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mpeg2enc: report a latency

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Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1491>
This commit is contained in:
Mathieu Duponchelle 2020-08-04 16:05:55 +02:00 committed by GStreamer Merge Bot
parent 2dfceac9fc
commit 674ad01016
1 changed files with 26 additions and 0 deletions
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26
ext/mpeg2enc/gstmpeg2enc.cc
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@ -559,12 +559,38 @@ gst_mpeg2enc_loop (GstVideoEncoder * video_encoder)
if (!enc->encoder) { if (!enc->encoder) {
gboolean ret; gboolean ret;
GstClockTime latency;
GstVideoInfo *info = &enc->input_state->info;
/* create new encoder with these settings */ /* create new encoder with these settings */
enc->encoder = new GstMpeg2Encoder (enc->options, GST_ELEMENT (video_encoder), enc->encoder = new GstMpeg2Encoder (enc->options, GST_ELEMENT (video_encoder),
gst_pad_get_current_caps(video_encoder->sinkpad)); gst_pad_get_current_caps(video_encoder->sinkpad));
ret = enc->encoder->setup (); ret = enc->encoder->setup ();
/* We must have a fixated max GOP size after setting up */
g_assert (enc->options->max_GOP_size != -1);
/* mjpeg tools outputs encoded data on a GOP basis, our latency is
* thus at least max_GOP_size. It also introduces a 5-frame delay on
* top of that, this was determined empirically, a surface level inspection
* of the code didn't show where and why that delay is introduced exactly,
* and this is not specifically documented, but it needs to be taken
* into account when calculating the latency
*/
if (GST_VIDEO_INFO_FPS_D (info) == 0 || GST_VIDEO_INFO_FPS_N (info) == 0) {
/* Assume 25fps for unknown framerates. Better than reporting
* that we introduce no latency while we actually do
*/
latency = gst_util_uint64_scale (enc->options->max_GOP_size + 5,
1 * GST_SECOND, 25);
} else {
latency = gst_util_uint64_scale (enc->options->max_GOP_size + 5,
GST_VIDEO_INFO_FPS_D (info) * GST_SECOND, GST_VIDEO_INFO_FPS_N (info));
}
gst_video_encoder_set_latency (video_encoder, latency, latency);
/* SeqEncoder init requires at least two frames */ /* SeqEncoder init requires at least two frames */
enc->encoder->init (); enc->encoder->init ();