[FFmpeg-devel] [PATCH 2/3] avformat/mpegts: cache PID discard values

[Michael Niedermayer]

On Fri, Feb 01, 2019 at 10:29:13PM +0100, Marton Balint wrote:
> 
> 
> On Fri, 25 Jan 2019, Marton Balint wrote:
> 
> >
> >
> >On Fri, 25 Jan 2019, Michael Niedermayer wrote:
> >
> >>On Thu, Jan 24, 2019 at 09:38:00PM +0100, Marton Balint wrote:
> >>>discard_pid can be quite expensive, so let's cache it and recalculate
> >>>it
> >on
> >>>every packet start.
> >>>
> >>>ffmpeg -y -i samples/MPEG-VOB/sdtv/RAI.ts -c copy -map 0:v:0 -map
> >>>0:a:0 -f
> >mpegts /dev/null
> >>>
> >>>Before:
> >>>   1685 decicycles in handle_packet,  523483 runs,    805 skips
> >>>
> >>>After:
> >>>    883 decicycles in handle_packet,  523505 runs,    783 skips
> >>>
> >>>Signed-off-by: Marton Balint <cus at passwd.hu>
> >>>---
> >>> libavformat/mpegts.c | 7 +++++--
> >>> 1 file changed, 5 insertions(+), 2 deletions(-)
> >>>
> >>>diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
> >>>index 300db110d4..b04fd7b4f4 100644
> >>>--- a/libavformat/mpegts.c
> >>>+++ b/libavformat/mpegts.c
> >>>@@ -91,6 +91,7 @@ struct MpegTSFilter {
> >>>     int es_id;
> >>>     int last_cc; /* last cc code (-1 if first packet) */
> >>>     int64_t last_pcr;
> >>>+    int discard;
> >>>     enum MpegTSFilterType type;
> >>>     union {
> >>>         MpegTSPESFilter pes_filter;
> >>>@@ -2474,8 +2475,6 @@ static int handle_packet(MpegTSContext *ts,
> >>>const
> >uint8_t *packet)
> >>>     int64_t pos;
> >>>
> >>>     pid = AV_RB16(packet + 1) & 0x1fff;
> >>>-    if (pid && discard_pid(ts, pid))
> >>>-        return 0;
> >>>     is_start = packet[1] & 0x40;
> >>>     tss = ts->pids[pid];
> >>>     if (ts->auto_guess && !tss && is_start) {
> >>>@@ -2484,6 +2483,10 @@ static int handle_packet(MpegTSContext *ts,
> >>>const
> >uint8_t *packet)
> >>>     }
> >>>     if (!tss)
> >>>         return 0;
> >>>+    if (is_start)
> >>>+        tss->discard = discard_pid(ts, pid);
> >>>+    if (tss->discard)
> >>>+        return 0;
> >>
> >>this is moving the discard check over the auto_guess /add_pes_stream()
> >>have you checked or know that this is ok ?
> >>its not immedeatly obviouls (to me) why this would have no side effects
> >
> >As far as I see that code is used to add streams which are not part of the
> >detected programs. Therefore program discards should not concern them.
> 
> Will apply soon.

sure ok

thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I am the wisest man alive, for I know one thing, and that is that I know
nothing. -- Socrates
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