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Update support for SILK format.

Browse Source 
This commit adds scaffolding in order to support the SILK audio format
on calls. Roughly, this is what is added:

* Cached silk formats. One for each possible sample rate.
* ast_codec structures for each possible sample rate.
* RTP payload mappings for "SILK".

In addition, this change overhauls the res_format_attr_silk file in the
following ways:

* The "samplerate" attribute is scrapped. That's native to the format.
* There are far more checks to ensure that attributes have been
  allocated before attempting to reference them.
* We do not SDP fmtp lines for attributes set to 0.

These changes make way to be able to install a codec_silk module and
have it actually work. It also should allow for passthrough silk calls
in Asterisk.

Change-Id: Ieeb39c95a9fecc9246bcfd3c45a6c9b51c59380e
changes/36/3136/4
Mark Michelson 10 years ago
parent 43a78100c0
commit 28501051b4
5 changed files with 134 additions and 31 deletions
Show Stats Download Patch File Download Diff File

8
include/asterisk/format_cache.h
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@ -223,6 +223,14 @@ extern struct ast_format *ast_format_t140_red;
*/
extern struct ast_format *ast_format_none;
/*!
* \brief Built-in SILK format.
*/
extern struct ast_format *ast_format_silk8;
extern struct ast_format *ast_format_silk12;
extern struct ast_format *ast_format_silk16;
extern struct ast_format *ast_format_silk24;
/*!
* \brief Initialize format cache support within the core.
*

63
main/codec_builtin.c
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@ -772,6 +772,65 @@ static struct ast_codec t140 = {
.type = AST_MEDIA_TYPE_TEXT,
};
static int silk_samples(struct ast_frame *frame)
{
/* XXX This is likely not at all what's intended from this callback. However,
* since SILK is variable bit rate, I have no idea how to take a frame of data
* and determine the number of samples present. Instead, we base this on the
* sample rate of the codec and the expected number of samples to receive in 20ms.
* In testing, this has worked just fine.
*/
return ast_format_get_sample_rate(frame->subclass.format) / 50;
}
static struct ast_codec silk8 = {
.name = "silk",
.description = "SILK Codec (8 KHz)",
.type = AST_MEDIA_TYPE_AUDIO,
.sample_rate = 8000,
.minimum_ms = 20,
.maximum_ms = 100,
.default_ms = 20,
.minimum_bytes = 160,
.samples_count = silk_samples
};
static struct ast_codec silk12 = {
.name = "silk",
.description = "SILK Codec (12 KHz)",
.type = AST_MEDIA_TYPE_AUDIO,
.sample_rate = 12000,
.minimum_ms = 20,
.maximum_ms = 100,
.default_ms = 20,
.minimum_bytes = 240,
.samples_count = silk_samples
};
static struct ast_codec silk16 = {
.name = "silk",
.description = "SILK Codec (16 KHz)",
.type = AST_MEDIA_TYPE_AUDIO,
.sample_rate = 16000,
.minimum_ms = 20,
.maximum_ms = 100,
.default_ms = 20,
.minimum_bytes = 320,
.samples_count = silk_samples
};
static struct ast_codec silk24 = {
.name = "silk",
.description = "SILK Codec (24 KHz)",
.type = AST_MEDIA_TYPE_AUDIO,
.sample_rate = 24000,
.minimum_ms = 20,
.maximum_ms = 100,
.default_ms = 20,
.minimum_bytes = 480,
.samples_count = silk_samples
};
#define CODEC_REGISTER_AND_CACHE(codec) \
({ \
int __res_ ## __LINE__ = 0; \
@ -843,6 +902,10 @@ int ast_codec_builtin_init(void)
res |= CODEC_REGISTER_AND_CACHE(t140red);
res |= CODEC_REGISTER_AND_CACHE(t140);
res |= CODEC_REGISTER_AND_CACHE(none);
res |= CODEC_REGISTER_AND_CACHE_NAMED("silk8", silk8);
res |= CODEC_REGISTER_AND_CACHE_NAMED("silk12", silk12);
res |= CODEC_REGISTER_AND_CACHE_NAMED("silk16", silk16);
res |= CODEC_REGISTER_AND_CACHE_NAMED("silk24", silk24);
return res;
}

20
main/format_cache.c
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@ -232,6 +232,14 @@ struct ast_format *ast_format_t140_red;
*/
struct ast_format *ast_format_none;
/*!
* \brief Built-in "silk" format
*/
struct ast_format *ast_format_silk8;
struct ast_format *ast_format_silk12;
struct ast_format *ast_format_silk16;
struct ast_format *ast_format_silk24;
/*! \brief Number of buckets to use for the media format cache (should be prime for performance reasons) */
#define CACHE_BUCKETS 53
@ -331,6 +339,10 @@ static void format_cache_shutdown(void)
ao2_replace(ast_format_t140_red, NULL);
ao2_replace(ast_format_t140, NULL);
ao2_replace(ast_format_none, NULL);
ao2_replace(ast_format_silk8, NULL);
ao2_replace(ast_format_silk12, NULL);
ao2_replace(ast_format_silk16, NULL);
ao2_replace(ast_format_silk24, NULL);
}
int ast_format_cache_init(void)
@ -426,6 +438,14 @@ static void set_cached_format(const char *name, struct ast_format *format)
ao2_replace(ast_format_t140, format);
} else if (!strcmp(name, "none")) {
ao2_replace(ast_format_none, format);
} else if (!strcmp(name, "silk8")) {
ao2_replace(ast_format_silk8, format);
} else if (!strcmp(name, "silk12")) {
ao2_replace(ast_format_silk12, format);
} else if (!strcmp(name, "silk16")) {
ao2_replace(ast_format_silk16, format);
} else if (!strcmp(name, "silk24")) {
ao2_replace(ast_format_silk24, format);
}
}

10
main/rtp_engine.c
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@ -2198,6 +2198,11 @@ int ast_rtp_engine_init(void)
/* Opus and VP8 */
set_next_mime_type(ast_format_opus, 0, "audio", "opus", 48000);
set_next_mime_type(ast_format_vp8, 0, "video", "VP8", 90000);
/* DA SILK */
set_next_mime_type(ast_format_silk8, 0, "audio", "silk", 8000);
set_next_mime_type(ast_format_silk12, 0, "audio", "silk", 12000);
set_next_mime_type(ast_format_silk16, 0, "audio", "silk", 16000);
set_next_mime_type(ast_format_silk24, 0, "audio", "silk", 24000);
/* Define the static rtp payload mappings */
add_static_payload(0, ast_format_ulaw, 0);
@ -2243,6 +2248,11 @@ int ast_rtp_engine_init(void)
add_static_payload(100, ast_format_vp8, 0);
add_static_payload(107, ast_format_opus, 0);
add_static_payload(108, ast_format_silk8, 0);
add_static_payload(109, ast_format_silk12, 0);
add_static_payload(113, ast_format_silk16, 0);
add_static_payload(114, ast_format_silk24, 0);
return 0;
}

64
res/res_format_attr_silk.c
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@ -40,7 +40,6 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
* \note The only attribute that affects compatibility here is the sample rate.
*/
struct silk_attr {
unsigned int samplerate;
unsigned int maxbitrate;
unsigned int dtx;
unsigned int fec;
@ -54,10 +53,15 @@ static void silk_destroy(struct ast_format *format)
ast_free(attr);
}
static void attr_init(struct silk_attr *attr)
{
memset(attr, 0, sizeof(*attr));
}
static int silk_clone(const struct ast_format *src, struct ast_format *dst)
{
struct silk_attr *original = ast_format_get_attribute_data(src);
struct silk_attr *attr = ast_calloc(1, sizeof(*attr));
struct silk_attr *attr = ast_malloc(sizeof(*attr));
if (!attr) {
return -1;
@ -65,6 +69,8 @@ static int silk_clone(const struct ast_format *src, struct ast_format *dst)
if (original) {
*attr = *original;
} else {
attr_init(attr);
}
ast_format_set_attribute_data(dst, attr);
@ -109,17 +115,17 @@ static void silk_generate_sdp_fmtp(const struct ast_format *format, unsigned int
ast_str_append(str, 0, "a=fmtp:%u maxaveragebitrate=%u\r\n", payload, attr->maxbitrate);
}
ast_str_append(str, 0, "a=fmtp:%u usedtx=%u\r\n", payload, attr->dtx);
ast_str_append(str, 0, "a=fmtp:%u useinbandfec=%u\r\n", payload, attr->fec);
if (attr->dtx) {
ast_str_append(str, 0, "a=fmtp:%u usedtx=%u\r\n", payload, attr->dtx);
}
if (attr->fec) {
ast_str_append(str, 0, "a=fmtp:%u useinbandfec=%u\r\n", payload, attr->fec);
}
}
static enum ast_format_cmp_res silk_cmp(const struct ast_format *format1, const struct ast_format *format2)
{
struct silk_attr *attr1 = ast_format_get_attribute_data(format1);
struct silk_attr *attr2 = ast_format_get_attribute_data(format2);
if (((!attr1 || !attr1->samplerate) && (!attr2 || !attr2->samplerate)) ||
(attr1->samplerate == attr2->samplerate)) {
if (ast_format_get_sample_rate(format1) == ast_format_get_sample_rate(format2)) {
return AST_FORMAT_CMP_EQUAL;
}
@ -130,13 +136,10 @@ static struct ast_format *silk_getjoint(const struct ast_format *format1, const
{
struct silk_attr *attr1 = ast_format_get_attribute_data(format1);
struct silk_attr *attr2 = ast_format_get_attribute_data(format2);
unsigned int samplerate;
struct ast_format *jointformat;
struct silk_attr *attr_res;
samplerate = attr1->samplerate & attr2->samplerate;
/* sample rate is the only attribute that has any bearing on if joint capabilities exist or not */
if (samplerate) {
if (ast_format_get_sample_rate(format1) != ast_format_get_sample_rate(format2)) {
return NULL;
}
@ -145,22 +148,25 @@ static struct ast_format *silk_getjoint(const struct ast_format *format1, const
return NULL;
}
attr_res = ast_format_get_attribute_data(jointformat);
attr_res->samplerate = samplerate;
/* Take the lowest max bitrate */
attr_res->maxbitrate = MIN(attr1->maxbitrate, attr2->maxbitrate);
if (!attr1 || !attr2) {
attr_init(attr_res);
} else {
/* Take the lowest max bitrate */
attr_res->maxbitrate = MIN(attr1->maxbitrate, attr2->maxbitrate);
/* Only do dtx if both sides want it. DTX is a trade off between
* computational complexity and bandwidth. */
attr_res->dtx = attr1->dtx && attr2->dtx ? 1 : 0;
/* Only do dtx if both sides want it. DTX is a trade off between
* computational complexity and bandwidth. */
attr_res->dtx = attr1->dtx && attr2->dtx ? 1 : 0;
/* Only do FEC if both sides want it. If a peer specifically requests not
* to receive with FEC, it may be a waste of bandwidth. */
attr_res->fec = attr1->fec && attr2->fec ? 1 : 0;
/* Only do FEC if both sides want it. If a peer specifically requests not
* to receive with FEC, it may be a waste of bandwidth. */
attr_res->fec = attr1->fec && attr2->fec ? 1 : 0;
/* Use the maximum packetloss percentage between the two attributes. This affects how
* much redundancy is used in the FEC. */
attr_res->packetloss_percentage = MAX(attr1->packetloss_percentage, attr2->packetloss_percentage);
/* Use the maximum packetloss percentage between the two attributes. This affects how
* much redundancy is used in the FEC. */
attr_res->packetloss_percentage = MAX(attr1->packetloss_percentage, attr2->packetloss_percentage);
}
return jointformat;
}
@ -183,9 +189,7 @@ static struct ast_format *silk_set(const struct ast_format *format, const char *
}
attr = ast_format_get_attribute_data(cloned);
if (!strcasecmp(name, "sample_rate")) {
attr->samplerate = val;
} else if (!strcasecmp(name, "max_bitrate")) {
if (!strcasecmp(name, "max_bitrate")) {
attr->maxbitrate = val;
} else if (!strcasecmp(name, "dtx")) {
attr->dtx = val;
@ -205,9 +209,7 @@ static const void *silk_get(const struct ast_format *format, const char *name)
struct silk_attr *attr = ast_format_get_attribute_data(format);
unsigned int *val;
if (!strcasecmp(name, "sample_rate")) {
val = &attr->samplerate;
} else if (!strcasecmp(name, "max_bitrate")) {
if (!strcasecmp(name, "max_bitrate")) {
val = &attr->maxbitrate;
} else if (!strcasecmp(name, "dtx")) {
val = &attr->dtx;

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