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videodecoder: refactor and document finish_frame some more

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* Move the in-flight iteration and handling code into the main block
* Document the intent a bit more

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4694>
This commit is contained in:
Edward Hervey 2023-05-07 09:27:16 +02:00 committed by GStreamer Marge Bot
parent bce9f3327d
commit 386a8dbae5
1 changed files with 82 additions and 77 deletions
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159
subprojects/gst-plugins-base/gst-libs/gst/video/gstvideodecoder.c
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@ -2976,7 +2976,9 @@ gst_video_decoder_prepare_finish_frame (GstVideoDecoder *
{ {
GstVideoDecoderPrivate *priv = decoder->priv; GstVideoDecoderPrivate *priv = decoder->priv;
GList *l, *events = NULL; GList *l, *events = NULL;
gboolean sync; gboolean sync, frames_without_dts, frames_without_pts;
GstClockTime min_dts, min_pts;
GstVideoCodecFrame *earliest_dts_frame, *earliest_pts_frame;
#ifndef GST_DISABLE_GST_DEBUG #ifndef GST_DISABLE_GST_DEBUG
GST_LOG_OBJECT (decoder, "n %d in %" G_GSIZE_FORMAT " out %" G_GSIZE_FORMAT, GST_LOG_OBJECT (decoder, "n %d in %" G_GSIZE_FORMAT " out %" G_GSIZE_FORMAT,
@ -3046,79 +3048,84 @@ gst_video_decoder_prepare_finish_frame (GstVideoDecoder *
GST_TIME_ARGS (frame->duration)); GST_TIME_ARGS (frame->duration));
} }
/* PTS is expected monotone ascending, /* The following code is to fix issues with PTS and DTS:
* so a good guess is lowest unsent DTS */ * * Because the input PTS and/or DTS was mis-used (using DTS as PTS, or PTS
{ * as DTS)
GstClockTime min_dts = GST_CLOCK_TIME_NONE; * * Because the input was missing PTS and/or DTS
GstClockTime min_pts = GST_CLOCK_TIME_NONE; *
GstVideoCodecFrame *earliest_dts_frame = NULL; * For that, we will collected 3 important information from the frames in
GstVideoCodecFrame *earliest_pts_frame = NULL; * flight:
gboolean frames_without_dts = FALSE; * * Whether all frames had a valid PTS or a valid DTS
gboolean frames_without_pts = FALSE; * * Which frame has the lowest PTS (and its value)
* * Which frame has the lowest DTS (And its value)
*/
frames_without_pts = frames_without_dts = FALSE;
min_dts = min_pts = GST_CLOCK_TIME_NONE;
earliest_pts_frame = earliest_dts_frame = NULL;
/* Check what is the earliest PTS and DTS in our pendings frames */ /* Check what is the earliest PTS and DTS in our pendings frames */
for (l = priv->frames.head; l; l = l->next) { for (l = priv->frames.head; l; l = l->next) {
GstVideoCodecFrame *tmp = l->data; GstVideoCodecFrame *tmp = l->data;
/* ABI.ts contains DTS */ /* ABI.ts contains DTS */
if (!GST_CLOCK_TIME_IS_VALID (tmp->abidata.ABI.ts)) { if (!GST_CLOCK_TIME_IS_VALID (tmp->abidata.ABI.ts)) {
frames_without_dts = TRUE; frames_without_dts = TRUE;
} else if (!GST_CLOCK_TIME_IS_VALID (min_dts) } else if (!GST_CLOCK_TIME_IS_VALID (min_dts)
|| tmp->abidata.ABI.ts < min_dts) { || tmp->abidata.ABI.ts < min_dts) {
min_dts = tmp->abidata.ABI.ts; min_dts = tmp->abidata.ABI.ts;
earliest_dts_frame = tmp; earliest_dts_frame = tmp;
}
/* ABI.ts2 contains PTS */
if (!GST_CLOCK_TIME_IS_VALID (tmp->abidata.ABI.ts2)) {
frames_without_pts = TRUE;
} else if (!GST_CLOCK_TIME_IS_VALID (min_pts)
|| tmp->abidata.ABI.ts2 < min_pts) {
min_pts = tmp->abidata.ABI.ts2;
earliest_pts_frame = tmp;
}
}
/* save dts if needed */
if (earliest_dts_frame && earliest_dts_frame != frame) {
earliest_dts_frame->abidata.ABI.ts = frame->abidata.ABI.ts;
}
/* save pts if needed */
if (earliest_pts_frame && earliest_pts_frame != frame) {
earliest_pts_frame->abidata.ABI.ts2 = frame->abidata.ABI.ts2;
} }
/* and set if needed; /* ABI.ts2 contains PTS */
* valid delta means we have reasonable DTS input */ if (!GST_CLOCK_TIME_IS_VALID (tmp->abidata.ABI.ts2)) {
/* also, if we ended up reordered, means this approach is conflicting frames_without_pts = TRUE;
* with some sparse existing PTS, and so it does not work out */ } else if (!GST_CLOCK_TIME_IS_VALID (min_pts)
if (!priv->reordered_output && || tmp->abidata.ABI.ts2 < min_pts) {
!GST_CLOCK_TIME_IS_VALID (frame->pts) && !frames_without_dts && min_pts = tmp->abidata.ABI.ts2;
GST_CLOCK_TIME_IS_VALID (priv->pts_delta)) { earliest_pts_frame = tmp;
frame->pts = min_dts + priv->pts_delta;
GST_DEBUG_OBJECT (decoder,
"no valid PTS, using oldest DTS %" GST_TIME_FORMAT,
GST_TIME_ARGS (frame->pts));
}
}
/* if we detected reordered output, then PTS are void,
* however those were obtained; bogus input, subclass etc */
if (priv->reordered_output && !frames_without_pts) {
GST_DEBUG_OBJECT (decoder, "invalidating PTS");
frame->pts = GST_CLOCK_TIME_NONE;
}
/* If the frame doesn't have a PTS we can take the earliest PTS from our
* pending frame list (Only valid if all pending frames have PTS) */
if (!GST_CLOCK_TIME_IS_VALID (frame->pts) && !frames_without_pts) {
frame->pts = min_pts;
GST_DEBUG_OBJECT (decoder,
"no valid PTS, using oldest PTS %" GST_TIME_FORMAT,
GST_TIME_ARGS (frame->pts));
} }
} }
/* save dts if needed */
if (earliest_dts_frame && earliest_dts_frame != frame) {
earliest_dts_frame->abidata.ABI.ts = frame->abidata.ABI.ts;
}
/* save pts if needed */
if (earliest_pts_frame && earliest_pts_frame != frame) {
earliest_pts_frame->abidata.ABI.ts2 = frame->abidata.ABI.ts2;
}
/* First attempt at recovering missing PTS:
* * If we figured out the PTS<->DTS delta (from a keyframe)
* * AND all frames have a valid DTS (i.e. it is not sparsely timestamped
* input)
* * AND we are not dealing with ordering issues
*
* We can figure out the pts from the lowest DTS and the PTS<->DTS delta
*/
if (!priv->reordered_output &&
!GST_CLOCK_TIME_IS_VALID (frame->pts) && !frames_without_dts &&
GST_CLOCK_TIME_IS_VALID (priv->pts_delta)) {
frame->pts = min_dts + priv->pts_delta;
GST_DEBUG_OBJECT (decoder,
"no valid PTS, using oldest DTS %" GST_TIME_FORMAT,
GST_TIME_ARGS (frame->pts));
}
/* if we detected reordered output, then PTS are void, however those were
* obtained; bogus input, subclass etc */
if (priv->reordered_output && !frames_without_pts) {
GST_DEBUG_OBJECT (decoder, "invalidating PTS");
frame->pts = GST_CLOCK_TIME_NONE;
}
/* If the frame doesn't have a PTS we can take the earliest PTS from our
* pending frame list (Only valid if all pending frames have PTS) */
if (!GST_CLOCK_TIME_IS_VALID (frame->pts) && !frames_without_pts) {
frame->pts = min_pts;
GST_DEBUG_OBJECT (decoder,
"no valid PTS, using oldest PTS %" GST_TIME_FORMAT,
GST_TIME_ARGS (frame->pts));
}
if (frame->pts == GST_CLOCK_TIME_NONE) { if (frame->pts == GST_CLOCK_TIME_NONE) {
/* Last ditch timestamp guess: Just add the duration to the previous /* Last ditch timestamp guess: Just add the duration to the previous
@ -3145,16 +3152,14 @@ gst_video_decoder_prepare_finish_frame (GstVideoDecoder *
} }
} }
if (GST_CLOCK_TIME_IS_VALID (priv->last_timestamp_out)) { if (GST_CLOCK_TIME_IS_VALID (priv->last_timestamp_out) &&
if (frame->pts < priv->last_timestamp_out) { frame->pts < priv->last_timestamp_out) {
GST_WARNING_OBJECT (decoder, GST_WARNING_OBJECT (decoder,
"decreasing timestamp (%" GST_TIME_FORMAT " < %" "decreasing timestamp (%" GST_TIME_FORMAT " < %" GST_TIME_FORMAT ")",
GST_TIME_FORMAT ")", GST_TIME_ARGS (frame->pts), GST_TIME_ARGS (priv->last_timestamp_out));
GST_TIME_ARGS (frame->pts), GST_TIME_ARGS (priv->last_timestamp_out)); priv->reordered_output = TRUE;
priv->reordered_output = TRUE; /* make it a bit less weird downstream */
/* make it a bit less weird downstream */ frame->pts = priv->last_timestamp_out;
frame->pts = priv->last_timestamp_out;
}
} }
if (GST_CLOCK_TIME_IS_VALID (frame->pts)) if (GST_CLOCK_TIME_IS_VALID (frame->pts))