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Minor ADPCM quality enhancements

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@1603 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Mark Spencer
2003-10-02 23:17:32 +00:00
parent e4b8d32001
commit f7f5b56b0a
2 changed files with 112 additions and 48 deletions
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69
formats/format_vox.c
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@@ -33,6 +33,7 @@
#endif
#define BUF_SIZE 80 /* 160 samples */
#define BUF_SHIFT 5
struct ast_filestream {
void *reserved[AST_RESERVED_POINTERS];
@@ -41,11 +42,13 @@ struct ast_filestream {
struct ast_frame fr; /* Frame information */
char waste[AST_FRIENDLY_OFFSET]; /* Buffer for sending frames, etc */
char empty; /* Empty character */
unsigned char buf[BUF_SIZE + 3]; /* Output Buffer */
unsigned char buf[BUF_SIZE + BUF_SHIFT]; /* Output Buffer */
int lasttimeout;
struct timeval last;
short signal; /* Signal level (file side) */
short ssindex; /* Signal ssindex (file side) */
unsigned char zero_count; /* counter of consecutive zero samples */
unsigned char next_flag;
};
@@ -95,21 +98,48 @@ static short nbl2bit[16][4] = {
* Sets the index to the step size table for the next encode.
*/
static inline short
decode (unsigned char encoded, short *ssindex)
static inline void
decode (unsigned char encoded, short *ssindex, short *signal, unsigned char *rkey, unsigned char *next)
{
short diff, step;
step = stpsz[*ssindex];
diff = nbl2bit[encoded][0] * (step * nbl2bit[encoded][1] +
(step >> 1) * nbl2bit[encoded][2] +
(step >> 2) * nbl2bit[encoded][3] +
(step >> 3));
diff = step * nbl2bit[encoded][1] +
(step >> 1) * nbl2bit[encoded][2] +
(step >> 2) * nbl2bit[encoded][3] +
(step >> 3);
if (nbl2bit[encoded][2] && (step & 0x1))
diff++;
diff *= nbl2bit[encoded][0];
if ( *next & 0x1 )
*signal -= 8;
else if ( *next & 0x2 )
*signal += 8;
*signal += diff;
if (*signal > 2047)
*signal = 2047;
else if (*signal < -2047)
*signal = -2047;
*next = 0;
if( encoded & 0x7 )
*rkey = 0;
else if ( ++(*rkey) == 24 ) {
*rkey = 0;
if (*signal > 0)
*next = 0x1;
else if (*signal < 0)
*next = 0x2;
}
*ssindex = *ssindex + indsft[(encoded & 7)];
if (*ssindex < 0)
*ssindex = 0;
else if (*ssindex > 48)
*ssindex = 48;
return (diff);
}
/*
@@ -129,6 +159,7 @@ adpcm (short csig, short *ssindex, short *signal)
{
short diff, step;
unsigned char encoded;
unsigned char zero_count, next_flag;
step = stpsz[*ssindex];
/*
* Clip csig if too large or too small
@@ -160,7 +191,8 @@ adpcm (short csig, short *ssindex, short *signal)
if (diff >= step)
encoded |= 1;
*signal += decode (encoded, ssindex);
decode (encoded, ssindex, signal, &zero_count, &next_flag);
return (encoded);
}
@@ -233,13 +265,12 @@ static struct ast_frame *vox_read(struct ast_filestream *s, int *whennext)
int res;
int x;
/* Send a frame from the file to the appropriate channel */
s->fr.frametype = AST_FRAME_VOICE;
s->fr.subclass = AST_FORMAT_ADPCM;
s->fr.offset = AST_FRIENDLY_OFFSET;
s->fr.mallocd = 0;
s->fr.data = s->buf;
if ((res = read(s->fd, s->buf + 3, BUF_SIZE)) < 1) {
if ((res = read(s->fd, s->buf + BUF_SHIFT, BUF_SIZE)) < 1) {
if (res)
ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
return NULL;
@@ -248,13 +279,15 @@ static struct ast_frame *vox_read(struct ast_filestream *s, int *whennext)
s->buf[0] = s->ssindex & 0xff;
s->buf[1] = (s->signal >> 8) & 0xff;
s->buf[2] = s->signal & 0xff;
s->buf[3] = s->zero_count;
s->buf[4] = s->next_flag;
/* Do the decoder to be sure we get the right stuff in the signal and index fields. */
for (x=3;x<res+3;x++) {
s->signal += decode(s->buf[x] >> 4, &s->ssindex);
s->signal += decode(s->buf[x] & 0xf, &s->ssindex);
for (x=BUF_SHIFT;x<res+BUF_SHIFT;x++) {
decode (s->buf[x] >> 4, &s->ssindex, &s->signal, &s->zero_count, &s->next_flag);
decode (s->buf[x] & 0xf, &s->ssindex, &s->signal, &s->zero_count, &s->next_flag);
}
s->fr.samples = res * 2;
s->fr.datalen = res + 3;
s->fr.datalen = res + BUF_SHIFT;
*whennext = s->fr.samples;
return &s->fr;
}
@@ -270,11 +303,11 @@ static int vox_write(struct ast_filestream *fs, struct ast_frame *f)
ast_log(LOG_WARNING, "Asked to write non-ADPCM frame (%d)!\n", f->subclass);
return -1;
}
if (f->datalen < 3) {
ast_log(LOG_WARNING, "Invalid frame of data (< 3 bytes long) from %s\n", f->src);
if (f->datalen < BUF_SHIFT) {
ast_log(LOG_WARNING, "Invalid frame of data (< %d bytes long) from %s\n", BUF_SHIFT, f->src);
return -1;
}
if ((res = write(fs->fd, f->data + 3, f->datalen - 3)) != f->datalen - 3) {
if ((res = write(fs->fd, f->data + BUF_SHIFT, f->datalen - BUF_SHIFT)) != f->datalen - BUF_SHIFT) {
ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
return -1;
}