[asterisk-commits] trunk r19673 - /trunk/formats/format_wav_gsm.c
asterisk-commits at lists.digium.com
asterisk-commits at lists.digium.com
Wed Apr 12 18:29:55 MST 2006
Author: tilghman
Date: Wed Apr 12 20:29:54 2006
New Revision: 19673
URL: http://svn.digium.com/view/asterisk?rev=19673&view=rev
Log:
Document the MSGSM format, and fix the uncalculated number of samples
Modified:
trunk/formats/format_wav_gsm.c
Modified: trunk/formats/format_wav_gsm.c
URL: http://svn.digium.com/view/asterisk/trunk/formats/format_wav_gsm.c?rev=19673&r1=19672&r2=19673&view=diff
==============================================================================
--- trunk/formats/format_wav_gsm.c (original)
+++ trunk/formats/format_wav_gsm.c Wed Apr 12 20:29:54 2006
@@ -56,7 +56,7 @@
#define GSM_FRAME_SIZE 33
#define MSGSM_FRAME_SIZE 65
-#define MSGSM_DATA_OFS 60 /* offset of data bytes */
+#define MSGSM_DATA_OFFSET 60 /* offset of data bytes */
#define GSM_SAMPLES 160 /* samples in a GSM block */
#define MSGSM_SAMPLES (2*GSM_SAMPLES) /* samples in an MSGSM block */
@@ -219,15 +219,16 @@
static int update_header(FILE *f)
{
off_t cur,end,bytes;
- int datalen,filelen;
-
+ int datalen, filelen, samples;
+
cur = ftello(f);
fseek(f, 0, SEEK_END);
end = ftello(f);
/* in a gsm WAV, data starts 60 bytes in */
- bytes = end - MSGSM_DATA_OFS;
+ bytes = end - MSGSM_DATA_OFFSET;
+ samples = bytes / GSM_FRAME_SIZE * MSGSM_SAMPLES;
datalen = htoll((bytes + 1) & ~0x1);
- filelen = htoll(52 + ((bytes + 1) & ~0x1));
+ filelen = htoll(MSGSM_DATA_OFFSET - 8 + ((bytes + 1) & ~0x1));
if (cur < 0) {
ast_log(LOG_WARNING, "Unable to find our position\n");
return -1;
@@ -237,7 +238,15 @@
return -1;
}
if (fwrite(&filelen, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to set write file size\n");
+ ast_log(LOG_WARNING, "Unable to write file size\n");
+ return -1;
+ }
+ if (fseek(f, 48, SEEK_SET)) {
+ ast_log(LOG_WARNING, "Unable to set our position\n");
+ return -1;
+ }
+ if (fwrite(&samples, 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write samples\n");
return -1;
}
if (fseek(f, 56, SEEK_SET)) {
@@ -245,7 +254,7 @@
return -1;
}
if (fwrite(&datalen, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to set write datalen\n");
+ ast_log(LOG_WARNING, "Unable to write datalen\n");
return -1;
}
if (fseeko(f, cur, SEEK_SET)) {
@@ -257,78 +266,111 @@
static int write_header(FILE *f)
{
- unsigned int hz=htoll(DEFAULT_SAMPLE_RATE); /* XXX the following are relate to DEFAULT_SAMPLE_RATE ? */
- unsigned int bhz = htoll(1625);
- unsigned int hs = htoll(20);
+ /* Samples per second (always 8000 for this format). */
+ unsigned int sample_rate = htoll(8000);
+ /* Bytes per second (always 1625 for this format). */
+ unsigned int byte_sample_rate = htoll(1625);
+ /* This is the size of the "fmt " subchunk */
+ unsigned int fmtsize = htoll(20);
+ /* WAV #49 */
unsigned short fmt = htols(49);
+ /* Mono = 1 channel */
unsigned short chans = htols(1);
- unsigned int fhs = htoll(4);
- unsigned int x_1 = htoll(65);
- unsigned short x_2 = htols(2);
- unsigned short x_3 = htols(320);
- unsigned int y_1 = htoll(20160);
+ /* Each block of data is exactly 65 bytes in size. */
+ unsigned short block_align = htols(MSGSM_FRAME_SIZE);
+ /* Not actually 2, but rounded up to the nearest bit */
+ unsigned short bits_per_sample = htols(2);
+ /* Needed for compressed formats */
+ unsigned short extra_format = htols(MSGSM_SAMPLES);
+ /* This is the size of the "fact" subchunk */
+ unsigned int factsize = htoll(4);
+ /* Number of samples in the data chunk */
+ unsigned int num_samples = htoll(0);
+ /* Number of bytes in the data chunk */
unsigned int size = htoll(0);
/* Write a GSM header, ignoring sizes which will be filled in later */
+
+ /* 0: Chunk ID */
if (fwrite("RIFF", 1, 4, f) != 4) {
ast_log(LOG_WARNING, "Unable to write header\n");
return -1;
}
+ /* 4: Chunk Size */
if (fwrite(&size, 1, 4, f) != 4) {
ast_log(LOG_WARNING, "Unable to write header\n");
return -1;
}
- if (fwrite("WAVEfmt ", 1, 8, f) != 8) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
- if (fwrite(&hs, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
+ /* 8: Chunk Format */
+ if (fwrite("WAVE", 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 12: Subchunk 1: ID */
+ if (fwrite("fmt ", 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 16: Subchunk 1: Size (minus 8) */
+ if (fwrite(&fmtsize, 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 20: Subchunk 1: Audio format (49) */
if (fwrite(&fmt, 1, 2, f) != 2) {
ast_log(LOG_WARNING, "Unable to write header\n");
return -1;
}
+ /* 22: Subchunk 1: Number of channels */
if (fwrite(&chans, 1, 2, f) != 2) {
ast_log(LOG_WARNING, "Unable to write header\n");
return -1;
}
- if (fwrite(&hz, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
- if (fwrite(&bhz, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
- if (fwrite(&x_1, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
- if (fwrite(&x_2, 1, 2, f) != 2) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
- if (fwrite(&x_3, 1, 2, f) != 2) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
+ /* 24: Subchunk 1: Sample rate */
+ if (fwrite(&sample_rate, 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 28: Subchunk 1: Byte rate */
+ if (fwrite(&byte_sample_rate, 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 32: Subchunk 1: Block align */
+ if (fwrite(&block_align, 1, 2, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 36: Subchunk 1: Bits per sample */
+ if (fwrite(&bits_per_sample, 1, 2, f) != 2) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 38: Subchunk 1: Extra format bytes */
+ if (fwrite(&extra_format, 1, 2, f) != 2) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 40: Subchunk 2: ID */
if (fwrite("fact", 1, 4, f) != 4) {
ast_log(LOG_WARNING, "Unable to write header\n");
return -1;
}
- if (fwrite(&fhs, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
- if (fwrite(&y_1, 1, 4, f) != 4) {
- ast_log(LOG_WARNING, "Unable to write header\n");
- return -1;
- }
+ /* 44: Subchunk 2: Size (minus 8) */
+ if (fwrite(&factsize, 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 48: Subchunk 2: Number of samples */
+ if (fwrite(&num_samples, 1, 4, f) != 4) {
+ ast_log(LOG_WARNING, "Unable to write header\n");
+ return -1;
+ }
+ /* 52: Subchunk 3: ID */
if (fwrite("data", 1, 4, f) != 4) {
ast_log(LOG_WARNING, "Unable to write header\n");
return -1;
}
+ /* 56: Subchunk 3: Size */
if (fwrite(&size, 1, 4, f) != 4) {
ast_log(LOG_WARNING, "Unable to write header\n");
return -1;
@@ -454,7 +496,7 @@
off_t offset=0, distance, max;
struct wavg_desc *s = (struct wavg_desc *)fs->private;
- off_t min = MSGSM_DATA_OFS;
+ off_t min = MSGSM_DATA_OFFSET;
off_t cur = ftello(fs->f);
fseek(fs->f, 0, SEEK_END);
max = ftello(fs->f); /* XXX ideally, should round correctly */
@@ -496,8 +538,7 @@
offset = ftello(fs->f);
/* since this will most likely be used later in play or record, lets stick
* to that level of resolution, just even frames boundaries */
- /* XXX why 52 ? */
- return (offset - 52)/MSGSM_FRAME_SIZE*MSGSM_SAMPLES;
+ return (offset - MSGSM_DATA_OFFSET)/MSGSM_FRAME_SIZE*MSGSM_SAMPLES;
}
static struct ast_format_lock me = { .usecnt = -1 };
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