From 22c5d46c65b2b94bf25f977f1e0319cfe0462ad0 Mon Sep 17 00:00:00 2001
From: Isaac Connor <isaac@zoneminder.com>
Date: Sun, 12 May 2019 12:14:03 -0400
Subject: [PATCH] rescale audio packet duration and pts before feeding to codec
 after resample

---
 src/zm_videostore.cpp | 41 +++++++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/src/zm_videostore.cpp b/src/zm_videostore.cpp
index 978dfd328..2130db03b 100644
--- a/src/zm_videostore.cpp
+++ b/src/zm_videostore.cpp
@@ -1011,7 +1011,6 @@ int VideoStore::writeAudioFramePacket(AVPacket *ipkt) {
     }
     zm_dump_frame(out_frame, "Out frame after resample");
 
-    out_frame->pts = in_frame->pts;
     // out_frame pts is in the input pkt pts... needs to be adjusted before sending to the encoder
     if ( out_frame->pts != AV_NOPTS_VALUE ) {
       if ( !audio_first_pts ) {
@@ -1065,6 +1064,8 @@ int VideoStore::writeAudioFramePacket(AVPacket *ipkt) {
       return 0;
     }
   #endif
+#if 0
+    // These should be set by encoder. They may not directly relate to ipkt due to buffering in codec.
     opkt.duration = av_rescale_q(opkt.duration, 
           audio_in_stream->time_base,
           audio_out_stream->time_base);
@@ -1074,6 +1075,7 @@ int VideoStore::writeAudioFramePacket(AVPacket *ipkt) {
     opkt.dts = av_rescale_q(opkt.dts, 
           audio_in_stream->time_base,
           audio_out_stream->time_base);
+#endif
     dumpPacket(audio_out_stream, &opkt, "raw opkt");
 
   } else {
@@ -1179,16 +1181,32 @@ int VideoStore::resample_audio() {
   Debug(2, "Converting %d to %d samples using swresample",
       in_frame->nb_samples, out_frame->nb_samples);
   ret = swr_convert_frame(resample_ctx, out_frame, in_frame);
-  zm_dump_frame(out_frame, "Out frame after convert");
-
-  // resampling doesn't change the duration, or set it.
-  out_frame->pkt_duration = in_frame->pkt_duration;
-
   if ( ret < 0 ) {
     Error("Could not resample frame (error '%s')",
         av_make_error_string(ret).c_str());
     return 0;
   }
+  zm_dump_frame(out_frame, "Out frame after convert");
+
+
+#if 0
+  // out_frame pts is in the input pkt pts... needs to be adjusted before sending to the encoder
+  if ( out_frame->pts != AV_NOPTS_VALUE ) {
+    if ( !audio_first_pts ) {
+      audio_first_pts = out_frame->pts;
+      Debug(1, "No audio_first_pts setting to %" PRId64, audio_first_pts);
+      out_frame->pts = 0;
+    } else {
+      out_frame->pts = out_frame->pts - audio_first_pts;
+    }
+    //
+  } else {
+    // sending AV_NOPTS_VALUE doesn't really work but we seem to get it in ffmpeg 2.8
+    out_frame->pts = audio_next_pts;
+  }
+  audio_next_pts = out_frame->pts + out_frame->nb_samples;
+#endif
+
   if ((ret = av_audio_fifo_realloc(fifo, av_audio_fifo_size(fifo) + out_frame->nb_samples)) < 0) {
     Error("Could not reallocate FIFO");
     return 0;
@@ -1214,6 +1232,17 @@ int VideoStore::resample_audio() {
     return 0;
   }
   out_frame->nb_samples = frame_size;
+  // resampling changes the duration because the timebase is 1/samples
+  if ( in_frame->pts != AV_NOPTS_VALUE ) {
+    out_frame->pkt_duration = av_rescale_q(
+        in_frame->pkt_duration,
+        audio_in_stream->time_base,
+        audio_out_stream->time_base);
+    out_frame->pts = av_rescale_q(
+        in_frame->pts,
+        audio_in_stream->time_base,
+        audio_out_stream->time_base);
+  }
 #else
 #if defined(HAVE_LIBAVRESAMPLE)
   ret = avresample_convert(resample_ctx, NULL, 0, 0, in_frame->data,