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ffmpeg: Maintain higher precision pts between video filter and fps code 

This is a bit ugly as it attempts to keep most of the computation
in integers before the double based fps code. The use of integers
is to reduce the chances of rounding differences between platforms

Previously the timestamp was rounded to the encoder timebase
before being converted back to double precision which could cause loss
of precision

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2015-01-16 17:03:35 +01:00
parent 261e8ccbd1
commit 7b32856011
2 changed files with 23 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
ffmpeg.c
View File

@ -883,14 +883,15 @@ static void do_subtitle_out(AVFormatContext *s,
static void do_video_out(AVFormatContext *s,
OutputStream *ost,
AVFrame *next_picture)
AVFrame *next_picture,
double sync_ipts)
{
int ret, format_video_sync;
AVPacket pkt;
AVCodecContext *enc = ost->enc_ctx;
AVCodecContext *mux_enc = ost->st->codec;
int nb_frames, nb0_frames, i;
double sync_ipts, delta, delta0;
double delta, delta0;
double duration = 0;
int frame_size = 0;
InputStream *ist = NULL;
@ -909,7 +910,6 @@ static void do_video_out(AVFormatContext *s,
duration = lrintf(av_frame_get_pkt_duration(next_picture) * av_q2d(ist->st->time_base) / av_q2d(enc->time_base));
}
sync_ipts = next_picture->pts;
delta0 = sync_ipts - ost->sync_opts;
delta = delta0 + duration;
@ -1233,6 +1233,7 @@ static int reap_filters(void)
filtered_frame = ost->filtered_frame;
while (1) {
double float_pts = AV_NOPTS_VALUE; // this is identical to filtered_frame.pts but with higher precission
ret = av_buffersink_get_frame_flags(filter, filtered_frame,
AV_BUFFERSINK_FLAG_NO_REQUEST);
if (ret < 0) {
@ -1246,9 +1247,19 @@ static int reap_filters(void)
av_frame_unref(filtered_frame);
continue;
}
if (filtered_frame->pts != AV_NOPTS_VALUE) {
int64_t start_time = (of->start_time == AV_NOPTS_VALUE) ? 0 : of->start_time;
AVRational tb = enc->time_base;
int extra_bits = av_clip(29 - av_log2(tb.den), 0, 16);
tb.den <<= extra_bits;
float_pts =
av_rescale_q(filtered_frame->pts, filter->inputs[0]->time_base, tb) -
av_rescale_q(start_time, AV_TIME_BASE_Q, tb);
float_pts /= 1 << extra_bits;
// avoid exact midoints to reduce the chance of rounding differences, this can be removed in case the fps code is changed to work with integers
float_pts += FFSIGN(float_pts) * 1.0 / (1<<17);
filtered_frame->pts =
av_rescale_q(filtered_frame->pts, filter->inputs[0]->time_base, enc->time_base) -
av_rescale_q(start_time, AV_TIME_BASE_Q, enc->time_base);
@ -1262,12 +1273,13 @@ static int reap_filters(void)
enc->sample_aspect_ratio = filtered_frame->sample_aspect_ratio;
if (debug_ts) {
av_log(NULL, AV_LOG_INFO, "filter -> pts:%s pts_time:%s time_base:%d/%d\n",
av_log(NULL, AV_LOG_INFO, "filter -> pts:%s pts_time:%s exact:%f time_base:%d/%d\n",
av_ts2str(filtered_frame->pts), av_ts2timestr(filtered_frame->pts, &enc->time_base),
float_pts,
enc->time_base.num, enc->time_base.den);
}
do_video_out(of->ctx, ost, filtered_frame);
do_video_out(of->ctx, ost, filtered_frame, float_pts);
break;
case AVMEDIA_TYPE_AUDIO:
if (!(enc->codec->capabilities & CODEC_CAP_PARAM_CHANGE) &&

10
tests/ref/fate/filter-setpts
View File

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