owncast/core/transcoder/transcoder.go
2021-10-25 00:31:45 -07:00

416 lines
13 KiB
Go

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 {
input string
stdin *io.PipeReader
segmentOutputPath string
playlistOutputPath string
variants []HLSVariant
appendToStream bool
ffmpegPath string
segmentIdentifier string
internalListenerPort string
codec Codec
currentStreamOutputSettings []models.StreamOutputVariant
currentLatencyLevel models.LatencyLevel
TranscoderCompleted func(error)
}
// HLSVariant is a combination of settings that results in a single HLS stream.
type HLSVariant struct {
index int
videoSize VideoSize // Resizes the video via scaling
framerate int // The output framerate
videoBitrate int // The output bitrate
isVideoPassthrough bool // Override all settings and just copy the video stream
audioBitrate string // The audio bitrate
isAudioPassthrough bool // Override all settings and just copy the audio stream
cpuUsageLevel int // The amount of hardware to use for encoding a stream
}
// VideoSize is the scaled size of the video output.
type VideoSize struct {
Width int
Height int
}
// 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() {
_lastTranscoderLogMessage = ""
command := t.getString()
log.Infof("Video transcoder started using %s with %d stream variants.", 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/")
}
}
func (t *Transcoder) getString() string {
var port = t.internalListenerPort
localListenerAddress := "http://127.0.0.1:" + port
hlsOptionFlags := []string{}
if t.appendToStream {
hlsOptionFlags = append(hlsOptionFlags, "append_list")
}
if t.segmentIdentifier == "" {
t.segmentIdentifier = shortid.MustGenerate()
}
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
"-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,
"-segment_format_options", "mpegts_flags=+initial_discontinuity: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",
"-strftime 1", // Support the use of strftime in filenames
"-hls_segment_filename", localListenerAddress + "/%v/stream-" + t.segmentIdentifier + "%s.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 -http_persistent 0", // 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(),
}
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 {
var variantsCommandFlags = ""
var 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() string {
return fmt.Sprintf("scale=%s", 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
// 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.
maxBitrate := int(float64(v.videoBitrate) * 1.06) // Max is a ~+10% over specified bitrate.
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.videoBitrate), // The average bitrate for this variant
fmt.Sprintf("-maxrate:v:%d %dk", v.index, maxBitrate), // 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
}
// SetAppendToStream enables appending to the HLS stream instead of overwriting.
func (t *Transcoder) SetAppendToStream(append bool) {
t.appendToStream = append
}
// 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)
}