translate: Enables native Packet-Loss Concealment (PLC) for supporting codecs.
authorJaco Kroon <jaco@uls.co.za>
Mon, 2 May 2016 10:57:03 +0000 (12:57 +0200)
committerAlexander Traud <pabstraud@compuserve.com>
Sun, 5 Jun 2016 10:02:52 +0000 (12:02 +0200)
ASTERISK-25629 #close

Change-Id: Ibfcf0670e094e9718d82fd9920f1fb2dae122006

main/translate.c

index 8d37e37..b7443b8 100644 (file)
@@ -358,6 +358,7 @@ static struct ast_trans_pvt *newpvt(struct ast_translator *t, struct ast_format
        pvt->f.offset = AST_FRIENDLY_OFFSET;
        pvt->f.src = pvt->t->name;
        pvt->f.data.ptr = pvt->outbuf.c;
+       pvt->f.seqno = 0x10000;
 
        /*
         * If the translator has not provided a format
@@ -524,13 +525,46 @@ struct ast_trans_pvt *ast_translator_build_path(struct ast_format *dst, struct a
 /*! \brief do the actual translation */
 struct ast_frame *ast_translate(struct ast_trans_pvt *path, struct ast_frame *f, int consume)
 {
-       struct ast_trans_pvt *p = path;
-       struct ast_frame *out;
+       const unsigned int rtp_seqno_max_value = 0xffff;
+       struct ast_frame *out_last, *out = NULL;
+       struct ast_trans_pvt *step;
        struct timeval delivery;
        int has_timing_info;
        long ts;
        long len;
-       int seqno;
+       int seqno, frames_missing;
+
+       /* Determine the amount of lost packets for PLC */
+       /* But not at start with first frame = path->f.seqno is still 0x10000 */
+       /* But not when there is no sequence number = frame created internally */
+       if ((path->f.seqno <= rtp_seqno_max_value) && (path->f.seqno != f->seqno)) {
+               if (f->seqno < path->f.seqno) { /* seqno overrun situation */
+                       frames_missing = rtp_seqno_max_value + f->seqno - path->f.seqno - 1;
+               } else {
+                       frames_missing = f->seqno - path->f.seqno - 1;
+               }
+               /* Out-of-order packet - more precise: late packet */
+               if ((rtp_seqno_max_value + 1) / 2 < frames_missing) {
+                       if (consume) {
+                               ast_frfree(f);
+                       }
+                       /*
+                        * Do not pass late packets to any transcoding module, because that
+                        * confuses the state of any library (packets inter-depend). With
+                        * the next packet, this one is going to be treated as lost packet.
+                        */
+                       return NULL;
+               }
+
+               if (frames_missing > 96) {
+                       struct ast_str *str = ast_str_alloca(256);
+
+                       /* not DEBUG but NOTICE because of WARNING in main/cannel.c:__ast_queue_frame */
+                       ast_log(LOG_NOTICE, "%d lost frame(s) %d/%d %s\n", frames_missing, f->seqno, path->f.seqno, ast_translate_path_to_str(path, &str));
+               }
+       } else {
+               frames_missing = 0;
+       }
 
        has_timing_info = ast_test_flag(f, AST_FRFLAG_HAS_TIMING_INFO);
        ts = f->ts;
@@ -560,18 +594,93 @@ struct ast_frame *ast_translate(struct ast_trans_pvt *path, struct ast_frame *f,
                         f->samples, ast_format_get_sample_rate(f->subclass.format)));
        }
        delivery = f->delivery;
-       for (out = f; out && p ; p = p->next) {
-               struct ast_frame *current = out;
-
-               do {
-                       framein(p, current);
-                       current = AST_LIST_NEXT(current, frame_list);
-               } while (current);
-               if (out != f) {
-                       ast_frfree(out);
+
+       for (out_last = NULL; frames_missing + 1; frames_missing--) {
+               struct ast_frame *frame_to_translate, *inner_head;
+               struct ast_frame missed = {
+                       .frametype = AST_FRAME_VOICE,
+                       .subclass.format = f->subclass.format,
+                       .datalen = 0,
+                       /* In RTP, the amount of samples might change anytime  */
+                       /* If that happened while frames got lost, what to do? */
+                       .samples = f->samples, /* FIXME */
+                       .src = __FUNCTION__,
+                       .data.uint32 = 0,
+                       .delivery.tv_sec = 0,
+                       .delivery.tv_usec = 0,
+                       .flags = 0,
+                       /* RTP sequence number is between 0x0001 and 0xffff */
+                       .seqno = (rtp_seqno_max_value + 1 + f->seqno - frames_missing) & rtp_seqno_max_value,
+               };
+
+               if (frames_missing) {
+                       frame_to_translate = &missed;
+               } else {
+                       frame_to_translate = f;
+               }
+
+               /* The translation path from one format to another might contain several steps */
+               /* out* collects the result for missed frame(s) and input frame(s) */
+               /* out is the result of the conversion of all frames, translated into the destination format */
+               /* out_last is the last frame in that list, to add frames faster */
+               for (step = path, inner_head = frame_to_translate; inner_head && step; step = step->next) {
+                       struct ast_frame *current, *inner_last, *inner_prev = frame_to_translate;
+
+                       /* inner* collects the result of each conversion step, the input for the next step */
+                       /* inner_head is a list of frames created by each conversion step */
+                       /* inner_last is the last frame in that list, to add frames faster */
+                       for (inner_last = NULL, current = inner_head; current; current = AST_LIST_NEXT(current, frame_list)) {
+                               struct ast_frame *tmp;
+
+                               framein(step, current);
+                               tmp = step->t->frameout(step);
+
+                               if (!tmp) {
+                                       continue;
+                               } else if (inner_last) {
+                                       struct ast_frame *t;
+
+                                       /* Determine the last frame of the list before appending to it */
+                                       while ((t = AST_LIST_NEXT(inner_last, frame_list))) {
+                                               inner_last = t;
+                                       }
+                                       AST_LIST_NEXT(inner_last, frame_list) = tmp;
+                               } else {
+                                       inner_prev = inner_head;
+                                       inner_head = tmp;
+                                       inner_last = tmp;
+                               }
+                       }
+
+                       /* The current step did not create any frames = no frames for the next step */
+                       /* The steps are not lost because framein buffered those for the next input frame */
+                       if (!inner_last) {
+                               inner_prev = inner_head;
+                               inner_head = NULL;
+                       }
+                       if (inner_prev != frame_to_translate) {
+                               ast_frfree(inner_prev); /* Frees just the intermediate lists */
+                       }
+               }
+
+               /* This frame created no frames after translation = continue with next frame */
+               /* The frame is not lost because framein buffered it to be combined with the next frame */
+               if (!inner_head) {
+                       continue;
+               } else if (out_last) {
+                       struct ast_frame *t;
+
+                       /* Determine the last frame of the list before appending to it */
+                       while ((t = AST_LIST_NEXT(out_last, frame_list))) {
+                               out_last = t;
+                       }
+                       AST_LIST_NEXT(out_last, frame_list) = inner_head;
+               } else {
+                       out = inner_head;
+                       out_last = inner_head;
                }
-               out = p->t->frameout(p);
        }
+
        if (out) {
                /* we have a frame, play with times */
                if (!ast_tvzero(delivery)) {