golang/owncast
1
0
Fork 0
mirror of https://github.com/owncast/owncast.git synced 2025-11-01 10:55:57 +08:00
Code Issues Packages Projects Releases Wiki Activity

Codec selection (#892)

Browse Source 
* Query for installed codecs

* Start modeling out codecs

* Can now specify a codec and get the correct settings returned from the model

* Return codecs in admin/serverconfig

* Start handling transcoding errors and return messages to user

* filter available codecs against a whitelist

* Fix merge

* Codecs are working

* Switching between codecs work

* Add apis for setting a custom video codec

* Cleanup the logging of transcoder errors

* Add v4l codec

* Add fetching v4l

* Add support for per-codec presets

* Use updated nvenc encoding parameters

* Update log message

* Some more codec WIP

* Turn off v4l. It is a mess.

* Try to make the lowest latency level a bit more playable

* Use a human redable display name in console messages

* Turn on transcoder persistent connections

* Add more codec-related user-facing error messages

* Give the initial offline state transcoder an id

* Force a minimum segment count of 3

* Disable qsv for now. set x264 specific params in VariantFlags

* Close body in case

* Ignore vbv underflow message, it is not actionable

* Determine a dynamic gop value based on the length of segments

* Add codec-specific tests

* Cleanup

* Ignore goconst lint warnings in codec file

* Troubleshoot omx

* Add more codec tests

* Remove no longer accurate comment

* Bundle admin from codec branch

* Revert back to old setting

* Cleanup list of codecs a bit

* Remove old references to the encoder preset

* Commit updated API documentation

* Update admin bundle

* Commit updated API documentation

* Add codec setting to api spec

* Commit updated API documentation

Co-authored-by: Owncast <owncast@owncast.online>
This commit is contained in:
Gabe Kangas
2021-04-15 13:55:51 -07:00
committed by GitHub
parent 7dec4fe063
commit 5214d81264
21 changed files with 845 additions and 180 deletions
Download Patch File Download Diff File Expand all files Collapse all files

99
core/transcoder/transcoder.go
View File

@ -1,6 +1,7 @@
package transcoder
import (
"bufio"
"fmt"
"os/exec"
"strconv"
@ -27,6 +28,7 @@ type Transcoder struct {
ffmpegPath string
segmentIdentifier string
internalListenerPort string
codec Codec
currentStreamOutputSettings []models.StreamOutputVariant
currentLatencyLevel models.LatencyLevel
@ -46,7 +48,7 @@ type HLSVariant struct {
audioBitrate string // The audio bitrate
isAudioPassthrough bool // Override all settings and just copy the audio stream
encoderPreset string // A collection of automatic settings for the encoder. https://trac.ffmpeg.org/wiki/Encode/H.264#crf
cpuUsageLevel int // The amount of hardware to use for encoding a stream
}
// VideoSize is the scaled size of the video output.
@ -81,25 +83,43 @@ func (t *Transcoder) Stop() {
// Start will execute the transcoding process with the settings previously set.
func (t *Transcoder) Start() {
command := t.getString()
_lastTranscoderLogMessage = ""
log.Tracef("Video transcoder started with %d stream variants.", len(t.variants))
command := t.getString()
log.Infof("Video transcoder started using %s with %d stream variants.", t.codec.DisplayName(), len(t.variants))
if config.EnableDebugFeatures {
log.Println(command)
}
_commandExec = exec.Command("sh", "-c", command)
err := _commandExec.Start()
stdout, err := _commandExec.StderrPipe()
if err != nil {
panic(err)
}
err = _commandExec.Start()
if err != nil {
log.Errorln("Transcoder error. See transcoder.log 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 transcoder.log to help debug. your copy of ffmpeg may not support your selected codec of", t.codec.Name(), "https://owncast.online/docs/troubleshooting/#codecs")
}
}
func (t *Transcoder) getString() string {
@ -121,9 +141,12 @@ func (t *Transcoder) getString() string {
hlsOptionsString = "-hls_flags " + strings.Join(hlsOptionFlags, "+")
}
ffmpegFlags := []string{
`FFREPORT=file="transcoder.log":level=32`,
t.ffmpegPath,
"-hide_banner",
"-loglevel warning",
t.codec.GlobalFlags(),
"-fflags +genpts", // Generate presentation time stamp if missing
"-i ", t.input,
t.getVariantsString(),
@ -133,12 +156,12 @@ func (t *Transcoder) getString() string {
"-hls_time", strconv.Itoa(t.currentLatencyLevel.SecondsPerSegment), // Length of each segment
"-hls_list_size", strconv.Itoa(t.currentLatencyLevel.SegmentCount), // Max # in variant playlist
"-hls_delete_threshold", "10", // Start deleting files after hls_list_size + 10
hlsOptionsString,
"-segment_format_options", "mpegts_flags=+initial_discontinuity:mpegts_copyts=1",
// Video settings
"-tune", "zerolatency", // Option used for good for fast encoding and low-latency streaming (always includes iframes in each segment)
"-pix_fmt", "yuv420p", // Force yuv420p color format
t.codec.ExtraArguments(),
"-pix_fmt", t.codec.PixelFormat(),
"-sc_threshold", "0", // Disable scene change detection for creating segments
// Filenames
@ -149,9 +172,7 @@ func (t *Transcoder) getString() string {
"-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
"-fflags +genpts", // Generate presentation time stamp if missing
localListenerAddress + "/%v/stream.m3u8", // Send HLS playlists back to us over HTTP
"2> transcoder.log", // Log to a file for debugging
}
return strings.Join(ffmpegFlags, " ")
@ -181,7 +202,7 @@ func getVariantFromConfigQuality(quality models.StreamOutputVariant, index int)
// 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.encoderPreset = quality.GetEncoderPreset()
variant.cpuUsageLevel = quality.CPUUsageLevel
variant.SetVideoBitrate(quality.VideoBitrate)
variant.SetAudioBitrate(strconv.Itoa(quality.AudioBitrate) + "k")
@ -202,6 +223,7 @@ func NewTranscoder() *Transcoder {
transcoder.currentStreamOutputSettings = data.GetStreamOutputVariants()
transcoder.currentLatencyLevel = data.GetStreamLatencyLevel()
transcoder.codec = getCodec(data.GetVideoCodec())
var outputPath string
if data.GetS3Config().Enabled {
@ -233,12 +255,25 @@ func (v *HLSVariant) getVariantString(t *Transcoder) string {
v.getAudioQualityString(),
}
if v.videoSize.Width != 0 || v.videoSize.Height != 0 {
variantEncoderCommands = append(variantEncoderCommands, v.getScalingString())
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)
}
if v.encoderPreset != "" {
variantEncoderCommands = append(variantEncoderCommands, fmt.Sprintf("-preset %s", v.encoderPreset))
preset := t.codec.GetPresetForLevel(v.cpuUsageLevel)
if preset != "" {
variantEncoderCommands = append(variantEncoderCommands, fmt.Sprintf("-preset %s", preset))
}
return strings.Join(variantEncoderCommands, " ")
@ -276,8 +311,7 @@ func (v *HLSVariant) SetVideoScalingHeight(height int) {
}
func (v *HLSVariant) getScalingString() string {
scalingAlgorithm := "bilinear"
return fmt.Sprintf("-filter:v:%d \"scale=%s\" -sws_flags %s", v.index, v.videoSize.getString(), scalingAlgorithm)
return fmt.Sprintf("scale=%s", v.videoSize.getString())
}
// Video Quality
@ -292,11 +326,14 @@ func (v *HLSVariant) getVideoQualityString(t *Transcoder) string {
return fmt.Sprintf("-map v:0 -c:v:%d copy", v.index)
}
encoderCodec := "libx264"
// -1 to work around segments being generated slightly larger than expected.
// https://trac.ffmpeg.org/ticket/6915?replyto=58#comment:57
gop := (t.currentLatencyLevel.SecondsPerSegment * v.framerate) - 1
// Determine if we should force key frames every 1, 2 or 3 frames.
isEven := t.currentLatencyLevel.SecondsPerSegment%2 == 0
gop := v.framerate * 2
if t.currentLatencyLevel.SecondsPerSegment == 1 {
gop = v.framerate
} else if !isEven {
gop = v.framerate * 3
}
// For limiting the output bitrate
// https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
@ -304,18 +341,16 @@ func (v *HLSVariant) getVideoQualityString(t *Transcoder) string {
// 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.
bufferSize := int(float64(v.videoBitrate) * 1.2) // How often it checks the bitrate of encoded segments to see if it's too high/low.
cmd := []string{
"-map v:0",
fmt.Sprintf("-c:v:%d %s", v.index, encoderCodec), // Video codec used for this variant
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("-bufsize:v:%d %dk", v.index, bufferSize), // How often the encoder checks the bitrate in order to meet average/max values
fmt.Sprintf("-g:v:%d %d", v.index, gop), // How often i-frames are encoded into the segments
fmt.Sprintf("-profile:v:%d %s", v.index, "high"), // Encoding profile
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),
fmt.Sprintf("-x264-params:v:%d \"scenecut=0:open_gop=0:min-keyint=%d:keyint=%d\"", v.index, gop, gop), // How often i-frames are encoded into the segments
t.codec.VariantFlags(v),
}
return strings.Join(cmd, " ")
@ -326,9 +361,9 @@ func (v *HLSVariant) SetVideoFramerate(framerate int) {
v.framerate = framerate
}
// SetEncoderPreset will set the video encoder preset of this variant.
func (v *HLSVariant) SetEncoderPreset(preset string) {
v.encoderPreset = preset
// SetCPUUsageLevel will set the hardware usage of this variant.
func (v *HLSVariant) SetCPUUsageLevel(level int) {
v.cpuUsageLevel = level
}
// Audio Quality
@ -377,3 +412,7 @@ func (t *Transcoder) SetIdentifier(output string) {
func (t *Transcoder) SetInternalHTTPPort(port string) {
t.internalListenerPort = port
}
func (t *Transcoder) SetCodec(codecName string) {
t.codec = getCodec(codecName)
}