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avviddec: improve latency calculation

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When thread_type is set to FF_THREAD_FRAME, per the documentation
a latency of one frame per thread is introduced:

<https://ffmpeg.org/ffmpeg-codecs.html>, search for thread_type.

Additionally, we need in that case to calculate the automatic
number of threads ourselves, so as to accurately calculate the
latency.
This commit is contained in:
Mathieu Duponchelle 2019-07-18 00:20:16 +02:00
parent e8f21b510a
commit 1e8e040fbc
1 changed files with 22 additions and 8 deletions
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30
ext/libav/gstavviddec.c
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@ -518,14 +518,6 @@ gst_ffmpegviddec_set_format (GstVideoDecoder * decoder,
* supports it) */
ffmpegdec->context->debug_mv = ffmpegdec->debug_mv;
if (ffmpegdec->max_threads == 0) {
if (!(oclass->in_plugin->capabilities & AV_CODEC_CAP_AUTO_THREADS))
ffmpegdec->context->thread_count = gst_ffmpeg_auto_max_threads ();
else
ffmpegdec->context->thread_count = 0;
} else
ffmpegdec->context->thread_count = ffmpegdec->max_threads;
if (ffmpegdec->thread_type) {
GST_DEBUG_OBJECT (ffmpegdec, "Use requested thread type 0x%x",
ffmpegdec->thread_type);
@ -549,6 +541,17 @@ gst_ffmpegviddec_set_format (GstVideoDecoder * decoder,
ffmpegdec->context->thread_type = FF_THREAD_SLICE | FF_THREAD_FRAME;
}
if (ffmpegdec->max_threads == 0) {
/* When thread type is FF_THREAD_FRAME, extra latency is introduced equal
* to one frame per thread. We thus need to calculate the thread count ourselves */
if ((!(oclass->in_plugin->capabilities & AV_CODEC_CAP_AUTO_THREADS)) ||
(ffmpegdec->context->thread_type & FF_THREAD_FRAME))
ffmpegdec->context->thread_count = gst_ffmpeg_auto_max_threads ();
else
ffmpegdec->context->thread_count = 0;
} else
ffmpegdec->context->thread_count = ffmpegdec->max_threads;
/* open codec - we don't select an output pix_fmt yet,
* simply because we don't know! We only get it
* during playback... */
@ -564,6 +567,12 @@ gst_ffmpegviddec_set_format (GstVideoDecoder * decoder,
latency = gst_util_uint64_scale_ceil (
(ffmpegdec->context->has_b_frames) * GST_SECOND, info->fps_d,
info->fps_n);
if (ffmpegdec->context->thread_type & FF_THREAD_FRAME) {
latency +=
gst_util_uint64_scale_ceil (ffmpegdec->context->thread_count *
GST_SECOND, info->fps_d, info->fps_n);
}
}
ret = TRUE;
@ -1431,6 +1440,11 @@ gst_ffmpegviddec_negotiate (GstFFMpegVidDec * ffmpegdec,
latency =
gst_util_uint64_scale_ceil (ffmpegdec->context->has_b_frames *
GST_SECOND, fps_d, fps_n);
if (ffmpegdec->context->thread_type & FF_THREAD_FRAME) {
latency +=
gst_util_uint64_scale_ceil (ffmpegdec->context->thread_count *
GST_SECOND, fps_d, fps_n);
}
gst_video_decoder_set_latency (GST_VIDEO_DECODER (ffmpegdec), latency,
latency);
}