avdevice/dshow: query graph and sample time only once

No need to query twice, use value we've already unconditionally got.
Improve variable names

Signed-off-by: Diederick Niehorster <dcnieho@gmail.com>
Reviewed-by: Roger Pack <rogerdpack2@gmail.com>

libavdevice/dshow_pin.c

@@ -295,9 +295,10 @@ long ff_dshow_meminputpin_Receive(DShowMemInputPin *this, IMediaSample *sample)
     uint8_t *buf;
     int buf_size; /* todo should be a long? */
     int index;
-    int64_t curtime;
-    int64_t orig_curtime;
+    int64_t chosentime;
+    int64_t sampletime;
     int64_t graphtime;
+    int use_sample_time = 1;
     const char *devtypename = (devtype == VideoDevice) ? "video" : "audio";
     IReferenceClock *clock = pin->filter->clock;
     int64_t dummy;
@@ -313,24 +314,27 @@ long ff_dshow_meminputpin_Receive(DShowMemInputPin *this, IMediaSample *sample)
     s = priv_data;
     ctx = s->priv_data;
 
-    IMediaSample_GetTime(sample, &orig_curtime, &dummy);
-    orig_curtime += pin->filter->start_time;
+    IMediaSample_GetTime(sample, &sampletime, &dummy);
     IReferenceClock_GetTime(clock, &graphtime);
     if (devtype == VideoDevice && !ctx->use_video_device_timestamps) {
         /* PTS from video devices is unreliable. */
-        IReferenceClock_GetTime(clock, &curtime);
+        chosentime = graphtime;
+        use_sample_time = 0;
     } else {
-        IMediaSample_GetTime(sample, &curtime, &dummy);
-        if(curtime > 400000000000000000LL) {
+        if (sampletime > 400000000000000000LL) {
             /* initial frames sometimes start < 0 (shown as a very large number here,
-               like 437650244077016960 which FFmpeg doesn't like.
+               like 437650244077016960 which FFmpeg doesn't like).
                TODO figure out math. For now just drop them. */
             av_log(NULL, AV_LOG_DEBUG,
-                "dshow dropping initial (or ending) frame with odd PTS too high %"PRId64"\n", curtime);
+                "dshow dropping initial (or ending) frame with odd PTS too high %"PRId64"\n", sampletime);
             return S_OK;
         }
-        curtime += pin->filter->start_time;
+        chosentime = sampletime;
     }
+    // media sample time is relative to graph start time
+    sampletime += pin->filter->start_time;
+    if (use_sample_time)
+        chosentime += pin->filter->start_time;
 
     buf_size = IMediaSample_GetActualDataLength(sample);
     IMediaSample_GetPointer(sample, &buf);
@@ -338,8 +342,8 @@ long ff_dshow_meminputpin_Receive(DShowMemInputPin *this, IMediaSample *sample)
 
     av_log(NULL, AV_LOG_VERBOSE, "dshow passing through packet of type %s size %8d "
         "timestamp %"PRId64" orig timestamp %"PRId64" graph timestamp %"PRId64" diff %"PRId64" %s\n",
-        devtypename, buf_size, curtime, orig_curtime, graphtime, graphtime - orig_curtime, ctx->device_name[devtype]);
-    pin->filter->callback(priv_data, index, buf, buf_size, curtime, devtype);
+        devtypename, buf_size, chosentime, sampletime, graphtime, graphtime - sampletime, ctx->device_name[devtype]);
+    pin->filter->callback(priv_data, index, buf, buf_size, chosentime, devtype);
 
     return S_OK;
 }