chan_pjsip: fix switching sending codec when asymmetric_rtp_codec=no

The sending codec is switched to the receiving codec and then
is switched back to the best native codec on EVERY receiving RTP packets.
This is because after call of ast_channel_set_rawwriteformat there is call
of ast_set_write_format which calls set_format which sets rawwriteformat
to the best native format.

This patch adds a new function ast_set_write_format_path which set
specific write path on channel and uses this function to switch
the sending codec.

ASTERISK-26603 #close

Change-Id: I5b7d098f8b254ce8f45546e6c36e5d324737f71d

1 files changed, 36 insertions, 0 deletions

diff --git a/main/channel.c b/main/channel.c
index 278104cc9..357eb31ad 100644
--- a/main/channel.c
+++ b/main/channel.c
@@ -5447,6 +5447,42 @@ int ast_set_read_format_path(struct ast_channel *chan, struct ast_format *raw_fo
 	return 0;
 }
 
+int ast_set_write_format_path(struct ast_channel *chan, struct ast_format *core_format, struct ast_format *raw_format)
+{
+	struct ast_trans_pvt *trans_old;
+	struct ast_trans_pvt *trans_new;
+
+	if (ast_format_cmp(ast_channel_rawwriteformat(chan), raw_format) == AST_FORMAT_CMP_EQUAL
+		&& ast_format_cmp(ast_channel_writeformat(chan), core_format) == AST_FORMAT_CMP_EQUAL) {
+		/* Nothing to setup */
+		return 0;
+	}
+
+	ast_debug(1, "Channel %s setting write format path: %s -> %s\n",
+		ast_channel_name(chan),
+		ast_format_get_name(core_format),
+		ast_format_get_name(raw_format));
+
+	/* Setup new translation path. */
+	if (ast_format_cmp(raw_format, core_format) != AST_FORMAT_CMP_EQUAL) {
+		trans_new = ast_translator_build_path(raw_format, core_format);
+		if (!trans_new) {
+			return -1;
+		}
+	} else {
+		/* No translation needed. */
+		trans_new = NULL;
+	}
+	trans_old = ast_channel_writetrans(chan);
+	if (trans_old) {
+		ast_translator_free_path(trans_old);
+	}
+	ast_channel_writetrans_set(chan, trans_new);
+	ast_channel_set_rawwriteformat(chan, raw_format);
+	ast_channel_set_writeformat(chan, core_format);
+	return 0;
+}
+
 struct set_format_access {
 	const char *direction;
 	struct ast_trans_pvt *(*get_trans)(const struct ast_channel *chan);