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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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83
main.go
View File

@ -2,6 +2,7 @@ package main
import ( import (
"bufio" "bufio"
"encoding/binary"
"errors" "errors"
"fmt" "fmt"
"io" "io"
@ -9,7 +10,7 @@ import (
"os" "os"
) )
const fname = "/home/rob/home-office/example.mp3" const fname = "/home/rob/share/home-office/example.mp3"
type ( type (
AudioVersionId int AudioVersionId int
@ -32,27 +33,71 @@ const (
LayerIndexI LayerIndexI
) )
var sampleRates = [5][16]uint32{ var (
{0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448, 0}, bitRates = [5][16]uint32{
{0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 0}, {0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448, 0},
{0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 0}, {0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 0},
{0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0}, {0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 0},
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0}, {0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0},
{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 { func (h header) AudioVersionId() AudioVersionId {
return AudioVersionId(((h >> 8) & 0x18) >> 3) return AudioVersionId((h >> 19) & 0x3)
} }
func (h header) LayerIndex() LayerIndex { func (h header) LayerIndex() LayerIndex {
return LayerIndex(((h >> 8) & 0x6) >> 1) return LayerIndex(((h >> 8) & 0x6) >> 1)
} }
func (h header) IsPrivate() bool { func (h header) IsProtected() bool {
return (h>>8)&1 == 1 return (h>>8)&1 == 1
} }
func (h header) SampleRate() uint32 { 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 var j int
switch h.AudioVersionId() { switch h.AudioVersionId() {
case AudioVersionMPEG1: case AudioVersionMPEG1:
@ -80,7 +125,7 @@ func (h header) SampleRate() uint32 {
} }
} }
k := ((h >> 20) & 0xf) k := ((h >> 20) & 0xf)
return sampleRates[j][k] return bitRates[j][k]
} }
func main() { func main() {
@ -103,12 +148,13 @@ func main() {
} }
header, err := newHeaderFromBytes(buf) header, err := newHeaderFromBytes(buf)
if err == nil { if header.IsValid() {
fmt.Printf("Got header: %08X, audio version: %d, layer index: %d\n", header, header.AudioVersionId(), header.LayerIndex()) 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++ i++
bufreader.Discard(3)
} }
} }
@ -116,13 +162,8 @@ func newHeaderFromBytes(buf []byte) (header, error) {
if len(buf) < 4 { if len(buf) < 4 {
return 0, errors.New("insufficient bytes") return 0, errors.New("insufficient bytes")
} }
if buf[0] != 0xFF || buf[1]&0xE0 != 0xE0 { // assume little-endian for now
return 0, errors.New("no header") return newHeader(binary.LittleEndian.Uint32(buf))
}
// always little-endian for now
n := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
return newHeader(n)
} }
// TODO use unsafe here? https://codereview.stackexchange.com/a/60161 // 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) { func TestAudioVersionId(t *testing.T) {
bytes := []byte{0xff, 0xe8, 0, 0} bytes := []byte{0xff, 0xe8, 0, 0}
h, err := newHeader(binary.LittleEndian.Uint32(bytes)) h, err := newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) require.NoError(t, err)
assert.Equal(t, AudioVersionReserved, h.AudioVersionId()) assert.Equal(t, AudioVersionReserved, h.AudioVersionId())
bytes = []byte{0xff, 0xf0, 0, 0} bytes = []byte{0xff, 0xf0, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes)) h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) require.NoError(t, err)
assert.Equal(t, AudioVersionMPEG2, h.AudioVersionId()) assert.Equal(t, AudioVersionMPEG2, h.AudioVersionId())
bytes = []byte{0xff, 0xff, 0, 0} bytes = []byte{0xff, 0xff, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes)) h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) require.NoError(t, err)
assert.Equal(t, AudioVersionMPEG1, h.AudioVersionId()) assert.Equal(t, AudioVersionMPEG1, h.AudioVersionId())
bytes = []byte{0xff, 0xe0, 0, 0} bytes = []byte{0xff, 0xe0, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes)) h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) require.NoError(t, err)
assert.Equal(t, AudioVersionMPEG25, h.AudioVersionId()) assert.Equal(t, AudioVersionMPEG25, h.AudioVersionId())
} }
func TestLayerIndex(t *testing.T) { // func TestLayerIndex(t *testing.T) {
bytes := []byte{0xff, 0xe2, 0, 0} // bytes := []byte{0xff, 0xe2, 0, 0}
h, err := newHeader(binary.LittleEndian.Uint32(bytes)) // h, err := newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) // require.NoError(t, err)
assert.Equal(t, LayerIndexIII, h.LayerIndex()) // assert.Equal(t, LayerIndexIII, h.LayerIndex())
bytes = []byte{0xff, 0xe4, 0, 0} // bytes = []byte{0xff, 0xe4, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes)) // h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) // require.NoError(t, err)
assert.Equal(t, LayerIndexII, h.LayerIndex()) // assert.Equal(t, LayerIndexII, h.LayerIndex())
bytes = []byte{0xff, 0xe6, 0, 0} // bytes = []byte{0xff, 0xe6, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes)) // h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) // require.NoError(t, err)
assert.Equal(t, LayerIndexI, h.LayerIndex()) // assert.Equal(t, LayerIndexI, h.LayerIndex())
} // }
func TestIsPrivate(t *testing.T) { // func TestIsProtected(t *testing.T) {
bytes := []byte{0xff, 0xe1, 0, 0} // bytes := []byte{0xff, 0xe1, 0, 0}
h, err := newHeader(binary.LittleEndian.Uint32(bytes)) // h, err := newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) // require.NoError(t, err)
assert.True(t, h.IsPrivate()) // assert.True(t, h.IsProtected())
bytes = []byte{0xff, 0xe0, 0, 0} // bytes = []byte{0xff, 0xe0, 0, 0}
h, err = newHeader(binary.LittleEndian.Uint32(bytes)) // h, err = newHeader(binary.BigEndian.Uint32(bytes))
require.NoError(t, err) // require.NoError(t, err)
assert.False(t, h.IsPrivate()) // assert.False(t, h.IsProtected())
} // }
func TestSampleRate(t *testing.T) { // func TestBitRate(t *testing.T) {
testCases := []struct { // testCases := []struct {
name string // name string
bytes []byte // bytes []byte
expSampleRate uint32 // expBitRate uint32
}{ // }{
{ // {
"empty header", // "empty header",
[]byte{0, 0, 0, 0}, // []byte{0, 0, 0, 0},
0, // 0,
}, // },
{ // {
"MPEG1 LayerI 32kbps", // "MPEG1 LayerI 32kbps",
[]byte{0xff, 0xfe, 0x10, 0}, // []byte{0xff, 0xfe, 0x10, 0},
32, // 32,
}, // },
{ // {
"MPEG1 LayerI 448kbps", // "MPEG1 LayerI 448kbps",
[]byte{0xff, 0xfe, 0xe0, 0}, // []byte{0xff, 0xfe, 0xe0, 0},
448, // 448,
}, // },
{ // {
"MPEG1 LayerII 32kbps", // "MPEG1 LayerII 32kbps",
[]byte{0xff, 0xfc, 0x10, 0}, // []byte{0xff, 0xfc, 0x10, 0},
32, // 32,
}, // },
{ // {
"MPEG1 LayerII 448kbps", // "MPEG1 LayerII 448kbps",
[]byte{0xff, 0xfc, 0xe0, 0}, // []byte{0xff, 0xfc, 0xe0, 0},
384, // 384,
}, // },
{ // {
"MPEG1 LayerIII 32kbps", // "MPEG1 LayerIII 32kbps",
[]byte{0xff, 0xfa, 0x10, 0}, // []byte{0xff, 0xfa, 0x10, 0},
32, // 32,
}, // },
{ // {
"MPEG1 LayerIII 128kbps", // "MPEG1 LayerIII 128kbps",
[]byte{0xff, 0xfa, 0x90, 0}, // []byte{0xff, 0xfa, 0x90, 0},
128, // 128,
}, // },
{ // {
"MPEG1 LayerIII 160kbps", // "MPEG1 LayerIII 160kbps",
[]byte{0xff, 0xfa, 0xa0, 0}, // []byte{0xff, 0xfa, 0xa0, 0},
160, // 160,
}, // },
{ // {
"MPEG1 LayerIII 320kbps", // "MPEG1 LayerIII 192kbps",
[]byte{0xff, 0xfa, 0xe0, 0x0}, // []byte{0xff, 0xfb, 0xb0, 0},
320, // 192,
}, // },
{ // {
"MPEG1 LayerIII reserved", // "MPEG1 LayerIII 320kbps",
[]byte{0xff, 0xfa, 0xf0, 0x0}, // []byte{0xff, 0xfa, 0xe0, 0},
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 { // for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) { // t.Run(tc.name, func(t *testing.T) {
h, err := newHeader(binary.LittleEndian.Uint32(tc.bytes)) // h, err := newHeader(binary.BigEndian.Uint32(tc.bytes))
require.NoError(t, err) // require.NoError(t, err)
assert.Equal(t, tc.expSampleRate, h.SampleRate()) // 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()))
// })
// }
// }