Commit 6144b6bcb7 for asterisk.org
commit 6144b6bcb73d8651566973f3cf9e1b0bbba84403
Author: Mike Bradeen <mbradeen@sangoma.com>
Date: Wed Jun 10 11:00:17 2026 -0600
app_mixmonitor: Fix duplex recording for non 8K codecs
The native sampling of duplex recording is set to match the raw 8K
output format. If one or more of the streams being recorded is above
8K, the frame size coming into the mixmonitor is too large and needs
to be translated to 8K before being mixed into the stereo frame to
avoid garbled and mistimed audio
Fixes: #1779
diff --git a/apps/app_mixmonitor.c b/apps/app_mixmonitor.c
index 3ca978dfdd..ef2caaad68 100644
--- a/apps/app_mixmonitor.c
+++ b/apps/app_mixmonitor.c
@@ -60,6 +60,7 @@
#include "asterisk/mixmonitor.h"
#include "asterisk/format_cache.h"
#include "asterisk/beep.h"
+#include "asterisk/translate.h"
/*** DOCUMENTATION
<application name="MixMonitor" language="en_US">
@@ -667,6 +668,81 @@ static void clear_mixmonitor_recipient_list(struct mixmonitor *mixmonitor)
#define SAMPLES_PER_FRAME 160
+/* This will allocate and free the translator path as needed so it can be re-used on subsequent calls */
+static void fill_frame_buffer(struct ast_frame *source_frame,
+ struct ast_format *target_format,
+ struct ast_format **last_source_format,
+ struct ast_trans_pvt **translator_path,
+ short *dest_buf,
+ size_t dest_buf_size,
+ const char *direction)
+{
+ struct ast_frame *converted_frame = NULL;
+
+ if (!source_frame) {
+ memset(dest_buf, 0, dest_buf_size);
+ return;
+ }
+
+ /*
+ * We only need to worry about translating if the frame format does not match
+ * the expected format of the frame we are writing.
+ */
+ if (ast_format_cmp(target_format, source_frame->subclass.format) == AST_FORMAT_CMP_NOT_EQUAL) {
+ /*
+ * If the format changed from the last frame or if this is the first frame
+ * that does not match the native format, we need to set up a new
+ * translator path.
+ */
+ if (ast_format_cmp(*last_source_format, source_frame->subclass.format) == AST_FORMAT_CMP_NOT_EQUAL
+ || !*translator_path) {
+ ast_debug(3, "%s frame format changed from %s to %s, building translator path to %s\n",
+ direction,
+ *last_source_format ? ast_format_get_name(*last_source_format) : "none",
+ ast_format_get_name(source_frame->subclass.format),
+ ast_format_get_name(target_format));
+
+ if (*translator_path) {
+ ast_translator_free_path(*translator_path);
+ }
+
+ *translator_path = ast_translator_build_path(target_format, source_frame->subclass.format);
+ }
+
+ if (*translator_path) {
+ converted_frame = ast_translate(*translator_path, source_frame, 0);
+ }
+
+ /*
+ * If creating the translated frame or translator path failed, write silence for this frame. We will
+ * try rebuilding the translator path later if it is still needed.
+ */
+ if (converted_frame) {
+ memcpy(dest_buf, converted_frame->data.ptr, dest_buf_size);
+ ast_frame_free(converted_frame, 1);
+ } else {
+ memset(dest_buf, 0, dest_buf_size);
+ }
+ } else {
+ memcpy(dest_buf, source_frame->data.ptr, dest_buf_size);
+
+ /*
+ * If we are doing native frame copying, we can free the translator path if
+ * it exists. We will create a new one later if needed.
+ */
+ if (*translator_path) {
+ ast_translator_free_path(*translator_path);
+ *translator_path = NULL;
+ ast_debug(3, "%s frame format changed from %s to %s, translator path no longer needed\n",
+ direction,
+ *last_source_format ? ast_format_get_name(*last_source_format) : "none",
+ ast_format_get_name(source_frame->subclass.format));
+ }
+ }
+
+ *last_source_format = source_frame->subclass.format;
+}
+
static void mixmonitor_free(struct mixmonitor *mixmonitor)
{
if (mixmonitor) {
@@ -783,6 +859,11 @@ static void *mixmonitor_thread(void *obj)
struct ast_filestream **fs_read = NULL;
struct ast_filestream **fs_write = NULL;
+ struct ast_format *last_format_read = NULL;
+ struct ast_format *last_format_write = NULL;
+ struct ast_trans_pvt *trans_pvt_read = NULL;
+ struct ast_trans_pvt *trans_pvt_write = NULL;
+
unsigned int oflags;
int errflag = 0;
struct ast_format *format_slin;
@@ -875,6 +956,11 @@ static void *mixmonitor_thread(void *obj)
if (ast_test_flag(mixmonitor, MUXFLAG_INTERLEAVED)) {
/* The 'D' option is set, so mix the frame as an interleaved dual channel frame */
int i;
+ /*
+ * We are fed by a call to ast_audiohook_read_frame_all specifying format_slin. However
+ * we may get frames back in a different format. Either way, we we will translate them
+ * to the format with the correct frame size before writing into these buffers.
+ */
short read_buf[SAMPLES_PER_FRAME];
short write_buf[SAMPLES_PER_FRAME];
short stereo_buf[SAMPLES_PER_FRAME * 2];
@@ -889,17 +975,16 @@ static void *mixmonitor_thread(void *obj)
fr = NULL;
}
- if (fr_read) {
- memcpy(read_buf, fr_read->data.ptr, sizeof(read_buf));
- } else {
- memset(read_buf, 0, sizeof(read_buf));
- }
+ /*
+ * Depending on the input codec's rate (which may change during the call) we may get frames in
+ * a slin format that does not match the native format_slin of the mixmonitor. In that case
+ * we need to translate.
+ */
+ fill_frame_buffer(fr_read, format_slin, &last_format_read, &trans_pvt_read,
+ read_buf, sizeof(read_buf), "Read");
- if (fr_write) {
- memcpy(write_buf, fr_write->data.ptr, sizeof(write_buf));
- } else {
- memset(write_buf, 0, sizeof(write_buf));
- }
+ fill_frame_buffer(fr_write, format_slin, &last_format_write, &trans_pvt_write,
+ write_buf, sizeof(write_buf), "Write");
for (i = 0; i < SAMPLES_PER_FRAME; i++) {
stereo_buf[i * 2] = read_buf[i];
@@ -907,7 +992,7 @@ static void *mixmonitor_thread(void *obj)
}
stereo_frame.data.ptr = stereo_buf;
- stereo_frame.subclass.format = ast_format_cache_get_slin_by_rate(SAMPLES_PER_FRAME);
+ stereo_frame.subclass.format = format_slin;
fr = ast_frdup(&stereo_frame);
}
@@ -959,6 +1044,16 @@ frame_cleanup:
}
ast_mutex_unlock(&mixmonitor->mixmonitor_ds->lock);
+ /* Free the translate paths */
+ if (trans_pvt_read) {
+ ast_translator_free_path(trans_pvt_read);
+ trans_pvt_read = NULL;
+ }
+ if (trans_pvt_write) {
+ ast_translator_free_path(trans_pvt_write);
+ trans_pvt_write = NULL;
+ }
+
/* kill the audiohook */
destroy_monitor_audiohook(mixmonitor);
diff --git a/include/asterisk/audiohook.h b/include/asterisk/audiohook.h
index b2e831dd87..7d0cce123a 100644
--- a/include/asterisk/audiohook.h
+++ b/include/asterisk/audiohook.h
@@ -176,6 +176,9 @@ struct ast_frame *ast_audiohook_read_frame(struct ast_audiohook *audiohook, size
* \param write_frame if available, we'll copy the write buffer to this.
* \return frame on success
* \retval NULL on failure
+ * \note The read_frame and write_frame may be in a different format from what was specified in format depending on the sample rate
+ * of the hooked channel's codec - ie; if we are requesting slin, but are hooked on channel using a 16K codec like g722, the
+ * read and write frames will be slin16.
*/
struct ast_frame *ast_audiohook_read_frame_all(struct ast_audiohook *audiohook, size_t samples, struct ast_format *format, struct ast_frame **read_frame, struct ast_frame **write_frame);