkip),
+		max_nal_size:          C.uint(params.MaxNalSize),
+		intra_period:          C.uint(params.IntraPeriod),
+		multiple_thread_idc:   C.int(params.MultipleThreadIdc),
+		slice_num:             C.uint(params.SliceNum),
+		slice_mode:            C.SliceModeEnum(params.SliceMode),
+		slice_size_constraint: C.uint(params.SliceSizeConstraint),
 	}, &rv)
 	if err := errResult(rv); err != nil {
 		return nil, fmt.Errorf("failed in creating encoder: %v", err)

pkg/codec/openh264/params.go

@@ -1,5 +1,8 @@
 package openh264
 
+// #include <openh264/codec_api.h>
+import "C"
+
 import (
 	"github.com/pion/mediadevices/pkg/codec"
 	"github.com/pion/mediadevices/pkg/io/video"
@@ -9,14 +12,62 @@ import (
 // Params stores libopenh264 specific encoding parameters.
 type Params struct {
 	codec.BaseParams
+	UsageType           UsageTypeEnum
+	RCMode              RCModeEnum
+	EnableFrameSkip     bool
+	MaxNalSize          uint
+	IntraPeriod         uint
+	MultipleThreadIdc   int
+	SliceNum            uint
+	SliceMode           SliceModeEnum
+	SliceSizeConstraint uint
 }
 
+type UsageTypeEnum int
+
+const (
+	CameraVideoRealTime      UsageTypeEnum = C.CAMERA_VIDEO_REAL_TIME   ///< camera video for real-time communication
+	ScreenContentRealTime    UsageTypeEnum = C.SCREEN_CONTENT_REAL_TIME ///< screen content signal
+	CameraVideoNonRealTime   UsageTypeEnum = C.CAMERA_VIDEO_NON_REAL_TIME
+	ScreenContentNonRealTime UsageTypeEnum = C.SCREEN_CONTENT_NON_REAL_TIME
+	InputContentTypeAll      UsageTypeEnum = C.INPUT_CONTENT_TYPE_ALL
+)
+
+type RCModeEnum int
+
+const (
+	RCQualityMode         RCModeEnum = C.RC_QUALITY_MODE           ///< quality mode
+	RCBitrateMode         RCModeEnum = C.RC_BITRATE_MODE           ///< bitrate mode
+	RCBufferbaseedMode    RCModeEnum = C.RC_BUFFERBASED_MODE       ///< no bitrate control,only using buffer status,adjust the video quality
+	RCTimestampMode       RCModeEnum = C.RC_TIMESTAMP_MODE         //rate control based timestamp
+	RCBitrateModePostSkip RCModeEnum = C.RC_BITRATE_MODE_POST_SKIP ///< this is in-building RC MODE, WILL BE DELETED after algorithm tuning!
+	RCOffMode             RCModeEnum = C.RC_OFF_MODE               ///< rate control off mode
+)
+
+type SliceModeEnum uint
+
+const (
+	SMSingleSlice      SliceModeEnum = C.SM_SINGLE_SLICE      ///< | SliceNum==1
+	SMFixedslcnumSlice SliceModeEnum = C.SM_FIXEDSLCNUM_SLICE ///< | according to SliceNum        | enabled dynamic slicing for multi-thread
+	SMRasterSlice      SliceModeEnum = C.SM_RASTER_SLICE      ///< | according to SlicesAssign    | need input of MB numbers each slice. In addition, if other constraint in SSliceArgument is presented, need to follow the constraints. Typically if MB num and slice size are both constrained, re-encoding may be involved.
+	SMSizelimitedSlice SliceModeEnum = C.SM_SIZELIMITED_SLICE ///< | according to SliceSize       | slicing according to size, the slicing will be dynamic(have no idea about slice_nums until encoding current frame)
+)
+
 // NewParams returns default openh264 codec specific parameters.
 func NewParams() (Params, error) {
 	return Params{
 		BaseParams: codec.BaseParams{
 			BitRate: 100000,
 		},
+		UsageType:           CameraVideoRealTime,
+		RCMode:              RCBitrateMode,
+		EnableFrameSkip:     true,
+		MaxNalSize:          0,
+		IntraPeriod:         30,
+		MultipleThreadIdc:   0, // Defaults to 0, so that it'll automatically use multi threads when needed
+		SliceNum:            1, // Defaults to single NAL unit mode
+		SliceMode:           SMSizelimitedSlice,
+		SliceSizeConstraint: 12800,
 	}, nil
 }