ebiten/audio/mp3/maindata.go
2017-06-14 11:07:08 +09:00

267 lines
8.3 KiB
Go

// Copyright 2017 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !js
package mp3
// #include "pdmp3.h"
//
// extern t_mpeg1_main_data g_main_data;
// extern t_mpeg1_header g_frame_header;
// extern t_mpeg1_side_info g_side_info;
import "C"
import (
"fmt"
)
var mpeg1_scalefac_sizes = [16][2]int{
{0, 0}, {0, 1}, {0, 2}, {0, 3}, {3, 0}, {1, 1}, {1, 2}, {1, 3},
{2, 1}, {2, 2}, {2, 3}, {3, 1}, {3, 2}, {3, 3}, {4, 2}, {4, 3},
}
//export Read_Main_L3
func Read_Main_L3() C.int {
/* Number of channels(1 for mono and 2 for stereo) */
nch := 2
if C.g_frame_header.mode == C.mpeg1_mode_single_channel {
nch = 1
}
/* Calculate header audio data size */
framesize := (144*
g_mpeg1_bitrates[C.g_frame_header.layer-1][C.g_frame_header.bitrate_index])/
g_sampling_frequency[C.g_frame_header.sampling_frequency] +
int(C.g_frame_header.padding_bit)
if framesize > 2000 {
g_error = fmt.Errorf("mp3: framesize = %d", framesize)
return C.ERROR
}
/* Sideinfo is 17 bytes for one channel and 32 bytes for two */
sideinfo_size := 32
if nch == 1 {
sideinfo_size = 17
}
/* Main data size is the rest of the frame,including ancillary data */
main_data_size := framesize - sideinfo_size - 4 /* sync+header */
/* CRC is 2 bytes */
if C.g_frame_header.protection_bit == 0 {
main_data_size -= 2
}
/* Assemble main data buffer with data from this frame and the previous
* two frames. main_data_begin indicates how many bytes from previous
* frames that should be used. This buffer is later accessed by the
* getMainBits function in the same way as the side info is.
*/
if getMainData(main_data_size, int(C.g_side_info.main_data_begin)) != C.OK {
return C.ERROR /* This could be due to not enough data in reservoir */
}
for gr := 0; gr < 2; gr++ {
for ch := 0; ch < nch; ch++ {
part_2_start := Get_Main_Pos()
/* Number of bits in the bitstream for the bands */
slen1 := mpeg1_scalefac_sizes[C.g_side_info.scalefac_compress[gr][ch]][0]
slen2 := mpeg1_scalefac_sizes[C.g_side_info.scalefac_compress[gr][ch]][1]
if (C.g_side_info.win_switch_flag[gr][ch] != 0) && (C.g_side_info.block_type[gr][ch] == 2) {
if C.g_side_info.mixed_block_flag[gr][ch] != 0 {
for sfb := 0; sfb < 8; sfb++ {
C.g_main_data.scalefac_l[gr][ch][sfb] = C.uint(getMainBits(slen1))
}
for sfb := 3; sfb < 12; sfb++ {
/*slen1 for band 3-5,slen2 for 6-11*/
nbits := slen2
if sfb < 6 {
nbits = slen1
}
for win := 0; win < 3; win++ {
C.g_main_data.scalefac_s[gr][ch][sfb][win] = C.uint(getMainBits(nbits))
}
}
} else {
for sfb := 0; sfb < 12; sfb++ {
/*slen1 for band 3-5,slen2 for 6-11*/
nbits := slen2
if sfb < 6 {
nbits = slen1
}
for win := 0; win < 3; win++ {
C.g_main_data.scalefac_s[gr][ch][sfb][win] = C.uint(getMainBits(nbits))
}
}
}
} else { /* block_type == 0 if winswitch == 0 */
/* Scale factor bands 0-5 */
if (C.g_side_info.scfsi[ch][0] == 0) || (gr == 0) {
for sfb := 0; sfb < 6; sfb++ {
C.g_main_data.scalefac_l[gr][ch][sfb] = C.uint(getMainBits(slen1))
}
} else if (C.g_side_info.scfsi[ch][0] == 1) && (gr == 1) {
/* Copy scalefactors from granule 0 to granule 1 */
for sfb := 0; sfb < 6; sfb++ {
C.g_main_data.scalefac_l[1][ch][sfb] = C.g_main_data.scalefac_l[0][ch][sfb]
}
}
/* Scale factor bands 6-10 */
if (C.g_side_info.scfsi[ch][1] == 0) || (gr == 0) {
for sfb := 6; sfb < 11; sfb++ {
C.g_main_data.scalefac_l[gr][ch][sfb] = C.uint(getMainBits(slen1))
}
} else if (C.g_side_info.scfsi[ch][1] == 1) && (gr == 1) {
/* Copy scalefactors from granule 0 to granule 1 */
for sfb := 6; sfb < 11; sfb++ {
C.g_main_data.scalefac_l[1][ch][sfb] = C.g_main_data.scalefac_l[0][ch][sfb]
}
}
/* Scale factor bands 11-15 */
if (C.g_side_info.scfsi[ch][2] == 0) || (gr == 0) {
for sfb := 11; sfb < 16; sfb++ {
C.g_main_data.scalefac_l[gr][ch][sfb] = C.uint(getMainBits(slen2))
}
} else if (C.g_side_info.scfsi[ch][2] == 1) && (gr == 1) {
/* Copy scalefactors from granule 0 to granule 1 */
for sfb := 11; sfb < 16; sfb++ {
C.g_main_data.scalefac_l[1][ch][sfb] = C.uint(C.g_main_data.scalefac_l[0][ch][sfb])
}
}
/* Scale factor bands 16-20 */
if (C.g_side_info.scfsi[ch][3] == 0) || (gr == 0) {
for sfb := 16; sfb < 21; sfb++ {
C.g_main_data.scalefac_l[gr][ch][sfb] = C.uint(getMainBits(slen2))
}
} else if (C.g_side_info.scfsi[ch][3] == 1) && (gr == 1) {
/* Copy scalefactors from granule 0 to granule 1 */
for sfb := 16; sfb < 21; sfb++ {
C.g_main_data.scalefac_l[1][ch][sfb] = C.g_main_data.scalefac_l[0][ch][sfb]
}
}
}
/* Read Huffman coded data. Skip stuffing bits. */
C.Read_Huffman(part_2_start, C.uint(gr), C.uint(ch))
}
}
/* The ancillary data is stored here,but we ignore it. */
return C.OK
}
type mainDataBytes struct {
// Large static data
vec [2 * 1024]int
// Pointer into the reservoir
ptr []int
// Index into the current byte(0-7)
idx int
// Number of bytes in reservoir(0-1024)
top int
pos int
}
var theMainDataBytes mainDataBytes
func getMainData(size int, begin int) int {
if size > 1500 {
g_error = fmt.Errorf("size = %d", size)
}
/* Check that there's data available from previous frames if needed */
if int(begin) > theMainDataBytes.top {
// No,there is not,so we skip decoding this frame,but we have to
// read the main_data bits from the bitstream in case they are needed
// for decoding the next frame.
b, err := getBytes(size)
if err != nil {
g_error = err
return C.ERROR
}
copy(theMainDataBytes.vec[theMainDataBytes.top:], b)
/* Set up pointers */
theMainDataBytes.ptr = theMainDataBytes.vec[0:]
theMainDataBytes.pos = 0
theMainDataBytes.idx = 0
theMainDataBytes.top += size
return C.ERROR
}
/* Copy data from previous frames */
for i := 0; i < begin; i++ {
theMainDataBytes.vec[i] = theMainDataBytes.vec[theMainDataBytes.top-begin+i]
}
/* Read the main_data from file */
b, err := getBytes(int(size))
if err != nil {
g_error = err
return C.ERROR
}
copy(theMainDataBytes.vec[begin:], b)
/* Set up pointers */
theMainDataBytes.ptr = theMainDataBytes.vec[0:]
theMainDataBytes.pos = 0
theMainDataBytes.idx = 0
theMainDataBytes.top = begin + size
return C.OK
}
func getMainBit() int {
tmp := uint(theMainDataBytes.ptr[0]) >> (7 - uint(theMainDataBytes.idx))
tmp &= 0x01
theMainDataBytes.ptr = theMainDataBytes.ptr[(theMainDataBytes.idx+1)>>3:]
theMainDataBytes.pos += (theMainDataBytes.idx + 1) >> 3
theMainDataBytes.idx = (theMainDataBytes.idx + 1) & 0x07
return int(tmp)
}
func getMainBits(num int) int {
if num == 0 {
return 0
}
/* Form a word of the next four bytes */
b := make([]int, 4)
for i := range b {
if len(theMainDataBytes.ptr) > i {
b[i] = theMainDataBytes.ptr[i]
}
}
tmp := (uint32(b[0]) << 24) | (uint32(b[1]) << 16) | (uint32(b[2]) << 8) | (uint32(b[3]) << 0)
/* Remove bits already used */
tmp = tmp << uint(theMainDataBytes.idx)
/* Remove bits after the desired bits */
tmp = tmp >> (32 - uint(num))
/* Update pointers */
theMainDataBytes.ptr = theMainDataBytes.ptr[(theMainDataBytes.idx+int(num))>>3:]
theMainDataBytes.pos += (theMainDataBytes.idx + num) >> 3
theMainDataBytes.idx = (theMainDataBytes.idx + num) & 0x07
/* Done */
return int(tmp)
}
//export Get_Main_Pos
func Get_Main_Pos() C.unsigned {
pos := theMainDataBytes.pos
pos *= 8 /* Multiply by 8 to get number of bits */
pos += theMainDataBytes.idx /* Add current bit index */
return C.unsigned(pos)
}
//export Set_Main_Pos
func Set_Main_Pos(bit_pos C.unsigned) C.int {
theMainDataBytes.ptr = theMainDataBytes.vec[bit_pos>>3:]
theMainDataBytes.pos = int(bit_pos) >> 3
theMainDataBytes.idx = int(bit_pos) & 0x7
return C.OK
}