diff --git a/README.codecnegotiation-branch b/README.codecnegotiation-branch
new file mode 100644
index 0000000..5e9146a
--- /dev/null
+++ b/README.codecnegotiation-branch
@@ -0,0 +1,66 @@
+Codec API changes branch
+========================
+
+Why do we need this?
+---------------------
+
+There are many problems with the existing codec negotiation implementation, many
+people wants to change it. But all has one unresolved problem -- all changes,
+related to codec negotiation, need to modify all channel modules and most
+applications.
+
+This problem exists, because there is no easy and consistend API, that can be
+used for some standard situations, and there are a lot of duplicated code.
+
+What is the main idea of this patches?
+---------------------------------------
+
+I think, that direct access to chan->(raw)(read|write|native)format can be only
+from special functions. Loadable modules don't need to has direct access to
+this variables, only through channel API.
+
+After incorporating this to trunk, we could easily incorporate all patches like
+4825 (codec negotiation rework).
+
+This patch DO NOT CHANGE any existing API's, only add some new functions, and
+convert most of code to using new API.
+
+Changes description
+-------------------
+
+Added functions (all this functions static inline):
+
+ - ast_channel_best_codec(chan) = ast_best_codec(chan->nativecodecs)
+   This need, because in future nativecodecs can be changed from int to struct
+   type;
+ - ast_get_read_format(chan) = chan->readformat
+ - ast_get_write_format(chan) = chan->writeformat
+ - ast_request_inherit -- wrapper around ast_request, that can:
+    - copy type from parent channel, if type not set;
+    - copy formats from parent channel;
+ - ast_channel_getformatname  = ast_getformatname(chan->nativeformats)
+ - ast_channel_format_reset =
+ 	ast_set_read_format(chan->readformat);
+	ast_set_write_format(chan->writeformat);
+
+Related changes:
+ - most places, where can be used new functions changed to use it
+
+Progress
+--------
+ - ast_chan_best_codec(chan)   -- all modules fixed
+ - ast_get_(read|write)_format -- ~80% modules fixed (may be fixed after commit
+   as junitor project)
+ - ast_request_inherit         -- all modules fixed (would be used for easily
+   integrate 4825 -- it contain many chunks with ast_request);
+
+Contacts
+--------
+
+If you have questions about this patches, or ideas for improvement, write me:
+Denis Smirnov <mithraen@freesource.info>
+
+Discussions are best done on the asterisk-dev mailing list.
+
+Bugs are reported to the bug tracker, issue #6725
+
diff --git a/apps/app_amd.c b/apps/app_amd.c
index e5dee1e..9739e61 100644
--- a/apps/app_amd.c
+++ b/apps/app_amd.c
@@ -129,7 +129,7 @@ static void isAnsweringMachine(struct ast_channel *chan, void *data)
 	);
 
 	if (option_verbose > 2)
-		ast_verbose(VERBOSE_PREFIX_3 "AMD: %s %s %s (Fmt: %d)\n", chan->name ,chan->cid.cid_ani, chan->cid.cid_rdnis, chan->readformat);
+		ast_verbose(VERBOSE_PREFIX_3 "AMD: %s %s %s (Fmt: %d)\n", chan->name ,chan->cid.cid_ani, chan->cid.cid_rdnis, ast_get_read_format(chan));
 
 	/* Lets parse the arguments. */
 	if (!ast_strlen_zero(parse)) {
@@ -162,7 +162,7 @@ static void isAnsweringMachine(struct ast_channel *chan, void *data)
 				minimumWordLength, betweenWordsSilence, maximumNumberOfWords, silenceThreshold );
 
 	/* Set read format to signed linear so we get signed linear frames in */
-	readFormat = chan->readformat;
+	readFormat = ast_get_read_format(chan);
 	if (ast_set_read_format(chan, AST_FORMAT_SLINEAR) < 0 ) {
 		ast_log(LOG_WARNING, "AMD: Channel [%s]. Unable to set to linear mode, giving up\n", chan->name );
 		pbx_builtin_setvar_helper(chan , "AMDSTATUS", "");
diff --git a/apps/app_chanisavail.c b/apps/app_chanisavail.c
index c6931d8..5c2c8d1 100644
--- a/apps/app_chanisavail.c
+++ b/apps/app_chanisavail.c
@@ -121,7 +121,7 @@ static int chanavail_exec(struct ast_channel *chan, void *data)
 				snprintf(trychan, sizeof(trychan), "%s/%s",cur,number);
 				status = inuse = ast_device_state(trychan);
 			}
-			if ((inuse <= 1) && (tempchan = ast_request(tech, chan->nativeformats, number, &status))) {
+			if ((inuse <= 1) && (tempchan = ast_request_inherit(chan, tech, number, &status))) {
 					pbx_builtin_setvar_helper(chan, "AVAILCHAN", tempchan->name);
 					/* Store the originally used channel too */
 					snprintf(tmp, sizeof(tmp), "%s/%s", tech, number);
diff --git a/apps/app_dial.c b/apps/app_dial.c
index 7f731bc..347a384 100644
--- a/apps/app_dial.c
+++ b/apps/app_dial.c
@@ -1288,7 +1288,7 @@ static int dial_exec_full(struct ast_channel *chan, void *data, struct ast_flags
 		}
 		ast_copy_string(numsubst, number, sizeof(numsubst));
 		/* Request the peer */
-		tc = ast_request(tech, chan->nativeformats, numsubst, &cause);
+		tc = ast_request_inherit(chan, tech, numsubst, &cause);
 		if (!tc) {
 			/* If we can't, just go on to the next call */
 			ast_log(LOG_WARNING, "Unable to create channel of type '%s' (cause %d - %s)\n",
@@ -1328,7 +1328,7 @@ static int dial_exec_full(struct ast_channel *chan, void *data, struct ast_flags
 						ast_verbose(VERBOSE_PREFIX_3 "Forwarding %s to '%s/%s' prevented.\n",
 							chan->name, tech, stuff);
 				} else {
-					tc = ast_request(tech, chan->nativeformats, stuff, &cause);
+					tc= ast_request_inherit(chan, tech, stuff, &cause);
 				}
 				if (!tc)
 					ast_log(LOG_NOTICE, "Unable to create local channel for call forward to '%s/%s' (cause = %d)\n", tech, stuff, cause);
diff --git a/apps/app_dictate.c b/apps/app_dictate.c
index 55d8ba9..03232ce 100644
--- a/apps/app_dictate.c
+++ b/apps/app_dictate.c
@@ -119,7 +119,7 @@ static int dictate_exec(struct ast_channel *chan, void *data)
 	if (args.argc > 1 && args.filename) {
 		filename = args.filename;
 	} 
-	oldr = chan->readformat;
+	oldr = ast_get_read_format(chan);
 	if ((res = ast_set_read_format(chan, AST_FORMAT_SLINEAR)) < 0) {
 		ast_log(LOG_WARNING, "Unable to set to linear mode.\n");
 		ast_module_user_remove(u);
diff --git a/apps/app_dumpchan.c b/apps/app_dumpchan.c
index ca7897e..7676d28 100644
--- a/apps/app_dumpchan.c
+++ b/apps/app_dumpchan.c
@@ -115,8 +115,8 @@ static int serialize_showchan(struct ast_channel *c, char *buf, size_t size)
 			 c->_state,
 			 c->rings,
 			 ast_getformatname_multiple(formatbuf, sizeof(formatbuf), c->nativeformats),
-			 ast_getformatname_multiple(formatbuf, sizeof(formatbuf), c->writeformat),
-			 ast_getformatname_multiple(formatbuf, sizeof(formatbuf), c->readformat),
+			 ast_getformatname_multiple(formatbuf, sizeof(formatbuf), ast_get_write_format(c)),
+			 ast_getformatname_multiple(formatbuf, sizeof(formatbuf), ast_get_read_format(c)),
 			 c->fds[0], c->fin & ~DEBUGCHAN_FLAG, (c->fin & DEBUGCHAN_FLAG) ? " (DEBUGGED)" : "",
 			 c->fout & ~DEBUGCHAN_FLAG, (c->fout & DEBUGCHAN_FLAG) ? " (DEBUGGED)" : "", (long)c->whentohangup,
 			 hour,
diff --git a/apps/app_echo.c b/apps/app_echo.c
index 4b2c940..bcd431e 100644
--- a/apps/app_echo.c
+++ b/apps/app_echo.c
@@ -54,14 +54,11 @@ static char *descrip =
 static int echo_exec(struct ast_channel *chan, void *data)
 {
 	int res = -1;
-	int format;
 	struct ast_module_user *u;
 
 	u = ast_module_user_add(chan);
-
-	format = ast_best_codec(chan->nativeformats);
-	ast_set_write_format(chan, format);
-	ast_set_read_format(chan, format);
+	
+	ast_set_best_format(chan);
 
 	while (ast_waitfor(chan, -1) > -1) {
 		struct ast_frame *f = ast_read(chan);
diff --git a/apps/app_festival.c b/apps/app_festival.c
index 1fa935e..1a4b179 100644
--- a/apps/app_festival.c
+++ b/apps/app_festival.c
@@ -191,7 +191,7 @@ static int send_waveform_to_channel(struct ast_channel *chan, char *waveform, in
 	ast_stopstream(chan);
 	ast_indicate(chan, -1);
 	
-	owriteformat = chan->writeformat;
+	owriteformat = ast_get_write_format(chan);
 	res = ast_set_write_format(chan, AST_FORMAT_SLINEAR);
 	if (res < 0) {
 		ast_log(LOG_WARNING, "Unable to set write format to signed linear\n");
diff --git a/apps/app_ices.c b/apps/app_ices.c
index 91725fd..b6b40fe 100644
--- a/apps/app_ices.c
+++ b/apps/app_ices.c
@@ -143,7 +143,7 @@ static int ices_exec(struct ast_channel *chan, void *data)
 		return -1;
 	}
 
-	oreadformat = chan->readformat;
+	oreadformat = ast_get_read_format(chan);
 	res = ast_set_read_format(chan, AST_FORMAT_SLINEAR);
 	if (res < 0) {
 		close(fds[0]);
diff --git a/apps/app_mp3.c b/apps/app_mp3.c
index e0df37d..1bd479b 100644
--- a/apps/app_mp3.c
+++ b/apps/app_mp3.c
@@ -154,7 +154,7 @@ static int mp3_exec(struct ast_channel *chan, void *data)
 	
 	ast_stopstream(chan);
 
-	owriteformat = chan->writeformat;
+	owriteformat = ast_get_write_format(chan);
 	res = ast_set_write_format(chan, AST_FORMAT_SLINEAR);
 	if (res < 0) {
 		ast_log(LOG_WARNING, "Unable to set write format to signed linear\n");
diff --git a/apps/app_nbscat.c b/apps/app_nbscat.c
index 1fb51e6..c6bfa66 100644
--- a/apps/app_nbscat.c
+++ b/apps/app_nbscat.c
@@ -139,7 +139,7 @@ static int NBScat_exec(struct ast_channel *chan, void *data)
 	
 	ast_stopstream(chan);
 
-	owriteformat = chan->writeformat;
+	owriteformat = ast_get_write_format(chan);
 	res = ast_set_write_format(chan, AST_FORMAT_SLINEAR);
 	if (res < 0) {
 		ast_log(LOG_WARNING, "Unable to set write format to signed linear\n");
diff --git a/apps/app_queue.c b/apps/app_queue.c
index 716141c..ab8bf5b 100644
--- a/apps/app_queue.c
+++ b/apps/app_queue.c
@@ -1652,7 +1652,7 @@ static int ring_entry(struct queue_ent *qe, struct callattempt *tmp, int *busies
 		location = "";
 
 	/* Request the peer */
-	tmp->chan = ast_request(tech, qe->chan->nativeformats, location, &status);
+	tmp->chan = ast_request_inherit(qe->chan, tech, location, &status);
 	if (!tmp->chan) {			/* If we can't, just go on to the next call */
 		if (qe->chan->cdr)
 			ast_cdr_busy(qe->chan->cdr);
@@ -1979,7 +1979,7 @@ static struct callattempt *wait_for_answer(struct queue_ent *qe, struct callatte
 					if (option_verbose > 2)
 						ast_verbose(VERBOSE_PREFIX_3 "Now forwarding %s to '%s/%s' (thanks to %s)\n", in->name, tech, stuff, o->chan->name);
 					/* Setup parameters */
-					o->chan = ast_request(tech, in->nativeformats, stuff, &status);
+					o->chan = ast_request_inherit(in, tech, stuff, &status);
 					if (status != o->oldstatus)
 						update_dial_status(qe->parent, o->member, status);						
 					if (!o->chan) {
diff --git a/apps/app_record.c b/apps/app_record.c
index e06d84a..b58b74e 100644
--- a/apps/app_record.c
+++ b/apps/app_record.c
@@ -247,7 +247,7 @@ static int record_exec(struct ast_channel *chan, void *data)
 	/* The end of beep code.  Now the recording starts */
 		
 	if (silence > 0) {
-		rfmt = chan->readformat;
+		rfmt = ast_get_read_format(chan);
 		res = ast_set_read_format(chan, AST_FORMAT_SLINEAR);
 		if (res < 0) {
 			ast_log(LOG_WARNING, "Unable to set to linear mode, giving up\n");
diff --git a/apps/app_talkdetect.c b/apps/app_talkdetect.c
index 7d9376a..78f0b88 100644
--- a/apps/app_talkdetect.c
+++ b/apps/app_talkdetect.c
@@ -111,7 +111,7 @@ static int background_detect_exec(struct ast_channel *chan, void *data)
 		res = ast_answer(chan);
 	}
 	if (!res) {
-		origrformat = chan->readformat;
+		origrformat = ast_get_read_format(chan);
 		if ((res = ast_set_read_format(chan, AST_FORMAT_SLINEAR))) 
 			ast_log(LOG_WARNING, "Unable to set read format to linear!\n");
 	}
diff --git a/apps/app_test.c b/apps/app_test.c
index 02c354f..fda5019 100644
--- a/apps/app_test.c
+++ b/apps/app_test.c
@@ -72,7 +72,7 @@ static int measurenoise(struct ast_channel *chan, int ms, char *who)
 	struct timeval start;
 	struct ast_frame *f;
 	int rformat;
-	rformat = chan->readformat;
+	rformat = ast_get_read_format(chan);
 	if (ast_set_read_format(chan, AST_FORMAT_SLINEAR)) {
 		ast_log(LOG_NOTICE, "Unable to set to linear mode!\n");
 		return -1;
diff --git a/apps/app_waitforsilence.c b/apps/app_waitforsilence.c
index 55fc714..2c7f271 100644
--- a/apps/app_waitforsilence.c
+++ b/apps/app_waitforsilence.c
@@ -84,7 +84,7 @@ static int do_waiting(struct ast_channel *chan, int silencereqd, time_t waitstar
 	struct ast_dsp *sildet;	 /* silence detector dsp */
  	time_t now;
 
-	rfmt = chan->readformat; /* Set to linear mode */
+	rfmt = ast_get_read_format(chan); /* Set to linear mode */
 	res = ast_set_read_format(chan, AST_FORMAT_SLINEAR);
 	if (res < 0) {
 		ast_log(LOG_WARNING, "Unable to set channel to linear mode, giving up\n");
diff --git a/channels/chan_agent.c b/channels/chan_agent.c
index c83df41..bddc84d 100644
--- a/channels/chan_agent.c
+++ b/channels/chan_agent.c
@@ -200,12 +200,11 @@ static AST_LIST_HEAD_STATIC(agents, agent_pvt);	/*!< Holds the list of agents (l
 			ast->nativeformats = p->chan->nativeformats; \
 			if (option_debug) \
 				ast_log(LOG_DEBUG, "Resetting read to %d and write to %d\n", ast->readformat, ast->writeformat);\
-			ast_set_read_format(ast, ast->readformat); \
-			ast_set_write_format(ast, ast->writeformat); \
+			ast_channel_formats_reset(ast); \
 		} \
-		if (p->chan->readformat != ast->rawreadformat)  \
+		if (ast_get_read_format(p->chan) != ast->rawreadformat)  \
 			ast_set_read_format(p->chan, ast->rawreadformat); \
-		if (p->chan->writeformat != ast->rawwriteformat) \
+		if (ast_get_write_format(p->chan) != ast->rawwriteformat) \
 			ast_set_write_format(p->chan, ast->rawwriteformat); \
 	} \
 } while(0)
@@ -666,22 +665,22 @@ static int agent_call(struct ast_channel *ast, char *dest, int timeout)
 			ast_log(LOG_DEBUG, "Waited for stream, result '%d'\n", res);
 	}
 	if (!res) {
-		res = ast_set_read_format(p->chan, ast_best_codec(p->chan->nativeformats));
+		res = ast_set_read_format(p->chan, ast_channel_best_codec(p->chan));
 		if (option_debug > 2)
 			ast_log(LOG_DEBUG, "Set read format, result '%d'\n", res);
 		if (res)
-			ast_log(LOG_WARNING, "Unable to set read format to %s\n", ast_getformatname(ast_best_codec(p->chan->nativeformats)));
+			ast_log(LOG_WARNING, "Unable to set read format to %s\n", ast_getformatname(ast_channel_best_codec(p->chan)));
 	} else {
 		/* Agent hung-up */
 		p->chan = NULL;
 	}
 
 	if (!res) {
-		res = ast_set_write_format(p->chan, ast_best_codec(p->chan->nativeformats));
+		res = ast_set_write_format(p->chan, ast_channel_best_codec(p->chan));
 		if (option_debug > 2)
 			ast_log(LOG_DEBUG, "Set write format, result '%d'\n", res);
 		if (res)
-			ast_log(LOG_WARNING, "Unable to set write format to %s\n", ast_getformatname(ast_best_codec(p->chan->nativeformats)));
+			ast_log(LOG_WARNING, "Unable to set write format to %s\n", ast_getformatname(ast_channel_best_codec(p->chan)));
 	}
 	if(!res) {
 		/* Call is immediately up, or might need ack */
@@ -1970,14 +1969,14 @@ static int __login_exec(struct ast_channel *chan, void *data, int callbackmode)
 					AST_LIST_LOCK(&agents);
 					ast_mutex_lock(&p->lock);
 					if (!res) {
-						res = ast_set_read_format(chan, ast_best_codec(chan->nativeformats));
+						res = ast_set_read_format(chan, ast_channel_best_codec(chan));
 						if (res)
-							ast_log(LOG_WARNING, "Unable to set read format to %d\n", ast_best_codec(chan->nativeformats));
+							ast_log(LOG_WARNING, "Unable to set read format to %d\n", ast_channel_best_codec(chan));
 					}
 					if (!res) {
-						res = ast_set_write_format(chan, ast_best_codec(chan->nativeformats));
+						res = ast_set_write_format(chan, ast_channel_best_codec(chan));
 						if (res)
-							ast_log(LOG_WARNING, "Unable to set write format to %d\n", ast_best_codec(chan->nativeformats));
+							ast_log(LOG_WARNING, "Unable to set write format to %d\n", ast_channel_best_codec(chan));
 					}
 					/* Check once more just in case */
 					if (p->chan)
@@ -2026,7 +2025,7 @@ static int __login_exec(struct ast_channel *chan, void *data, int callbackmode)
 						ast_queue_log("NONE", chan->uniqueid, agent, "AGENTLOGIN", "%s", chan->name);
 						if (option_verbose > 1)
 							ast_verbose(VERBOSE_PREFIX_2 "Agent '%s' logged in (format %s/%s)\n", p->agent,
-								    ast_getformatname(chan->readformat), ast_getformatname(chan->writeformat));
+								    ast_getformatname(ast_get_read_format(chan)), ast_getformatname(chan->writeformat));
 						/* Login this channel and wait for it to go away */
 						p->chan = chan;
 						if (p->ackcall > 1)
diff --git a/channels/chan_features.c b/channels/chan_features.c
index 3c1285c..e8c9be9 100644
--- a/channels/chan_features.c
+++ b/channels/chan_features.c
@@ -187,12 +187,9 @@ static void update_features(struct feature_pvt *p, int index)
 			p->subs[index].owner->timingfd = p->subchan->timingfd;
 			p->subs[index].owner->alertpipe[0] = p->subchan->alertpipe[0];
 			p->subs[index].owner->alertpipe[1] = p->subchan->alertpipe[1];
-			if (p->subs[index].owner->nativeformats != p->subchan->readformat) {
-				p->subs[index].owner->nativeformats = p->subchan->readformat;
-				if (p->subs[index].owner->readformat)
-					ast_set_read_format(p->subs[index].owner, p->subs[index].owner->readformat);
-				if (p->subs[index].owner->writeformat)
-					ast_set_write_format(p->subs[index].owner, p->subs[index].owner->writeformat);
+			if (p->subs[index].owner->nativeformats != ast_get_read_format(p->subchan)) {
+				p->subs[index].owner->nativeformats = ast_get_read_format(p->subchan);
+				ast_channel_formats_reset(p->subs[index].owner);
 			}
 		} else{
 			restore_channel(p, index);
@@ -481,11 +478,11 @@ static struct ast_channel *features_new(struct feature_pvt *p, int state, int in
 		return NULL;
 	}
 	tmp->tech = &features_tech;
-	tmp->writeformat = p->subchan->writeformat;
+	tmp->writeformat = ast_get_write_format(p->subchan);
 	tmp->rawwriteformat = p->subchan->rawwriteformat;
-	tmp->readformat = p->subchan->readformat;
+	tmp->readformat = ast_get_read_format(p->subchan);
 	tmp->rawreadformat = p->subchan->rawreadformat;
-	tmp->nativeformats = p->subchan->readformat;
+	tmp->nativeformats = ast_get_read_format(p->subchan);
 	tmp->tech_pvt = p;
 	p->subs[index].owner = tmp;
 	if (!p->owner)
diff --git a/channels/chan_h323.c b/channels/chan_h323.c
index 096e8dd..008864b 100644
--- a/channels/chan_h323.c
+++ b/channels/chan_h323.c
@@ -342,8 +342,7 @@ static void __oh323_update_info(struct ast_channel *c, struct oh323_pvt *pvt)
 		if (h323debug)
 			ast_log(LOG_DEBUG, "Preparing %s for new native format\n", c->name);
 		c->nativeformats = pvt->nativeformats;
-		ast_set_read_format(c, c->readformat);
-		ast_set_write_format(c, c->writeformat);
+		ast_channel_formats_reset(c);
 	}
 	if (pvt->needhangup) {
 		if (h323debug)
@@ -784,8 +783,7 @@ static struct ast_frame *oh323_rtp_read(struct oh323_pvt *pvt)
 					ast_log(LOG_DEBUG, "Oooh, format changed to %d\n", f->subclass);
 				pvt->owner->nativeformats = f->subclass;
 				pvt->nativeformats = f->subclass;
-				ast_set_read_format(pvt->owner, pvt->owner->readformat);
-				ast_set_write_format(pvt->owner, pvt->owner->writeformat);
+				ast_channel_formats_reset(pvt->owner);
 				ast_channel_unlock(pvt->owner);
 			}
 			/* Do in-band DTMF detection */
@@ -850,7 +848,7 @@ static int oh323_write(struct ast_channel *c, struct ast_frame *frame)
 	} else {
 		if (!(frame->subclass & c->nativeformats)) {
 			ast_log(LOG_WARNING, "Asked to transmit frame type %d, while native formats is %d (read/write = %d/%d)\n",
-				frame->subclass, c->nativeformats, c->readformat, c->writeformat);
+				frame->subclass, c->nativeformats, ast_get_read_format(c), ast_get_write_format(c));
 			return 0;
 		}
 	}
@@ -1031,7 +1029,7 @@ static struct ast_channel *__oh323_new(struct oh323_pvt *pvt, int state, const c
 			fmt = global_options.capability;
 		ch->nativeformats = ast_codec_choose(&pvt->options.prefs, fmt, 1)/* | (pvt->jointcapability & AST_FORMAT_VIDEO_MASK)*/;
 		pvt->nativeformats = ch->nativeformats;
-		fmt = ast_best_codec(ch->nativeformats);
+		fmt = ast_channel_best_codec(ch);
 		ch->writeformat = fmt;
 		ch->rawwriteformat = fmt;
 		ch->readformat = fmt;
diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index a1cba30..4ce727e 100644
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -6188,8 +6188,8 @@ static int iax_park(struct ast_channel *chan1, struct ast_channel *chan2)
 	chan2m = ast_channel_alloc(0, AST_STATE_DOWN, 0, 0, "IAXPeer/%s",chan2->name);
 	if (chan2m && chan1m) {
 		/* Make formats okay */
-		chan1m->readformat = chan1->readformat;
-		chan1m->writeformat = chan1->writeformat;
+		chan1m->readformat = ast_get_read_format(chan1);
+		chan1m->writeformat = ast_get_write_format(chan1);
 		ast_channel_masquerade(chan1m, chan1);
 		/* Setup the extensions and such */
 		ast_copy_string(chan1m->context, chan1->context, sizeof(chan1m->context));
@@ -6199,8 +6199,8 @@ static int iax_park(struct ast_channel *chan1, struct ast_channel *chan2)
 		/* We make a clone of the peer channel too, so we can play
 		   back the announcement */
 		/* Make formats okay */
-		chan2m->readformat = chan2->readformat;
-		chan2m->writeformat = chan2->writeformat;
+		chan2m->readformat = ast_get_read_format(chan2);
+		chan2m->writeformat = ast_get_write_format(chan2);
 		ast_channel_masquerade(chan2m, chan2);
 		/* Setup the extensions and such */
 		ast_copy_string(chan2m->context, chan2->context, sizeof(chan2m->context));
@@ -8100,8 +8100,7 @@ static struct ast_channel *iax2_request(const char *type, int format, void *data
 			}
 			c->nativeformats = native;
 		}
-		c->readformat = ast_best_codec(c->nativeformats);
-		c->writeformat = c->readformat;
+		c->writeformat = c->readformat = ast_channel_best_codec(c);
 	}
 
 	return c;
diff --git a/channels/chan_mgcp.c b/channels/chan_mgcp.c
index bdb7047..df791c0 100644
--- a/channels/chan_mgcp.c
+++ b/channels/chan_mgcp.c
@@ -1204,8 +1204,7 @@ static struct ast_frame *mgcp_rtp_read(struct mgcp_subchannel *sub)
 				if (option_debug)
 					ast_log(LOG_DEBUG, "Oooh, format changed to %d\n", f->subclass);
 				sub->owner->nativeformats = f->subclass;
-				ast_set_read_format(sub->owner, sub->owner->readformat);
-				ast_set_write_format(sub->owner, sub->owner->writeformat);
+				ast_channel_formats_reset(sub->owner);
 			}
 			/* Courtesy fearnor aka alex@pilosoft.com */
 			if ((sub->parent->dtmfmode & MGCP_DTMF_INBAND) && (sub->parent->dsp)) {
@@ -1244,7 +1243,7 @@ static int mgcp_write(struct ast_channel *ast, struct ast_frame *frame)
 	} else {
 		if (!(frame->subclass & ast->nativeformats)) {
 			ast_log(LOG_WARNING, "Asked to transmit frame type %d, while native formats is %d (read/write = %d/%d)\n",
-				frame->subclass, ast->nativeformats, ast->readformat, ast->writeformat);
+				frame->subclass, ast->nativeformats, ast_get_read_format(ast), ast_get_write_format(ast));
 			return -1;
 		}
 	}
@@ -1439,7 +1438,7 @@ static struct ast_channel *mgcp_new(struct mgcp_subchannel *sub, int state)
 		tmp->nativeformats = i->capability;
 		if (!tmp->nativeformats)
 			tmp->nativeformats = capability;
-		fmt = ast_best_codec(tmp->nativeformats);
+		fmt = ast_channel_best_codec(tmp);
 		ast_string_field_build(tmp, name, "MGCP/%s@%s-%d", i->name, i->parent->name, sub->id);
 		if (sub->rtp)
 			tmp->fds[0] = ast_rtp_fd(sub->rtp);
diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 2707f0c..f6e98e7 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -3879,7 +3879,7 @@ static struct ast_channel *sip_new(struct sip_pvt *i, int state, const char *tit
 	}
 
 	/* XXX Why are we choosing a codec from the native formats?? */
-	fmt = ast_best_codec(tmp->nativeformats);
+	fmt = ast_channel_best_codec(tmp);
 
 	/* If we have a prefcodec setting, we have an inbound channel that set a 
 	   preferred format for this call. Otherwise, we check the jointcapability
@@ -4150,8 +4150,7 @@ static struct ast_frame *sip_rtp_read(struct ast_channel *ast, struct sip_pvt *p
 				if (option_debug)
 					ast_log(LOG_DEBUG, "Oooh, format changed to %d\n", f->subclass);
 				p->owner->nativeformats = (p->owner->nativeformats & AST_FORMAT_VIDEO_MASK) | f->subclass;
-				ast_set_read_format(p->owner, p->owner->readformat);
-				ast_set_write_format(p->owner, p->owner->writeformat);
+				ast_channel_formats_reset(p->owner);
 			}
 			if ((ast_test_flag(&p->flags[0], SIP_DTMF) == SIP_DTMF_INBAND) && p->vad) {
 				f = ast_dsp_process(p->owner, p->vad, f);
@@ -5257,8 +5256,7 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req)
 				ast_getformatname_multiple(s2, BUFSIZ, p->owner->nativeformats));
 		}
 		p->owner->nativeformats = ast_codec_choose(&p->prefs, p->jointcapability, 1) | (p->capability & vpeercapability);
-		ast_set_read_format(p->owner, p->owner->readformat);
-		ast_set_write_format(p->owner, p->owner->writeformat);
+		ast_channel_formats_reset(p->owner);
 	}
 	
 	/* Turn on/off music on hold if we are holding/unholding */
@@ -12738,8 +12736,8 @@ static int sip_park(struct ast_channel *chan1, struct ast_channel *chan2, struct
 	}
 
 	/* Make formats okay */
-	transferee->readformat = chan1->readformat;
-	transferee->writeformat = chan1->writeformat;
+	transferee->readformat = ast_get_read_format(chan1);
+	transferee->writeformat = ast_get_write_format(chan1);
 
 	/* Prepare for taking over the channel */
 	ast_channel_masquerade(transferee, chan1);
@@ -12753,8 +12751,8 @@ static int sip_park(struct ast_channel *chan1, struct ast_channel *chan2, struct
 	   back the announcement */
 
 	/* Make formats okay */
-	transferer->readformat = chan2->readformat;
-	transferer->writeformat = chan2->writeformat;
+	transferer->readformat = ast_get_read_format(chan2);
+	transferer->writeformat = ast_get_write_format(chan2);
 
 	/* Prepare for taking over the channel */
 	ast_channel_masquerade(transferer, chan2);
diff --git a/channels/chan_skinny.c b/channels/chan_skinny.c
index 927172e..66c3693 100644
--- a/channels/chan_skinny.c
+++ b/channels/chan_skinny.c
@@ -2502,8 +2502,7 @@ static struct ast_frame *skinny_rtp_read(struct skinny_subchannel *sub)
 				if (option_debug)
 					ast_log(LOG_DEBUG, "Oooh, format changed to %d\n", f->subclass);
 				ast->nativeformats = f->subclass;
-				ast_set_read_format(ast, ast->readformat);
-				ast_set_write_format(ast, ast->writeformat);
+				ast_channel_formats_reset(sub->owner);
 			}
 		}
 	}
@@ -2534,7 +2533,7 @@ static int skinny_write(struct ast_channel *ast, struct ast_frame *frame)
 	} else {
 		if (!(frame->subclass & ast->nativeformats)) {
 			ast_log(LOG_WARNING, "Asked to transmit frame type %d, while native formats is %d (read/write = %d/%d)\n",
-				frame->subclass, ast->nativeformats, ast->readformat, ast->writeformat);
+				frame->subclass, ast->nativeformats, ast_get_read_format(ast), ast_get_write_format(ast));
 			return -1;
 		}
 	}
@@ -2732,8 +2731,13 @@ static struct ast_channel *skinny_new(struct skinny_line *l, int state)
 		tmp->tech_pvt = sub;
 		tmp->nativeformats = l->capability;
 		if (!tmp->nativeformats)
+<<<<<<< .merge_file_rO1Utp
 			tmp->nativeformats = default_capability;
 		fmt = ast_best_codec(tmp->nativeformats);
+=======
+			tmp->nativeformats = capability;
+		fmt = ast_channel_best_codec(tmp);
+>>>>>>> .merge_file_9lWybm
 		if (skinnydebug)
 			ast_verbose("skinny_new: tmp->nativeformats=%d fmt=%d\n", tmp->nativeformats, fmt);
 		if (sub->rtp) {
diff --git a/funcs/func_channel.c b/funcs/func_channel.c
index 77777a5..fe39893 100644
--- a/funcs/func_channel.c
+++ b/funcs/func_channel.c
@@ -73,9 +73,9 @@ static int func_channel_read(struct ast_channel *chan, const char *function,
 		/* ast_getformatname_multiple(buf, len, chan->nativeformats & AST_FORMAT_VIDEO_MASK); */
 		ast_copy_string(buf, ast_getformatname(chan->nativeformats & AST_FORMAT_VIDEO_MASK), len);
 	else if (!strcasecmp(data, "audioreadformat"))
-		ast_copy_string(buf, ast_getformatname(chan->readformat), len);
+		ast_copy_string(buf, ast_getformatname(ast_get_read_format(chan)), len);
 	else if (!strcasecmp(data, "audiowriteformat"))
-		ast_copy_string(buf, ast_getformatname(chan->writeformat), len);
+		ast_copy_string(buf, ast_getformatname(ast_get_write_format(chan)), len);
 	else if (!strcasecmp(data, "tonezone") && chan->zone)
 		locked_copy_string(chan, buf, chan->zone->country, len);
 	else if (!strcasecmp(data, "language"))
diff --git a/include/asterisk/channel.h b/include/asterisk/channel.h
index 0d07b5d..3c7da70 100644
--- a/include/asterisk/channel.h
+++ b/include/asterisk/channel.h
@@ -152,7 +152,7 @@ extern "C" {
 #include "asterisk/utils.h"
 #include "asterisk/linkedlists.h"
 #include "asterisk/stringfields.h"
-#include "asterisk/compiler.h"
+#include "asterisk/options.h"
 
 
 #define AST_MAX_FDS		8
@@ -674,6 +674,18 @@ void  ast_channel_free(struct ast_channel *);
  */
 struct ast_channel *ast_request(const char *type, int format, void *data, int *status);
 
+
+/*! \brief call ast_request with format/type of parent channel
+ */
+static inline struct ast_channel *ast_request_inherit(struct ast_channel *chan, const char *type, void *data, int *status)
+{
+    if( type == NULL ) {
+	return ast_request(chan->tech->type, chan->nativeformats, data, status);
+    } else {
+	return ast_request(type, chan->nativeformats, data, status);
+    }
+}
+
 /*!
  * \brief Request a channel of a given type, with data as optional information used 
  * by the low level module and attempt to place a call on it
@@ -894,6 +906,28 @@ int ast_prod(struct ast_channel *chan);
  */
 int ast_set_read_format(struct ast_channel *chan, int format);
 
+/*! \brief Gets read format from channel chan 
+ * \param chan channel to get info
+ * Get read format for channel
+ * Returns read format
+ */
+static inline int ast_get_read_format(struct ast_channel *chan)
+{
+    return chan->readformat;
+}
+
+/*! Gets write format from channel chan */
+/*! 
+ * \param chan channel to get info
+ * Get write format for channel
+ * Returns write format
+ */
+static inline int ast_get_write_format(struct ast_channel *chan)
+{
+    return chan->writeformat;
+}
+
+
 /*! \brief Sets write format on channel chan
  * Set write format for channel to whichever component of "format" is best. 
  * \param chan channel to change
@@ -1105,6 +1139,67 @@ int ast_channel_setoption(struct ast_channel *channel, int option, void *data, i
 /* Choose the best codec...  Uhhh...   Yah. */
 int ast_best_codec(int fmts);
 
+/*! 
+ * \brief Pick the best codec from channel nativeformats
+ * \param channel channel, from that nativeformats used
+ */
+static inline int ast_channel_best_codec(struct ast_channel *channel)
+{
+#ifndef BUG_4825 
+	return ast_best_codec(channel->nativeformats);
+#else	
+	return ast_best_codec(channel->nativeformats.audio_bits);
+#endif	
+}
+/*! \brief Get the names of a set of formats
+ * \param buf a buffer for the output string
+ * \param size size of buf (bytes)
+ * \param channel the channel
+ * Prints a list of readable codec names corresponding to "format".
+ * ex: for format=AST_FORMAT_GSM|AST_FORMAT_SPEEX|AST_FORMAT_ILBC it will return "0x602 (GSM|SPEEX|ILBC)"
+ * \return The return value is buf.
+ */
+inline static char * ast_channel_getformatname_multiple(char *buf, size_t size, struct ast_channel *chan)
+{
+	return ast_getformatname_multiple(buf, size, chan->nativeformats);
+}
+
+
+static inline char * ast_channel_getformatname(struct ast_channel *chan)
+{
+#ifndef BUG_4825 
+	return chan ? ast_getformatname(chan->nativeformats) : "undefined";
+#else	
+	return chan ? ast_getformatname(chan->nativeformats.audio_bits) : "undefined";
+#endif	
+}
+
+static inline void ast_channel_formats_reset(struct ast_channel *channel)
+{
+	int r, w;
+	r = ast_get_read_format(channel);
+	w = ast_get_write_format(channel);
+
+	if (option_debug)
+		ast_log(LOG_DEBUG, "Resetting read to %d and write to %d on channel %s\n", r, w, channel->name);
+
+	if (r)
+		ast_set_read_format(channel, r);
+
+	if (w)
+		ast_set_write_format(channel, w);
+}
+
+/*!
+ * \brief Set best format, identical to read/write
+ * \param channel channel, from that nativeformats used and formats set
+ */
+static inline void ast_set_best_format(struct ast_channel *channel)
+{
+    int format = ast_channel_best_codec(channel);
+    ast_set_read_format(channel, format);
+    ast_set_write_format(channel, format);
+}
 
 /*! Checks the value of an option */
 /*! 
@@ -1418,3 +1513,4 @@ void ast_channel_whisper_stop(struct ast_channel *chan);
 #endif
 
 #endif /* _ASTERISK_CHANNEL_H */
+
diff --git a/res/res_adsi.c b/res/res_adsi.c
index 62f8381..34ee4f3 100644
--- a/res/res_adsi.c
+++ b/res/res_adsi.c
@@ -377,8 +377,8 @@ int ast_adsi_transmit_message_full(struct ast_channel *chan, unsigned char *msg,
 	int writeformat, readformat;
 	int waitforswitch = 0;
 
-	writeformat = chan->writeformat;
-	readformat = chan->readformat;
+	writeformat = ast_get_write_format(chan);
+	readformat = ast_get_read_format(chan);
 
 	newdatamode = chan->adsicpe & ADSI_FLAG_DATAMODE;
 
diff --git a/res/res_agi.c b/res/res_agi.c
index 55f5c65..317738c 100644
--- a/res/res_agi.c
+++ b/res/res_agi.c
@@ -933,7 +933,7 @@ static int handle_recordfile(struct ast_channel *chan, AGI *agi, int argc, char
 	}
 
         if (silence > 0) {
-        	rfmt = chan->readformat;
+        	rfmt = ast_get_read_format(chan);
                 res = ast_set_read_format(chan, AST_FORMAT_SLINEAR);
                 if (res < 0) {
                 	ast_log(LOG_WARNING, "Unable to set to linear mode, giving up\n");
@@ -2077,7 +2077,7 @@ static int eagi_exec(struct ast_channel *chan, void *data)
 
 	if (chan->_softhangup)
 		ast_log(LOG_WARNING, "If you want to run AGI on hungup channels you should use DeadAGI!\n");
-	readformat = chan->readformat;
+	readformat = ast_get_read_format(chan);
 	if (ast_set_read_format(chan, AST_FORMAT_SLINEAR)) {
 		ast_log(LOG_WARNING, "Unable to set channel '%s' to linear mode\n", chan->name);
 		return -1;
diff --git a/res/res_features.c b/res/res_features.c
index 1aba2c1..0ffacf0 100644
--- a/res/res_features.c
+++ b/res/res_features.c
@@ -447,8 +447,8 @@ int ast_masq_park_call(struct ast_channel *rchan, struct ast_channel *peer, int
 	}
 
 	/* Make formats okay */
-	chan->readformat = rchan->readformat;
-	chan->writeformat = rchan->writeformat;
+	chan->readformat = ast_get_read_format(rchan);
+	chan->writeformat = ast_get_write_format(rchan);
 	ast_channel_masquerade(chan, rchan);
 
 	/* Setup the extensions and such */
@@ -784,7 +784,7 @@ static int builtin_atxfer(struct ast_channel *chan, struct ast_channel *peer, st
 
 	l = strlen(xferto);
 	snprintf(xferto + l, sizeof(xferto) - l, "@%s/n", transferer_real_context);	/* append context */
-	newchan = ast_feature_request_and_dial(transferer, "Local", ast_best_codec(transferer->nativeformats),
+	newchan = ast_feature_request_and_dial(transferer, "Local", ast_channel_best_codec(transferer),
 		xferto, atxfernoanswertimeout, &outstate, transferer->cid.cid_num, transferer->cid.cid_name);
 	ast_indicate(transferer, -1);
 	if (!newchan) {
@@ -831,8 +831,8 @@ static int builtin_atxfer(struct ast_channel *chan, struct ast_channel *peer, st
 		return -1;
 	}
 	/* Make formats okay */
-	xferchan->readformat = transferee->readformat;
-	xferchan->writeformat = transferee->writeformat;
+	xferchan->readformat = ast_get_read_format(transferee);
+	xferchan->writeformat = ast_get_write_format(transferee);
 	ast_channel_masquerade(xferchan, transferee);
 	ast_explicit_goto(xferchan, transferee->context, transferee->exten, transferee->priority);
 	xferchan->_state = AST_STATE_UP;
diff --git a/res/res_musiconhold.c b/res/res_musiconhold.c
index 96e24a4..bfe6790 100644
--- a/res/res_musiconhold.c
+++ b/res/res_musiconhold.c
@@ -313,7 +313,7 @@ static void *moh_files_alloc(struct ast_channel *chan, void *params)
 				state->pos = ast_random() % class->total_files;
 		}
 
-		state->origwfmt = chan->writeformat;
+		state->origwfmt = ast_get_write_format(chan);
 
 		if (option_verbose > 2)
 			ast_verbose(VERBOSE_PREFIX_3 "Started music on hold, class '%s', on %s\n", class->name, chan->name);
@@ -689,7 +689,7 @@ static void *moh_alloc(struct ast_channel *chan, void *params)
 	struct mohclass *class = params;
 
 	if ((res = mohalloc(class))) {
-		res->origwfmt = chan->writeformat;
+		res->origwfmt = ast_get_write_format(chan);
 		if (ast_set_write_format(chan, class->format)) {
 			ast_log(LOG_WARNING, "Unable to set channel '%s' to format '%s'\n", chan->name, ast_codec2str(class->format));
 			moh_release(NULL, res);