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r4
2022-09-20 00:54:22 +02:00
commit 4195b20e65
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167
audio/audio.go Normal file
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package audio
import (
"errors"
"io"
"os"
"os/exec"
"strconv"
"strings"
"time"
"fmt"
)
const (
BufferLength = 300 // 5min / 3.6MB
Channels = 1 // unfortunately, Discord doesn't seem to support stereo at the time
BitRate = 96000
SampleRate = 48000
FrameSize = 960 // 960 samples
FrameDuration = float64(FrameSize) / float64(SampleRate) // 20ms
FramesPerSecond = SampleRate / FrameSize
)
var (
ErrNotHttp = errors.New("the requested resource is not an http/https address")
)
type frameIdx struct {
start uint
end uint
}
// Takes a file path/HTTP(S) stream URL and returns Discord audio frames through
// audioFrameCh. After audioFrameCh is closed, errCh can be read to get any
// potential error. Will cleanly kill ffmpeg if a struct{} is sent through
// killCh (IMPORTANT: only send the kill signal ONCE: there is a chance that
// this goroutine exits just before you send a kill signal; this will be
// absorbed by the channel buffer, but your program might get stuck if you try
// to send two kill signals to a dead stream).
func StreamToDiscordOpus(ffmpegPath, input string, stdin io.Reader, seekSeconds float64, playbackSpeed float64, inetOnly bool) (audioFrameCh <-chan []byte, errCh <-chan error, killCh chan<- struct{}) {
out := make(chan []byte, BufferLength*FramesPerSecond)
errch := make(chan error, 1)
killch := make(chan struct{}, 1)
go func() {
defer close(out)
defer close(errch)
if inetOnly && !(strings.HasPrefix(input, "http://") || strings.HasPrefix(input, "https://")) {
errch <- ErrNotHttp
return
}
// Set ffmpeg options
var cmdOpts []string
cmdOpts = append(cmdOpts,
"-vn", // no video
"-sn", // no subs
"-dn") // no data encoding
if seekSeconds != 0.0 {
cmdOpts = append(cmdOpts,
"-accurate_seek",
"-ss", strconv.FormatFloat(seekSeconds, 'f', 5, 64)) // seek duration
}
cmdOpts = append(cmdOpts,
"-i", input)
if playbackSpeed != 1.0 {
cmdOpts = append(cmdOpts,
"-filter:a", "atempo="+strconv.FormatFloat(playbackSpeed, 'f', 5, 64)) // playback speed
}
cmdOpts = append(cmdOpts,
"-ab", strconv.Itoa(BitRate), // audio bit rate
"-ac", strconv.Itoa(Channels), // audio channels
"-frame_size", strconv.Itoa(int(FrameDuration*1000)), // frame size (in ms)
"-f", "opus", // output OPUS audio
"pipe:1") // output to stdout
// Prepare ffmpeg command
cmd := exec.Command(ffmpegPath, cmdOpts...)
if stdin != nil {
cmd.Stdin = stdin
}
stdout, err := cmd.StdoutPipe()
if err != nil {
errch <- err
return
}
// Start ffmpeg
if err := cmd.Start(); err != nil {
errch <- err
return
}
// We want to let our main loop know if ffmpeg is done
donech := make(chan error)
go func() {
donech <- cmd.Wait()
}()
// Ogg decoder
dec := newOggDecoder(stdout)
var segDec *oggSegmentDecoder
startSegDec := false
// Avoid dropping frames
wantNewFrame := true
// Main opus encoder loop
for {
var frame []byte
for wantNewFrame {
if startSegDec && segDec.More() {
frame = make([]byte, segDec.SegmentSize())
if err := segDec.ReadSegment(frame); err != nil {
errch <- err
return
}
wantNewFrame = false
} else if dec.More() {
var err error
var hdr oggPageHeader
hdr, segDec, err = dec.Page()
if err != nil {
errch <- err
return
}
if hdr.GranulePosition != 0 {
startSegDec = true
}
} else {
out = nil
break
}
}
// Channel IO
select {
case err := <-donech:
fmt.Println("Audio done, waiting for read to finish")
if err != nil {
// Send error and exit
errch <- err
return
}
// Process exited normally, wait until all samples are read
// before closing the channels
for len(out) != 0 {
time.Sleep(20 * time.Millisecond)
}
fmt.Println("Audio read finished")
return
case <-killch:
// Process was killed by user
cmd.Process.Signal(os.Interrupt)
return
case out <- frame:
// Output is ready to receive a new frame
wantNewFrame = true
}
}
}()
return out, errch, killch
}

279
audio/ogg.go Normal file
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// Minimal Ogg decoder according to rfc3533
// (https://www.xiph.org/ogg/doc/rfc3533.txt). Whenever 'the spec' is mentioned,
// it is referring to rfc3533.
package audio
import (
"encoding/binary"
"errors"
"io"
)
var (
ErrOggInvalidMagicNumber = errors.New("ogg: invalid magic number")
ErrOggInvalidChecksum = errors.New("ogg: invalid checksum")
ErrOggInvalidSegmentBufferSize = errors.New("ogg: WriteSegment(): invalid segment buffer size")
)
const (
headerSize = 27
// Uncombined segments are meant here (see Page.Segments or the spec for
// more details about segments).
maxSegments = 255
maxSegmentSize = 255
maxPageSize = headerSize + maxSegments + maxSegments*maxSegmentSize
)
// Using polynomial 0x04c11db7 (see the spec).
var crcLookup = [256]uint32{
0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4,
}
type crc32Writer struct {
sum uint32
}
func (w *crc32Writer) Write(p []byte) (n int, err error) {
for _, v := range p {
w.sum = (w.sum << 8) ^ crcLookup[uint8(w.sum>>24)^v]
}
return len(p), nil
}
var (
FHeaderTypeContinuation = uint8(0x1)
FHeaderTypeBOS = uint8(0x2) // Beginning of stream
FHeaderTypeEOS = uint8(0x4) // End of stream
)
// See the spec for more info on the individual fields.
type oggPageHeader struct {
MagicNumber [4]uint8
Version uint8
HeaderType uint8
GranulePosition uint64
BitstreamSerialNum uint32
PageSequenceNum uint32
Checksum uint32
NumSegments uint8 // Number of uncombined segments (see Page.Segments or the spec for more details).
}
type oggPage struct {
Header oggPageHeader
// These are the combined segments. The spec says that when a segment is
// said to have a length of 255, it is to be combined with the next segment,
// which is already done here.
Segments [][]byte
}
type oggDecoder struct {
r io.Reader
sum *crc32Writer
givenSum uint32
done bool
sd *oggSegmentDecoder
}
// An oggDecoder decodes the given raw Ogg data according to rfc3533
// (https://www.xiph.org/ogg/doc/rfc3533.txt).
// The given reader `r` must be set to start at the beginning of the page, i.e.
// at the magic number "OggS".
// The data is dispensed in units of pages, each of which returns a segment
// decoder for getting the individual segments.
func newOggDecoder(r io.Reader) *oggDecoder {
return &oggDecoder{
r: r,
}
}
func (d *oggDecoder) More() bool {
return !d.done
}
func (d *oggDecoder) Page() (hdr oggPageHeader, sd *oggSegmentDecoder, err error) {
if d.sd != nil {
for d.sd.More() {
err = d.sd.SkipSegment()
if err != nil {
return
}
}
}
sd = &oggSegmentDecoder{}
d.sd = sd
// Read header
err = binary.Read(d.r, binary.LittleEndian, &hdr)
if err != nil {
return
}
// Validate magic number
if string(hdr.MagicNumber[:]) != "OggS" {
err = ErrOggInvalidMagicNumber
return
}
// Save the given checksum to match later
sd.givenSum = hdr.Checksum
// Set checksum field to 0 before recalculating the checksum
hdr.Checksum = 0
sd.sum = &crc32Writer{}
// Write header to checksum
binary.Write(sd.sum, binary.LittleEndian, hdr)
// Write any future data read by the segment reader to the checksum as well
sd.r = io.TeeReader(d.r, sd.sum)
// Read the sizes of all page segments
segsizes := make([]byte, hdr.NumSegments)
sd.r.Read(segsizes)
// Whether to add to the last segment size: Whenever a segment length is
// specified as being 255, that means the next segment should be appended
// to it.
var add bool
for _, s := range segsizes {
if add {
sd.fullSegsizes[len(sd.fullSegsizes)-1] += int(s)
} else {
sd.fullSegsizes = append(sd.fullSegsizes, int(s))
}
add = s == 255
}
if hdr.HeaderType == FHeaderTypeEOS {
d.done = true
}
return
}
type oggSegmentDecoder struct {
dec *oggDecoder
r io.Reader
sum *crc32Writer
givenSum uint32
fullSegsizes []int
i int // segment index
done bool
}
func (d *oggSegmentDecoder) More() bool {
return !d.done
}
func (d *oggSegmentDecoder) SegmentSize() int {
return d.fullSegsizes[d.i]
}
func (d *oggSegmentDecoder) SkipSegment() error {
_, err := io.CopyN(io.Discard, d.r, int64(d.fullSegsizes[d.i]))
if err != nil {
d.done = true
return err
}
d.i++
if d.i == len(d.fullSegsizes) {
d.done = true
if d.sum.sum != d.givenSum {
return ErrOggInvalidChecksum
}
}
return nil
}
// Assumes buf to be exactly the right size (use SegmentSize() to get the size beforehand)
func (d *oggSegmentDecoder) ReadSegment(buf []byte) error {
if len(buf) != d.fullSegsizes[d.i] {
return ErrOggInvalidSegmentBufferSize
}
_, err := io.ReadFull(d.r, buf)
if err != nil {
d.done = true
return err
}
d.i++
if d.i == len(d.fullSegsizes) {
d.done = true
if d.sum.sum != d.givenSum {
return ErrOggInvalidChecksum
}
}
return nil
}