move filters and add codec context setters

internal/controllers/engine/donut_engine_controller.go

@@ -114,14 +114,20 @@ func (d *donutEngine) RecipeFor(server, client *entities.StreamInfo) (*entities.
 	r := &entities.DonutRecipe{
 		Input: appetizer,
 		Video: entities.DonutMediaTask{
+			// Action:               entities.DonutTranscode,
 			Action:               entities.DonutBypass,
 			Codec:                entities.H264,
 			DonutBitStreamFilter: &entities.DonutH264AnnexB,
+			// CodecContextOptions: []entities.LibAVOptionsCodecContext{
+			// 	entities.SetBitRate(100_000),
+			// 	entities.SetBaselineProfile(),
+			// 	entities.SetGopSize(30),
+			// },
 		},
 		Audio: entities.DonutMediaTask{
 			Action:            entities.DonutTranscode,
 			Codec:             entities.Opus,
-			// TODO: create method list options per Codec
+			DonutStreamFilter: entities.AudioResamplerFilter(48000),
 			CodecContextOptions: []entities.LibAVOptionsCodecContext{
 				entities.SetSampleRate(48000),
 				entities.SetSampleFormat("fltp"),

internal/controllers/streamers/libav_ffmpeg.go

@@ -391,10 +391,11 @@ func (c *LibAVFFmpegStreamer) prepareFilters(p *libAVParams, closer *astikit.Clo
 			}
 			buffersrc = astiav.FindFilterByName("abuffer")
 			buffersink = astiav.FindFilterByName("abuffersink")
-			content = fmt.Sprintf(
+			if donut.Recipe.Audio.DonutStreamFilter != nil {
-				"aresample=%s", // necessary for opus
+				content = string(*donut.Recipe.Audio.DonutStreamFilter)
-				strconv.Itoa(s.encCodecContext.SampleRate()),
+			} else {
-			)
+				content = "anull" /* passthrough (dummy) filter for audio */
+			}
 		}
 
 		if isVideo {
@@ -406,7 +407,11 @@ func (c *LibAVFFmpegStreamer) prepareFilters(p *libAVParams, closer *astikit.Clo
 			}
 			buffersrc = astiav.FindFilterByName("buffer")
 			buffersink = astiav.FindFilterByName("buffersink")
-			content = fmt.Sprintf("format=pix_fmts=%s", s.encCodecContext.PixelFormat().Name())
+			if donut.Recipe.Video.DonutStreamFilter != nil {
+				content = string(*donut.Recipe.Video.DonutStreamFilter)
+			} else {
+				content = "null" /* passthrough (dummy) filter for video */
+			}
 		}
 
 		if buffersrc == nil {

internal/entities/entities.go

@@ -156,6 +156,13 @@ type DonutBitStreamFilter string
 
 var DonutH264AnnexB DonutBitStreamFilter = "h264_mp4toannexb"
 
+type DonutStreamFilter string
+
+func AudioResamplerFilter(sampleRate int) *DonutStreamFilter {
+	filter := DonutStreamFilter(fmt.Sprintf("aresample=%d", sampleRate))
+	return &filter
+}
+
 // TODO: split entities per domain or files avoiding name collision.
 
 // DonutMediaTask is a transformation template to apply over a media.
@@ -171,6 +178,9 @@ type DonutMediaTask struct {
 
 	// DonutBitStreamFilter is the bitstream filter
 	DonutBitStreamFilter *DonutBitStreamFilter
+
+	// DonutStreamFilter is a regular filter
+	DonutStreamFilter *DonutStreamFilter
 }
 
 type DonutInputOptionKey string
@@ -220,6 +230,24 @@ func SetTimeBase(num, den int) LibAVOptionsCodecContext {
 	}
 }
 
+func SetBitRate(bitRate int64) LibAVOptionsCodecContext {
+	return func(c *astiav.CodecContext) {
+		c.SetBitRate(bitRate)
+	}
+}
+
+func SetBaselineProfile() LibAVOptionsCodecContext {
+	return func(c *astiav.CodecContext) {
+		c.SetProfile(astiav.ProfileH264Baseline)
+	}
+}
+
+func SetGopSize(gopSize int) LibAVOptionsCodecContext {
+	return func(c *astiav.CodecContext) {
+		c.SetGopSize(gopSize)
+	}
+}
+
 // SetSampleFormat sets sample format,
 // CAUTION it only contains partial list of fmt
 // TODO: move it to mappers