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audio/mp3: Move Read_Header to Go

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This commit is contained in:
Hajime Hoshi 2017-06-17 00:08:47 +09:00
parent f6e7e3601f
commit e41c0d3514
3 changed files with 94 additions and 93 deletions
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92
audio/mp3/pdmp3.c
View File

@ -11,7 +11,6 @@
#include <unistd.h>
#include <stdlib.h>
#define C_SYNC 0xffe00000
#define C_EOF 0xffffffff
#define C_PI 3.14159265358979323846
#define C_INV_SQRT_2 0.70710678118654752440
@ -242,97 +241,6 @@ int Read_Frame(void){
return(OK);
}
static bool is_header(unsigned header) {
/* Are the high 11 bits the syncword(0xffe)? */
if ((header & C_SYNC) != C_SYNC) {
return false;
}
// Bitrate must not be 15.
if ((header & (0xf<<12)) == 0xf<<12) {
return false;
}
// Sample Frequency must not be 3.
if ((header & (3<<10)) == 3<<10) {
return false;
}
return true;
}
/**Description: Scans bitstream for syncword until we find it or EOF. The
syncword must be byte-aligned. It then reads and parses audio header.
* Parameters: None
* Return value: OK or ERROR if the syncword can't be found,or the header
* contains impossible values.
* Author: Krister Lagerström(krister@kmlager.com) **/
static int Read_Header(void) {
unsigned b1,b2,b3,b4,header;
/* Get the next four bytes from the bitstream */
b1 = Get_Byte();
b2 = Get_Byte();
b3 = Get_Byte();
b4 = Get_Byte();
/* If we got an End Of File condition we're done */
if((b1==C_EOF)||(b2==C_EOF)||(b3==C_EOF)||(b4==C_EOF))
return(ERROR);
header =(b1 << 24) |(b2 << 16) |(b3 << 8) |(b4 << 0);
while(!is_header(header)) {
/* No,so scan the bitstream one byte at a time until we find it or EOF */
/* Shift the values one byte to the left */
b1 = b2;
b2 = b3;
b3 = b4;
/* Get one new byte from the bitstream */
b4 = Get_Byte();
/* If we got an End Of File condition we're done */
if(b4 == C_EOF) return(ERROR);
/* Make up the new header */
header = (b1 << 24) | (b2 << 16) | (b3 << 8) | (b4 << 0);
} /* while... */
/* If we get here we've found the sync word,and can decode the header
* which is in the low 20 bits of the 32-bit sync+header word. */
/* Decode the header */
g_frame_header.id =(header & 0x00180000) >> 19;
g_frame_header.layer =(header & 0x00060000) >> 17;
g_frame_header.protection_bit =(header & 0x00010000) >> 16;
g_frame_header.bitrate_index =(header & 0x0000f000) >> 12;
g_frame_header.sampling_frequency =(header & 0x00000c00) >> 10;
g_frame_header.padding_bit =(header & 0x00000200) >> 9;
g_frame_header.private_bit =(header & 0x00000100) >> 8;
g_frame_header.mode =(header & 0x000000c0) >> 6;
g_frame_header.mode_extension =(header & 0x00000030) >> 4;
g_frame_header.copyright =(header & 0x00000008) >> 3;
g_frame_header.original_or_copy =(header & 0x00000004) >> 2;
g_frame_header.emphasis =(header & 0x00000003) >> 0;
/* Check for invalid values and impossible combinations */
if(g_frame_header.id != 3) {
ERR("ID must be 3\nHeader word is 0x%08x at file pos %d\n",header,Get_Filepos());
return(ERROR);
}
if(g_frame_header.bitrate_index == 0) {
ERR("Free bitrate format NIY!\nHeader word is 0x%08x at file pos %d\n",header,Get_Filepos());
exit(1);
}
if(g_frame_header.bitrate_index == 15) {
ERR("bitrate_index = 15 is invalid!\nHeader word is 0x%08x at file pos %d\n",header,Get_Filepos());
return(ERROR);
}
if(g_frame_header.sampling_frequency == 3) {
ERR("sampling_frequency = 3 is invalid!\n");
ERR("Header word is 0x%08x at file pos %d\n",header,Get_Filepos());
return(ERROR);
}
if(g_frame_header.layer == 0) {
ERR("layer = 0 is invalid!\n");
ERR("Header word is 0x%08x at file pos %d\n",header,
Get_Filepos());
return(ERROR);
}
g_frame_header.layer = 4 - g_frame_header.layer;
/* DBG("Header = 0x%08x\n",header); */
return(OK); /* Done */
}
/**Description: TBD
* Parameters: TBD
* Return value: TBD

2
audio/mp3/pdmp3.h
View File

@ -96,7 +96,7 @@ int Set_Main_Pos(unsigned bit_pos);
int Read_Main_L3(void);
int Read_Audio_L3(void);
static int Read_Header(void);
int Read_Header(void);
void L3_Requantize(unsigned gr,unsigned ch);
void L3_Reorder(unsigned gr,unsigned ch);

93
audio/mp3/read.go
View File

@ -23,6 +23,99 @@ package mp3
// extern t_mpeg1_header g_frame_header;
import "C"
import (
"fmt"
)
func isHeader(header uint32) bool {
const C_SYNC = 0xffe00000
if (header & C_SYNC) != C_SYNC {
return false
}
// Bitrate must not be 15.
if (header & (0xf << 12)) == 0xf<<12 {
return false
}
// Sample Frequency must not be 3.
if (header & (3 << 10)) == 3<<10 {
return false
}
return true
}
//export Read_Header
func Read_Header() C.int {
/* Get the next four bytes from the bitstream */
b1 := uint32(Get_Byte())
b2 := uint32(Get_Byte())
b3 := uint32(Get_Byte())
b4 := uint32(Get_Byte())
/* If we got an End Of File condition we're done */
if (b1 == eof) || (b2 == eof) || (b3 == eof) || (b4 == eof) {
return C.ERROR
}
header := (b1 << 24) | (b2 << 16) | (b3 << 8) | (b4 << 0)
for !isHeader(uint32(header)) {
/* No,so scan the bitstream one byte at a time until we find it or EOF */
/* Shift the values one byte to the left */
b1 = b2
b2 = b3
b3 = b4
/* Get one new byte from the bitstream */
b4 = uint32(Get_Byte())
/* If we got an End Of File condition we're done */
if b4 == eof {
return C.ERROR
}
/* Make up the new header */
header = (b1 << 24) | (b2 << 16) | (b3 << 8) | (b4 << 0)
} /* while... */
/* If we get here we've found the sync word,and can decode the header
* which is in the low 20 bits of the 32-bit sync+header word. */
/* Decode the header */
C.g_frame_header.id = C.uint((header & 0x00180000) >> 19)
C.g_frame_header.layer = C.t_mpeg1_layer((header & 0x00060000) >> 17)
C.g_frame_header.protection_bit = C.uint((header & 0x00010000) >> 16)
C.g_frame_header.bitrate_index = C.uint((header & 0x0000f000) >> 12)
C.g_frame_header.sampling_frequency = C.uint((header & 0x00000c00) >> 10)
C.g_frame_header.padding_bit = C.uint((header & 0x00000200) >> 9)
C.g_frame_header.private_bit = C.uint((header & 0x00000100) >> 8)
C.g_frame_header.mode = C.t_mpeg1_mode((header & 0x000000c0) >> 6)
C.g_frame_header.mode_extension = C.uint((header & 0x00000030) >> 4)
C.g_frame_header.copyright = C.uint((header & 0x00000008) >> 3)
C.g_frame_header.original_or_copy = C.uint((header & 0x00000004) >> 2)
C.g_frame_header.emphasis = C.uint((header & 0x00000003) >> 0)
/* Check for invalid values and impossible combinations */
if C.g_frame_header.id != 3 {
g_error = fmt.Errorf("mp3: ID must be 3\nHeader word is 0x%08x at file pos %d",
header, C.Get_Filepos())
return C.ERROR
}
if C.g_frame_header.bitrate_index == 0 {
g_error = fmt.Errorf("mp3: Free bitrate format NIY!\nHeader word is 0x%08x at file pos %d",
header, Get_Filepos())
return C.ERROR
//exit(1);
}
if C.g_frame_header.bitrate_index == 15 {
g_error = fmt.Errorf("mp3: bitrate_index = 15 is invalid!\nHeader word is 0x%08x at file pos %d",
header, Get_Filepos())
return C.ERROR
}
if C.g_frame_header.sampling_frequency == 3 {
g_error = fmt.Errorf("mp3: sampling_frequency = 3 is invalid! Header word is 0x%08x at file pos %d",
header, Get_Filepos())
return C.ERROR
}
if C.g_frame_header.layer == 0 {
g_error = fmt.Errorf("mp3: layer = 0 is invalid! Header word is 0x%08x at file pos %d",
header, Get_Filepos())
return C.ERROR
}
C.g_frame_header.layer = 4 - C.g_frame_header.layer
return C.OK
}
func readHuffman(part_2_start, gr, ch int) error {
/* Check that there is any data to decode. If not,zero the array. */
if C.g_side_info.part2_3_length[gr][ch] == 0 {