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avframes
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wip: about to refactor to use byte slice

This commit is contained in:
Rob Watson 2021-01-27 06:22:17 +01:00
parent f8888ef614
commit e99b2923c1
2 changed files with 262 additions and 114 deletions
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73
main.go
View File

@ -2,6 +2,7 @@ package main
import (
"bufio"
"encoding/binary"
"errors"
"fmt"
"io"
@ -9,7 +10,7 @@ import (
"os"
)
const fname = "/home/rob/home-office/example.mp3"
const fname = "/home/rob/share/home-office/example.mp3"
type (
AudioVersionId int
@ -32,7 +33,8 @@ const (
LayerIndexI
)
var sampleRates = [5][16]uint32{
var (
bitRates = [5][16]uint32{
{0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448, 0},
{0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 0},
{0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 0},
@ -40,19 +42,62 @@ var sampleRates = [5][16]uint32{
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0},
}
sampleRates = [4][4]uint32{
{11025, 12000, 8000, 0},
{0, 0, 0, 0},
{22050, 24000, 16000, 0},
{44100, 48000, 32000, 0},
}
samplesPerFrame = [4][4]uint32{
{0, 384, 1152, 576},
{0, 0, 0, 0},
{384, 1152, 576},
{384, 1152, 1152},
}
)
// TODO tests
func (h header) HasSyncWord() bool {
return (h>>21)&0x7ff == 0x7ff
}
func (h header) AudioVersionId() AudioVersionId {
return AudioVersionId(((h >> 8) & 0x18) >> 3)
return AudioVersionId((h >> 19) & 0x3)
}
func (h header) LayerIndex() LayerIndex {
return LayerIndex(((h >> 8) & 0x6) >> 1)
}
func (h header) IsPrivate() bool {
func (h header) IsProtected() bool {
return (h>>8)&1 == 1
}
func (h header) SampleRate() uint32 {
i := h.AudioVersionId()
j := (h >> 18) & 0xb11
return sampleRates[i][j]
}
func (h header) IsValid() bool {
if !h.HasSyncWord() {
return false
}
if h.AudioVersionId() == AudioVersionReserved {
return false
}
if h.LayerIndex() == LayerIndexReserved {
return false
}
if h.BitRate() == 0 {
return false
}
return true
}
func (h header) BitRate() uint32 {
var j int
switch h.AudioVersionId() {
case AudioVersionMPEG1:
@ -80,7 +125,7 @@ func (h header) SampleRate() uint32 {
}
}
k := ((h >> 20) & 0xf)
return sampleRates[j][k]
return bitRates[j][k]
}
func main() {
@ -103,12 +148,13 @@ func main() {
}
header, err := newHeaderFromBytes(buf)
if err == nil {
fmt.Printf("Got header: %08X, audio version: %d, layer index: %d\n", header, header.AudioVersionId(), header.LayerIndex())
if header.IsValid() {
fmt.Printf("%+v\n", buf)
fmt.Printf("Got header: %032b, audio version: %d, layer index: %d, bitrate: %d\n", header, header.AudioVersionId(), header.LayerIndex(), header.BitRate())
} else {
bufreader.Discard(3)
}
i++
bufreader.Discard(3)
}
}
@ -116,13 +162,8 @@ func newHeaderFromBytes(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 newHeader(n)
// assume little-endian for now
return newHeader(binary.LittleEndian.Uint32(buf))
}
// TODO use unsafe here? https://codereview.stackexchange.com/a/60161

293
main_test.go
View File

@ -10,118 +10,225 @@ import (
func TestAudioVersionId(t *testing.T) {
bytes := []byte{0xff, 0xe8, 0, 0}
h, err := newHeader(binary.LittleEndian.Uint32(bytes))
h, err := newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err)
assert.Equal(t, AudioVersionReserved, h.AudioVersionId())
bytes = []byte{0xff, 0xf0, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes))
h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err)
assert.Equal(t, AudioVersionMPEG2, h.AudioVersionId())
bytes = []byte{0xff, 0xff, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes))
h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err)
assert.Equal(t, AudioVersionMPEG1, h.AudioVersionId())
bytes = []byte{0xff, 0xe0, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes))
h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err)
assert.Equal(t, AudioVersionMPEG25, h.AudioVersionId())
}
func TestLayerIndex(t *testing.T) {
bytes := []byte{0xff, 0xe2, 0, 0}
h, err := newHeader(binary.LittleEndian.Uint32(bytes))
require.NoError(t, err)
assert.Equal(t, LayerIndexIII, h.LayerIndex())
// func TestLayerIndex(t *testing.T) {
// bytes := []byte{0xff, 0xe2, 0, 0}
// h, err := newHeader(binary.BigEndian.Uint32(bytes))
// require.NoError(t, err)
// assert.Equal(t, LayerIndexIII, h.LayerIndex())
bytes = []byte{0xff, 0xe4, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes))
require.NoError(t, err)
assert.Equal(t, LayerIndexII, h.LayerIndex())
// bytes = []byte{0xff, 0xe4, 0, 0}
// h, err = newHeader(binary.BigEndian.Uint32(bytes))
// require.NoError(t, err)
// assert.Equal(t, LayerIndexII, h.LayerIndex())
bytes = []byte{0xff, 0xe6, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes))
require.NoError(t, err)
assert.Equal(t, LayerIndexI, h.LayerIndex())
}
// bytes = []byte{0xff, 0xe6, 0, 0}
// h, err = newHeader(binary.BigEndian.Uint32(bytes))
// require.NoError(t, err)
// assert.Equal(t, LayerIndexI, h.LayerIndex())
// }
func TestIsPrivate(t *testing.T) {
bytes := []byte{0xff, 0xe1, 0, 0}
h, err := newHeader(binary.LittleEndian.Uint32(bytes))
require.NoError(t, err)
assert.True(t, h.IsPrivate())
// func TestIsProtected(t *testing.T) {
// bytes := []byte{0xff, 0xe1, 0, 0}
// h, err := newHeader(binary.BigEndian.Uint32(bytes))
// require.NoError(t, err)
// assert.True(t, h.IsProtected())
bytes = []byte{0xff, 0xe0, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes))
require.NoError(t, err)
assert.False(t, h.IsPrivate())
}
// bytes = []byte{0xff, 0xe0, 0, 0}
// h, err = newHeader(binary.BigEndian.Uint32(bytes))
// require.NoError(t, err)
// assert.False(t, h.IsProtected())
// }
func TestSampleRate(t *testing.T) {
testCases := []struct {
name string
bytes []byte
expSampleRate uint32
}{
{
"empty header",
[]byte{0, 0, 0, 0},
0,
},
{
"MPEG1 LayerI 32kbps",
[]byte{0xff, 0xfe, 0x10, 0},
32,
},
{
"MPEG1 LayerI 448kbps",
[]byte{0xff, 0xfe, 0xe0, 0},
448,
},
{
"MPEG1 LayerII 32kbps",
[]byte{0xff, 0xfc, 0x10, 0},
32,
},
{
"MPEG1 LayerII 448kbps",
[]byte{0xff, 0xfc, 0xe0, 0},
384,
},
{
"MPEG1 LayerIII 32kbps",
[]byte{0xff, 0xfa, 0x10, 0},
32,
},
{
"MPEG1 LayerIII 128kbps",
[]byte{0xff, 0xfa, 0x90, 0},
128,
},
{
"MPEG1 LayerIII 160kbps",
[]byte{0xff, 0xfa, 0xa0, 0},
160,
},
{
"MPEG1 LayerIII 320kbps",
[]byte{0xff, 0xfa, 0xe0, 0x0},
320,
},
{
"MPEG1 LayerIII reserved",
[]byte{0xff, 0xfa, 0xf0, 0x0},
0,
},
}
// func TestBitRate(t *testing.T) {
// testCases := []struct {
// name string
// bytes []byte
// expBitRate uint32
// }{
// {
// "empty header",
// []byte{0, 0, 0, 0},
// 0,
// },
// {
// "MPEG1 LayerI 32kbps",
// []byte{0xff, 0xfe, 0x10, 0},
// 32,
// },
// {
// "MPEG1 LayerI 448kbps",
// []byte{0xff, 0xfe, 0xe0, 0},
// 448,
// },
// {
// "MPEG1 LayerII 32kbps",
// []byte{0xff, 0xfc, 0x10, 0},
// 32,
// },
// {
// "MPEG1 LayerII 448kbps",
// []byte{0xff, 0xfc, 0xe0, 0},
// 384,
// },
// {
// "MPEG1 LayerIII 32kbps",
// []byte{0xff, 0xfa, 0x10, 0},
// 32,
// },
// {
// "MPEG1 LayerIII 128kbps",
// []byte{0xff, 0xfa, 0x90, 0},
// 128,
// },
// {
// "MPEG1 LayerIII 160kbps",
// []byte{0xff, 0xfa, 0xa0, 0},
// 160,
// },
// {
// "MPEG1 LayerIII 192kbps",
// []byte{0xff, 0xfb, 0xb0, 0},
// 192,
// },
// {
// "MPEG1 LayerIII 320kbps",
// []byte{0xff, 0xfa, 0xe0, 0},
// 320,
// },
// {
// "MPEG1 LayerIII reserved",
// []byte{0xff, 0xfa, 0xf0, 0},
// 0,
// },
// {
// "MPEG2 LayerI 32kbps",
// []byte{0xff, 0xf6, 0x10, 0},
// 32,
// },
// {
// "MPEG2 LayerI 256",
// []byte{0xff, 0xf6, 0xe0, 0},
// 256,
// },
// {
// "MPEG2 LayerII 32kbps",
// []byte{0xff, 0xf4, 0x10, 0},
// 8,
// },
// {
// "MPEG2 LayerII 160kbps",
// []byte{0xff, 0xf4, 0xe0, 0},
// 160,
// },
// {
// "MPEG2 LayerIII 32kbps",
// []byte{0xff, 0xf2, 0x10, 0},
// 8,
// },
// {
// "MPEG2 LayerIII 160kbps",
// []byte{0xff, 0xf2, 0xe0, 0},
// 160,
// },
// {
// "MPEG25 LayerI 32kbps",
// []byte{0xff, 0xe6, 0x10, 0},
// 32,
// },
// {
// "MPEG25 LayerI 256",
// []byte{0xff, 0xe6, 0xe0, 0},
// 256,
// },
// {
// "MPEG25 LayerII 32kbps",
// []byte{0xff, 0xe4, 0x10, 0},
// 8,
// },
// {
// "MPEG25 LayerII 160kbps",
// []byte{0xff, 0xe4, 0xe0, 0},
// 160,
// },
// {
// "MPEG25 LayerIII 32kbps",
// []byte{0xff, 0xe2, 0x10, 0},
// 8,
// },
// {
// "MPEG25 LayerIII 160kbps",
// []byte{0xff, 0xe2, 0xe0, 0},
// 160,
// },
// {
// "full header",
// []byte{1, 1, 1, 1},
// 0,
// },
// }
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
h, err := newHeader(binary.LittleEndian.Uint32(tc.bytes))
require.NoError(t, err)
assert.Equal(t, tc.expSampleRate, h.SampleRate())
})
}
}
// for _, tc := range testCases {
// t.Run(tc.name, func(t *testing.T) {
// h, err := newHeader(binary.BigEndian.Uint32(tc.bytes))
// require.NoError(t, err)
// assert.Equal(t, tc.expBitRate, h.BitRate())
// })
// }
// }
// func TestSampleRate(t *testing.T) {
// testCases := []struct {
// name string
// bytes []byte
// expSampleRate uint32
// }{
// {
// "MPEG1 44.1k",
// []byte{0xff, 0xfa, 0x90, 0},
// 44100,
// },
// {
// "MPEG1 48k",
// []byte{0xff, 0xfa, 0x94, 0},
// 48000,
// },
// {
// "MPEG1 32k",
// []byte{0xff, 0xfa, 0x98, 0},
// 32000,
// },
// {
// "MPEG1 Reserved",
// []byte{0xff, 0xfa, 0x9c, 0},
// 32000,
// },
// }
// for _, tc := range testCases {
// t.Run(tc.name, func(t *testing.T) {
// h, err := newHeader(binary.BigEndian.Uint32(tc.bytes))
// require.NoError(t, err)
// assert.Equal(t, int(tc.expSampleRate), int(h.SampleRate()))
// })
// }
// }