From edefa0cdd8d0a83aeb6b545b1914a7a2a0bcbd30 Mon Sep 17 00:00:00 2001
From: Timothy Pearson <tpearson@raptorengineering.com>
Date: Fri, 22 Nov 2019 10:08:11 -0600
Subject: Detect HR timestamp compatible version of ALSA before using HR
 timestamp functions

---
 configure              | 12 ++++++++++--
 libavdevice/alsa.c     |  4 ++++
 libavdevice/alsa_dec.c |  4 ++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 1de90e9..9273076 100755
--- a/configure
+++ b/configure
@@ -2186,6 +2186,7 @@ SYSTEM_FEATURES="
 SYSTEM_FUNCS="
     access
     aligned_malloc
+    alsa_hr_ts
     arc4random
     clock_gettime
     closesocket
@@ -6515,8 +6516,15 @@ else
 EOF
 fi
 
-enabled alsa && { check_pkg_config alsa alsa "alsa/asoundlib.h" snd_pcm_htimestamp ||
-                  check_lib alsa alsa/asoundlib.h snd_pcm_htimestamp -lasound; }
+if enabled alsa; then
+    check_pkg_config alsa alsa "alsa/asoundlib.h" snd_pcm_htimestamp ||
+    check_lib alsa alsa/asoundlib.h snd_pcm_htimestamp -lasound
+    if check_type "alsa/asoundlib.h alsa/pcm.h" snd_pcm_tstamp_type_t; then
+        enable alsa_hr_ts
+    else
+        warn "High resolution timestamps not supported by your ALSA version.  Streaming A/V sync may suffer!"
+    fi
+fi
 
 enabled libjack &&
     require_pkg_config libjack jack jack/jack.h jack_port_get_latency_range
diff --git a/libavdevice/alsa.c b/libavdevice/alsa.c
index 10ffe56..903ed94 100644
--- a/libavdevice/alsa.c
+++ b/libavdevice/alsa.c
@@ -272,6 +272,7 @@ av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
     }
 
     s->use_driver_timestamps = 0;
+#if HAVE_ALSA_HR_TS
     if (snd_pcm_hw_params_supports_audio_ts_type(hw_params, 0)) {
         av_log(ctx, AV_LOG_INFO, "capture device supports compat timestamps\n");
         s->use_driver_timestamps |= 1;
@@ -296,6 +297,7 @@ av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
         av_log(ctx, AV_LOG_INFO, "capture device supports link synchronized timestamps\n");
         s->use_driver_timestamps |= 32;
     }
+#endif
 
     res = snd_pcm_sw_params_malloc(&sw_params);
     if (res < 0) {
@@ -320,6 +322,7 @@ av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
         goto fail;
     }
 
+#if HAVE_ALSA_HR_TS
     res = snd_pcm_sw_params_set_tstamp_type(h, sw_params, SND_PCM_TSTAMP_TYPE_MONOTONIC_RAW);
     if (res < 0) {
         av_log(ctx, AV_LOG_ERROR, "cannot set timestamp mode (%s)\n",
@@ -327,6 +330,7 @@ av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
         snd_pcm_sw_params_free(sw_params);
         goto fail;
     }
+#endif
 
     res = snd_pcm_sw_params(h, sw_params);
     if (res < 0) {
diff --git a/libavdevice/alsa_dec.c b/libavdevice/alsa_dec.c
index 902fba3..0b3b7e4 100644
--- a/libavdevice/alsa_dec.c
+++ b/libavdevice/alsa_dec.c
@@ -104,7 +104,9 @@ static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
     int res;
     int64_t dts;
     snd_pcm_sframes_t delay = 0;
+#if HAVE_ALSA_HR_TS
     snd_pcm_audio_tstamp_config_t tstamp_config;
+#endif
 
     if (av_new_packet(pkt, s->period_size * s->frame_size) < 0) {
         return AVERROR(EIO);
@@ -127,6 +129,7 @@ static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
     }
 
     dts = 0;
+#if HAVE_ALSA_HR_TS
     if (s->use_driver_timestamps) {
         tstamp_config.type_requested = 1;
         tstamp_config.report_delay = 1;
@@ -142,6 +145,7 @@ static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
             delay = snd_pcm_status_get_delay(s->st);
         }
     }
+#endif
     if (dts == 0) {
         // Driver timestamps not supported
         // Fall back to system timestamps
-- 
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