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- package transcoder
- import (
- "bufio"
- "fmt"
- "io"
- "os/exec"
- "strconv"
- "strings"
- log "github.com/sirupsen/logrus"
- "github.com/teris-io/shortid"
- "github.com/owncast/owncast/config"
- "github.com/owncast/owncast/core/data"
- "github.com/owncast/owncast/logging"
- "github.com/owncast/owncast/models"
- "github.com/owncast/owncast/utils"
- )
- var _commandExec *exec.Cmd
- // Transcoder is a single instance of a video transcoder.
- type Transcoder struct {
- codec Codec
- stdin *io.PipeReader
- TranscoderCompleted func(error)
- playlistOutputPath string
- ffmpegPath string
- segmentIdentifier string
- internalListenerPort string
- input string
- segmentOutputPath string
- variants []HLSVariant
- currentStreamOutputSettings []models.StreamOutputVariant
- currentLatencyLevel models.LatencyLevel
- appendToStream bool
- isEvent bool
- }
- // HLSVariant is a combination of settings that results in a single HLS stream.
- type HLSVariant struct {
- audioBitrate string // The audio bitrate
- videoSize VideoSize // Resizes the video via scaling
- index int
- framerate int // The output framerate
- videoBitrate int // The output bitrate
- cpuUsageLevel int // The amount of hardware to use for encoding a stream
- isVideoPassthrough bool // Override all settings and just copy the video stream
- isAudioPassthrough bool // Override all settings and just copy the audio stream
- }
- // VideoSize is the scaled size of the video output.
- type VideoSize struct {
- Width int
- Height int
- }
- // For limiting the output bitrate
- // https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
- // https://developer.apple.com/documentation/http_live_streaming/about_apple_s_http_live_streaming_tools
- // Adjust the max & buffer size until the output bitrate doesn't exceed the ~+10% that Apple's media validator
- // complains about.
- // getAllocatedVideoBitrate returns the video bitrate we allocate after making some room for audio.
- // 192 is pretty average.
- func (v *HLSVariant) getAllocatedVideoBitrate() int {
- return int(float64(v.videoBitrate) - 192)
- }
- // getMaxVideoBitrate returns the maximum video bitrate we allow the encoder to support.
- func (v *HLSVariant) getMaxVideoBitrate() int {
- return int(float64(v.getAllocatedVideoBitrate()) * 1.08)
- }
- // getBufferSize returns how often it checks the bitrate of encoded segments to see if it's too high/low.
- func (v *HLSVariant) getBufferSize() int {
- return int(float64(v.getMaxVideoBitrate()))
- }
- // getString returns a WxH formatted getString for scaling video output.
- func (v *VideoSize) getString() string {
- widthString := strconv.Itoa(v.Width)
- heightString := strconv.Itoa(v.Height)
- if widthString != "0" && heightString != "0" {
- return widthString + ":" + heightString
- } else if widthString != "0" {
- return widthString + ":-2"
- } else if heightString != "0" {
- return "-2:" + heightString
- }
- return ""
- }
- // Stop will stop the transcoder and kill all processing.
- func (t *Transcoder) Stop() {
- log.Traceln("Transcoder STOP requested.")
- err := _commandExec.Process.Kill()
- if err != nil {
- log.Errorln(err)
- }
- }
- // Start will execute the transcoding process with the settings previously set.
- func (t *Transcoder) Start(shouldLog bool) {
- _lastTranscoderLogMessage = ""
- command := t.getString()
- if shouldLog {
- log.Infof("Processing video using codec %s with %d output qualities configured.", t.codec.DisplayName(), len(t.variants))
- }
- createVariantDirectories()
- if config.EnableDebugFeatures {
- log.Println(command)
- }
- _commandExec = exec.Command("sh", "-c", command)
- if t.stdin != nil {
- _commandExec.Stdin = t.stdin
- }
- stdout, err := _commandExec.StderrPipe()
- if err != nil {
- log.Fatalln(err)
- }
- if err := _commandExec.Start(); err != nil {
- log.Errorln("Transcoder error. See", logging.GetTranscoderLogFilePath(), "for full output to debug.")
- log.Panicln(err, command)
- }
- go func() {
- scanner := bufio.NewScanner(stdout)
- for scanner.Scan() {
- line := scanner.Text()
- handleTranscoderMessage(line)
- }
- }()
- err = _commandExec.Wait()
- if t.TranscoderCompleted != nil {
- t.TranscoderCompleted(err)
- }
- if err != nil {
- log.Errorln("transcoding error. look at", logging.GetTranscoderLogFilePath(), "to help debug. your copy of ffmpeg may not support your selected codec of", t.codec.Name(), "https://owncast.online/docs/codecs/")
- }
- }
- // SetLatencyLevel will set the latency level for the instance of the transcoder.
- func (t *Transcoder) SetLatencyLevel(level models.LatencyLevel) {
- t.currentLatencyLevel = level
- }
- // SetIsEvent will allow you to set a stream as an "event".
- func (t *Transcoder) SetIsEvent(isEvent bool) {
- t.isEvent = isEvent
- }
- func (t *Transcoder) getString() string {
- port := t.internalListenerPort
- localListenerAddress := "http://127.0.0.1:" + port
- hlsOptionFlags := []string{
- "program_date_time",
- "independent_segments",
- }
- if t.appendToStream {
- hlsOptionFlags = append(hlsOptionFlags, "append_list")
- }
- if t.segmentIdentifier == "" {
- t.segmentIdentifier = shortid.MustGenerate()
- }
- hlsEventString := ""
- if t.isEvent {
- hlsEventString = "-hls_playlist_type event"
- } else {
- // Don't let the transcoder close the playlist. We do it manually.
- hlsOptionFlags = append(hlsOptionFlags, "omit_endlist")
- }
- hlsOptionsString := ""
- if len(hlsOptionFlags) > 0 {
- hlsOptionsString = "-hls_flags " + strings.Join(hlsOptionFlags, "+")
- }
- ffmpegFlags := []string{
- fmt.Sprintf(`FFREPORT=file="%s":level=32`, logging.GetTranscoderLogFilePath()),
- t.ffmpegPath,
- "-hide_banner",
- "-loglevel warning",
- t.codec.GlobalFlags(),
- "-fflags +genpts", // Generate presentation time stamp if missing
- "-flags +cgop", // Force closed GOPs
- "-i ", t.input,
- t.getVariantsString(),
- // HLS Output
- "-f", "hls",
- "-hls_time", strconv.Itoa(t.currentLatencyLevel.SecondsPerSegment), // Length of each segment
- "-hls_list_size", strconv.Itoa(t.currentLatencyLevel.SegmentCount), // Max # in variant playlist
- hlsOptionsString,
- hlsEventString,
- "-segment_format_options", "mpegts_flags=mpegts_copyts=1",
- // Video settings
- t.codec.ExtraArguments(),
- "-pix_fmt", t.codec.PixelFormat(),
- "-sc_threshold", "0", // Disable scene change detection for creating segments
- // Filenames
- "-master_pl_name", "stream.m3u8",
- "-hls_segment_filename", localListenerAddress + "/%v/stream-" + t.segmentIdentifier + "-%d.ts", // Send HLS segments back to us over HTTP
- "-max_muxing_queue_size", "400", // Workaround for Too many packets error: https://trac.ffmpeg.org/ticket/6375?cversion=0
- "-method PUT", // HLS results sent back to us will be over PUTs
- localListenerAddress + "/%v/stream.m3u8", // Send HLS playlists back to us over HTTP
- }
- return strings.Join(ffmpegFlags, " ")
- }
- func getVariantFromConfigQuality(quality models.StreamOutputVariant, index int) HLSVariant {
- variant := HLSVariant{}
- variant.index = index
- variant.isAudioPassthrough = quality.IsAudioPassthrough
- variant.isVideoPassthrough = quality.IsVideoPassthrough
- // If no audio bitrate is specified then we pass through original audio
- if quality.AudioBitrate == 0 {
- variant.isAudioPassthrough = true
- }
- if quality.VideoBitrate == 0 {
- quality.VideoBitrate = 1200
- }
- // If the video is being passed through then
- // don't continue to set options on the variant.
- if variant.isVideoPassthrough {
- return variant
- }
- // Set a default, reasonable preset if one is not provided.
- // "superfast" and "ultrafast" are generally not recommended since they look bad.
- // https://trac.ffmpeg.org/wiki/Encode/H.264
- variant.cpuUsageLevel = quality.CPUUsageLevel
- variant.SetVideoBitrate(quality.VideoBitrate)
- variant.SetAudioBitrate(strconv.Itoa(quality.AudioBitrate) + "k")
- variant.SetVideoScalingWidth(quality.ScaledWidth)
- variant.SetVideoScalingHeight(quality.ScaledHeight)
- variant.SetVideoFramerate(quality.GetFramerate())
- return variant
- }
- // NewTranscoder will return a new Transcoder, populated by the config.
- func NewTranscoder() *Transcoder {
- ffmpegPath := utils.ValidatedFfmpegPath(data.GetFfMpegPath())
- transcoder := new(Transcoder)
- transcoder.ffmpegPath = ffmpegPath
- transcoder.internalListenerPort = config.InternalHLSListenerPort
- transcoder.currentStreamOutputSettings = data.GetStreamOutputVariants()
- transcoder.currentLatencyLevel = data.GetStreamLatencyLevel()
- transcoder.codec = getCodec(data.GetVideoCodec())
- transcoder.segmentOutputPath = config.HLSStoragePath
- transcoder.playlistOutputPath = config.HLSStoragePath
- transcoder.input = "pipe:0" // stdin
- for index, quality := range transcoder.currentStreamOutputSettings {
- variant := getVariantFromConfigQuality(quality, index)
- transcoder.AddVariant(variant)
- }
- return transcoder
- }
- // Uses `map` https://www.ffmpeg.org/ffmpeg-all.html#Stream-specifiers-1 https://www.ffmpeg.org/ffmpeg-all.html#Advanced-options
- func (v *HLSVariant) getVariantString(t *Transcoder) string {
- variantEncoderCommands := []string{
- v.getVideoQualityString(t),
- v.getAudioQualityString(),
- }
- if (v.videoSize.Width != 0 || v.videoSize.Height != 0) && !v.isVideoPassthrough {
- // Order here matters, you must scale before changing hardware formats
- filters := []string{
- v.getScalingString(t.codec.Scaler()),
- }
- if t.codec.ExtraFilters() != "" {
- filters = append(filters, t.codec.ExtraFilters())
- }
- scalingAlgorithm := "bilinear"
- filterString := fmt.Sprintf("-sws_flags %s -filter:v:%d \"%s\"", scalingAlgorithm, v.index, strings.Join(filters, ","))
- variantEncoderCommands = append(variantEncoderCommands, filterString)
- } else if t.codec.ExtraFilters() != "" && !v.isVideoPassthrough {
- filterString := fmt.Sprintf("-filter:v:%d \"%s\"", v.index, t.codec.ExtraFilters())
- variantEncoderCommands = append(variantEncoderCommands, filterString)
- }
- preset := t.codec.GetPresetForLevel(v.cpuUsageLevel)
- if preset != "" {
- variantEncoderCommands = append(variantEncoderCommands, fmt.Sprintf("-preset %s", preset))
- }
- return strings.Join(variantEncoderCommands, " ")
- }
- // Get the command flags for the variants.
- func (t *Transcoder) getVariantsString() string {
- variantsCommandFlags := ""
- variantsStreamMaps := " -var_stream_map \""
- for _, variant := range t.variants {
- variantsCommandFlags = variantsCommandFlags + " " + variant.getVariantString(t)
- singleVariantMap := fmt.Sprintf("v:%d,a:%d ", variant.index, variant.index)
- variantsStreamMaps += singleVariantMap
- }
- variantsCommandFlags = variantsCommandFlags + " " + variantsStreamMaps + "\""
- return variantsCommandFlags
- }
- // Video Scaling
- // https://trac.ffmpeg.org/wiki/Scaling
- // If we'd like to keep the aspect ratio, we need to specify only one component, either width or height.
- // Some codecs require the size of width and height to be a multiple of n. You can achieve this by setting the width or height to -n.
- // SetVideoScalingWidth will set the scaled video width of this variant.
- func (v *HLSVariant) SetVideoScalingWidth(width int) {
- v.videoSize.Width = width
- }
- // SetVideoScalingHeight will set the scaled video height of this variant.
- func (v *HLSVariant) SetVideoScalingHeight(height int) {
- v.videoSize.Height = height
- }
- func (v *HLSVariant) getScalingString(scaler string) string {
- if scaler == "" {
- scaler = "scale"
- }
- return fmt.Sprintf("%s=%s", scaler, v.videoSize.getString())
- }
- // Video Quality
- // SetVideoBitrate will set the output bitrate of this variant's video.
- func (v *HLSVariant) SetVideoBitrate(bitrate int) {
- v.videoBitrate = bitrate
- }
- func (v *HLSVariant) getVideoQualityString(t *Transcoder) string {
- if v.isVideoPassthrough {
- return fmt.Sprintf("-map v:0 -c:v:%d copy", v.index)
- }
- gop := v.framerate * t.currentLatencyLevel.SecondsPerSegment // force an i-frame every segment
- cmd := []string{
- "-map v:0",
- fmt.Sprintf("-c:v:%d %s", v.index, t.codec.Name()), // Video codec used for this variant
- fmt.Sprintf("-b:v:%d %dk", v.index, v.getAllocatedVideoBitrate()), // The average bitrate for this variant allowing space for audio
- fmt.Sprintf("-maxrate:v:%d %dk", v.index, v.getMaxVideoBitrate()), // The max bitrate allowed for this variant
- fmt.Sprintf("-g:v:%d %d", v.index, gop), // Suggested interval where i-frames are encoded into the segments
- fmt.Sprintf("-keyint_min:v:%d %d", v.index, gop), // minimum i-keyframe interval
- fmt.Sprintf("-r:v:%d %d", v.index, v.framerate),
- t.codec.VariantFlags(v),
- }
- return strings.Join(cmd, " ")
- }
- // SetVideoFramerate will set the output framerate of this variant's video.
- func (v *HLSVariant) SetVideoFramerate(framerate int) {
- v.framerate = framerate
- }
- // SetCPUUsageLevel will set the hardware usage of this variant.
- func (v *HLSVariant) SetCPUUsageLevel(level int) {
- v.cpuUsageLevel = level
- }
- // Audio Quality
- // SetAudioBitrate will set the output framerate of this variant's audio.
- func (v *HLSVariant) SetAudioBitrate(bitrate string) {
- v.audioBitrate = bitrate
- }
- func (v *HLSVariant) getAudioQualityString() string {
- if v.isAudioPassthrough {
- return fmt.Sprintf("-map a:0? -c:a:%d copy", v.index)
- }
- // libfdk_aac is not a part of every ffmpeg install, so use "aac" instead
- encoderCodec := "aac"
- return fmt.Sprintf("-map a:0? -c:a:%d %s -b:a:%d %s", v.index, encoderCodec, v.index, v.audioBitrate)
- }
- // AddVariant adds a new HLS variant to include in the output.
- func (t *Transcoder) AddVariant(variant HLSVariant) {
- variant.index = len(t.variants)
- t.variants = append(t.variants, variant)
- }
- // SetInput sets the input stream on the filesystem.
- func (t *Transcoder) SetInput(input string) {
- t.input = input
- }
- // SetStdin sets the Stdin of the ffmpeg command.
- func (t *Transcoder) SetStdin(pipe *io.PipeReader) {
- t.stdin = pipe
- }
- // SetOutputPath sets the root directory that should include playlists and video segments.
- func (t *Transcoder) SetOutputPath(output string) {
- t.segmentOutputPath = output
- }
- // SetIdentifier enables appending a unique identifier to segment file name.
- func (t *Transcoder) SetIdentifier(output string) {
- t.segmentIdentifier = output
- }
- // SetInternalHTTPPort will set the port to be used for internal communication.
- func (t *Transcoder) SetInternalHTTPPort(port string) {
- t.internalListenerPort = port
- }
- // SetCodec will set the codec to be used for the transocder.
- func (t *Transcoder) SetCodec(codecName string) {
- t.codec = getCodec(codecName)
- }
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