wip: nothing working

This commit is contained in:
Rob Watson 2021-01-25 19:35:18 +01:00
parent 67be7684dc
commit f16a5c99c8
4 changed files with 89 additions and 9 deletions

2
go.mod
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@ -1,3 +1,5 @@
module git.netflux.io/rob/avframes
go 1.15
require github.com/stretchr/testify v1.7.0

11
go.sum Normal file
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@ -0,0 +1,11 @@
github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

50
main.go
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@ -2,16 +2,32 @@ package main
import (
"bufio"
"errors"
"fmt"
"io"
"log"
"os"
)
const fname = "/home/rob/Desktop/example.mp3"
const fname = "/home/rob/home-office/example.mp3"
const syncHeader1 = 0xFF
const syncHeader2 = 0xFE
const (
maskSync = 0b11111111111000000000000000000000
maskVersion = 0b00000000000110000000000000000000
maskLayer = 0b00000000000001100000000000000000
maskProtection = 0b00000000000000010000000000000000
maskBitrate = 0b00000000000000001111000000000000
maskSamplerate = 0b00000000000000000000110000000000
maskPadding = 0b00000000000000000000001000000000
maskPrivate = 0b00000000000000000000000100000000
maskChannelMode = 0b00000000000000000000000011000000
maskExtension = 0b00000000000000000000000000110000
maskCopyright = 0b00000000000000000000000000001000
maskOriginal = 0b00000000000000000000000000000100
maskEmphasis = 0b00000000000000000000000000000011
)
type header uint32
func main() {
f, err := os.Open(fname)
@ -26,18 +42,34 @@ func main() {
for {
_, err := io.ReadFull(bufreader, buf)
if err != nil {
if err == io.EOF {
break
}
log.Fatal(err)
}
if parseBytes(buf) {
fmt.Printf("Got possible header %X at %d\n", buf, i)
}
header, err := newHeader(buf)
if err == nil {
fmt.Printf("Got header: %08X\n", header)
}
i++
bufreader.UnreadByte()
bufreader.Discard(3)
}
}
func parseBytes(buf []byte) bool {
return buf[0]&syncHeader1 == syncHeader1 || buf[0]&syncHeader2 == syncHeader2
// TODO use unsafe here? https://codereview.stackexchange.com/a/60161
func newHeader(buf []byte) (header, error) {
if len(buf) < 4 {
return 0, errors.New("insufficient bytes")
}
if buf[0] != 0xFF || buf[1]&0xE0 != 0xE0 {
return 0, errors.New("no header")
}
// always little-endian for now
n := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
return header(n), nil
}

35
main_test.go Normal file
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@ -0,0 +1,35 @@
package main
import (
"fmt"
"testing"
"github.com/stretchr/testify/assert"
)
func TestMain(t *testing.T) {
testCases := []struct {
input []byte
expectedError string
}{
{
input: []byte{0, 0, 0, 0},
expectedError: "no header",
},
{
input: []byte{0, 0, 0, 1},
expectedError: "no header",
},
{
input: []byte{0xff, 0xfe, 0, 0}, // wrong
expectedError: "",
},
}
for _, tc := range testCases {
t.Run(fmt.Sprintf("Header %08b", tc.input), func(t *testing.T) {
_, err := newHeader(tc.input)
assert.EqualError(t, err, tc.expectedError)
})
}
}