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avfvideosrc: improve timestamping and latency reporting

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Use AVF provided timings to timestamp output buffers. Use the running time at
the time the first buffer is produced to base timestamps on. Report 1-frame
latency based on the negotiated framerate instead of hardcoding 4ms latency.
This commit is contained in:
Alessandro Decina 2014-12-17 12:20:54 +11:00
parent 96ea75d75a
commit 0156725480
1 changed files with 36 additions and 24 deletions
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60
sys/applemedia/avfvideosrc.m
View file

@ -87,8 +87,10 @@ G_DEFINE_TYPE (GstAVFVideoSrc, gst_avf_video_src, GST_TYPE_PUSH_SRC);
GstCaps *caps;
GstVideoFormat format;
gint width, height;
GstClockTime duration;
GstClockTime latency;
guint64 offset;
GstClockTime startAVFTimestamp;
GstClockTime startTimestamp;
GstClockTime lastSampling;
guint count;
@ -129,7 +131,7 @@ G_DEFINE_TYPE (GstAVFVideoSrc, gst_avf_video_src, GST_TYPE_PUSH_SRC);
- (BOOL)query:(GstQuery *)query;
- (GstStateChangeReturn)changeState:(GstStateChange)transition;
- (GstFlowReturn)create:(GstBuffer **)buf;
- (void)timestampBuffer:(GstBuffer *)buf;
- (void)timestampBuffer:(GstBuffer *)buf sampleBuffer:(CMSampleBufferRef)sampleBuffer;
- (void)updateStatistics;
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
@ -571,6 +573,7 @@ didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
width = info.width;
height = info.height;
format = info.finfo->format;
latency = gst_util_uint64_scale (GST_SECOND, info.fps_d, info.fps_n);
dispatch_sync (mainQueue, ^{
int newformat;
@ -655,8 +658,10 @@ didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
bufQueue = [[NSMutableArray alloc] initWithCapacity:BUFFER_QUEUE_SIZE];
stopRequest = NO;
duration = gst_util_uint64_scale (GST_SECOND, DEVICE_FPS_D, DEVICE_FPS_N);
offset = 0;
latency = GST_CLOCK_TIME_NONE;
startAVFTimestamp = GST_CLOCK_TIME_NONE;
startTimestamp = GST_CLOCK_TIME_NONE;
lastSampling = GST_CLOCK_TIME_NONE;
count = 0;
@ -686,7 +691,7 @@ didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
if (device != nil) {
GstClockTime min_latency, max_latency;
min_latency = max_latency = duration; /* for now */
min_latency = max_latency = latency;
result = YES;
GST_DEBUG_OBJECT (element, "reporting latency of min %" GST_TIME_FORMAT
@ -807,7 +812,7 @@ didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
*buf = gst_core_media_buffer_new (sbuf, useVideoMeta);
CFRelease (sbuf);
[self timestampBuffer:*buf];
[self timestampBuffer:*buf sampleBuffer:sbuf];
if (doStats)
[self updateStatistics];
@ -816,29 +821,36 @@ didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
}
- (void)timestampBuffer:(GstBuffer *)buf
sampleBuffer:(CMSampleBufferRef)sbuf
{
GstClock *clock;
GstClockTime timestamp;
CMSampleTimingInfo time_info;
GstClockTime timestamp, duration;
CMItemCount num_timings;
GST_OBJECT_LOCK (element);
clock = GST_ELEMENT_CLOCK (element);
if (clock != NULL) {
gst_object_ref (clock);
timestamp = element->base_time;
} else {
timestamp = GST_CLOCK_TIME_NONE;
}
GST_OBJECT_UNLOCK (element);
timestamp = GST_CLOCK_TIME_NONE;
duration = GST_CLOCK_TIME_NONE;
if (CMSampleBufferGetOutputSampleTimingInfoArray(sbuf, 1, &time_info, &num_timings) == noErr) {
timestamp = gst_util_uint64_scale (GST_SECOND,
time_info.presentationTimeStamp.value, time_info.presentationTimeStamp.timescale);
duration = gst_util_uint64_scale (GST_SECOND,
time_info.duration.value, time_info.duration.timescale);
if (clock != NULL) {
timestamp = gst_clock_get_time (clock) - timestamp;
if (timestamp > duration)
timestamp -= duration;
else
timestamp = 0;
if (offset == 0) {
GstClock *clock;
gst_object_unref (clock);
clock = NULL;
GST_OBJECT_LOCK (element);
clock = GST_ELEMENT_CLOCK (element);
if (clock != NULL) {
startTimestamp = gst_clock_get_time (clock) - element->base_time;
}
GST_OBJECT_UNLOCK (element);
startAVFTimestamp = timestamp;
}
if (GST_CLOCK_TIME_IS_VALID (startAVFTimestamp) &&
GST_CLOCK_TIME_IS_VALID (startTimestamp))
timestamp = startTimestamp + (timestamp - startAVFTimestamp);
}
GST_BUFFER_OFFSET (buf) = offset++;