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h264parse: compute timestamp

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Lin YANG 2009-08-17 18:03:00 +08:00 committed by Sebastian Dröge
parent 9c08ece157
commit d520e426b0
1 changed files with 125 additions and 5 deletions
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130
gst/h264parse/gsth264parse.c
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@ -1001,22 +1001,20 @@ gst_h264_parse_chain_forward (GstH264Parse * h264parse, gboolean discont,
{
GstFlowReturn res = GST_FLOW_OK;
const guint8 *data;
GstClockTime timestamp;
if (discont) {
gst_adapter_clear (h264parse->adapter);
h264parse->discont = TRUE;
}
timestamp = GST_BUFFER_TIMESTAMP (buffer);
gst_adapter_push (h264parse->adapter, buffer);
while (res == GST_FLOW_OK) {
gint i;
gint next_nalu_pos = -1;
gint avail;
gboolean delta_unit = TRUE;
gboolean delta_unit = FALSE;
gboolean got_frame = FALSE;
avail = gst_adapter_available (h264parse->adapter);
if (avail < h264parse->nal_length_size + 1)
@ -1146,8 +1144,131 @@ gst_h264_parse_chain_forward (GstH264Parse * h264parse, gboolean discont,
/* we have a packet */
if (next_nalu_pos > 0) {
GstBuffer *outbuf;
GstClockTime outbuf_dts = GST_CLOCK_TIME_NONE;
outbuf = gst_adapter_take_buffer (h264parse->adapter, next_nalu_pos);
outbuf_dts = gst_adapter_prev_timestamp (h264parse->adapter, NULL); /* Better value for the second parameter? */
/* Ignore upstream dts that stalls or goes backward. Upstream elements
* like filesrc would keep on writing timestamp=0. XXX: is this correct?
* TODO: better way to detect whether upstream timstamps are useful */
if (h264parse->last_outbuf_dts != GST_CLOCK_TIME_NONE
&& outbuf_dts != GST_CLOCK_TIME_NONE
&& outbuf_dts <= h264parse->last_outbuf_dts)
outbuf_dts = GST_CLOCK_TIME_NONE;
if (got_frame || delta_unit) {
GstH264Sps *sps = h264parse->sps;
gint duration = 1;
if (!sps) {
GST_DEBUG_OBJECT (h264parse, "referred SPS invalid");
goto TIMESTAMP_FINISH;
} else if (!sps->timing_info_present_flag) {
GST_DEBUG_OBJECT (h264parse,
"unable to compute timestamp: timing info not present");
goto TIMESTAMP_FINISH;
} else if (sps->time_scale == 0) {
GST_DEBUG_OBJECT (h264parse,
"unable to compute timestamp: time_scale = 0 "
"(this is forbidden in spec; bitstream probably contains error)");
goto TIMESTAMP_FINISH;
}
if (sps->pic_struct_present_flag
&& h264parse->sei_pic_struct != (guint8) - 1) {
/* Note that when h264parse->sei_pic_struct == -1 (unspecified), there
* are ways to infer its value. This is related to computing the
* TopFieldOrderCnt and BottomFieldOrderCnt, which looks
* complicated and thus not implemented for the time being. Yet
* the value we have here is correct for many applications
*/
switch (h264parse->sei_pic_struct) {
case SEI_PIC_STRUCT_TOP_FIELD:
case SEI_PIC_STRUCT_BOTTOM_FIELD:
duration = 1;
break;
case SEI_PIC_STRUCT_FRAME:
case SEI_PIC_STRUCT_TOP_BOTTOM:
case SEI_PIC_STRUCT_BOTTOM_TOP:
duration = 2;
break;
case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
duration = 3;
break;
case SEI_PIC_STRUCT_FRAME_DOUBLING:
duration = 4;
break;
case SEI_PIC_STRUCT_FRAME_TRIPLING:
duration = 6;
break;
default:
GST_DEBUG_OBJECT (h264parse,
"h264parse->sei_pic_struct of unknown value %d. Not parsed",
h264parse->sei_pic_struct);
}
} else {
duration = h264parse->field_pic_flag ? 1 : 2;
}
/*
* h264parse.264 C.1.2 Timing of coded picture removal (equivalent to DTS):
* Tr,n(0) = initial_cpb_removal_delay[ SchedSelIdx ] / 90000
* Tr,n(n) = Tr,n(nb) + Tc * cpb_removal_delay(n)
* where
* Tc = num_units_in_tick / time_scale
*/
if (h264parse->ts_trn_nb != GST_CLOCK_TIME_NONE) {
/* buffering period is present */
if (outbuf_dts != GST_CLOCK_TIME_NONE) {
/* If upstream timestamp is valid, we respect it and adjust current
* reference point */
h264parse->ts_trn_nb = outbuf_dts -
(GstClockTime) gst_util_uint64_scale_int
(h264parse->sei_cpb_removal_delay * GST_SECOND,
sps->num_units_in_tick, sps->time_scale);
} else {
/* If no upstream timestamp is given, we write in new timestamp */
h264parse->dts = h264parse->ts_trn_nb +
(GstClockTime) gst_util_uint64_scale_int
(h264parse->sei_cpb_removal_delay * GST_SECOND,
sps->num_units_in_tick, sps->time_scale);
}
} else {
/* naive method: no removal delay specified, use best guess (add prev
* frame duration) */
if (outbuf_dts != GST_CLOCK_TIME_NONE)
h264parse->dts = outbuf_dts;
else if (h264parse->dts != GST_CLOCK_TIME_NONE)
h264parse->dts +=
(GstClockTime) gst_util_uint64_scale_int (h264parse->
cur_duration * GST_SECOND, sps->num_units_in_tick,
sps->time_scale);
else
h264parse->dts = 0; /* initialization */
/* TODO: better approach: construct a buffer queue and put all these
* NALs into the buffer. Wait until we are able to get any valid dts
* or such like, and dump the buffer and estimate the timestamps of
* the NALs by their duration.
*/
}
h264parse->cur_duration = duration;
h264parse->frame_cnt += 1;
if (outbuf_dts != GST_CLOCK_TIME_NONE)
h264parse->last_outbuf_dts = outbuf_dts;
}
if (outbuf_dts == GST_CLOCK_TIME_NONE)
outbuf_dts = h264parse->dts;
else
h264parse->dts = outbuf_dts;
TIMESTAMP_FINISH:
GST_BUFFER_TIMESTAMP (outbuf) = outbuf_dts;
GST_DEBUG_OBJECT (h264parse,
"pushing buffer %p, size %u, ts %" GST_TIME_FORMAT, outbuf,
@ -1164,7 +1285,6 @@ gst_h264_parse_chain_forward (GstH264Parse * h264parse, gboolean discont,
GST_BUFFER_FLAG_UNSET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
gst_buffer_set_caps (outbuf, GST_PAD_CAPS (h264parse->srcpad));
GST_BUFFER_TIMESTAMP (outbuf) = timestamp;
res = gst_pad_push (h264parse->srcpad, outbuf);
} else {
/* NALU can not be parsed yet, we wait for more data in the adapter. */