diff options
| author | Ben Avison <bavison@riscosopen.org> | 2013-08-05 13:12:49 +0100 |
|---|---|---|
| committer | popcornmix <popcornmix@gmail.com> | 2013-08-07 21:45:00 +0100 |
| commit | 45b07141ab2d33092811bb912070212ba816daf0 (patch) | |
| tree | 07c09d75a831cababc9ad9e163f75439a196435c /lib | |
| parent | 6aec5772fd5331b3514f308ab0895f6234b60045 (diff) | |
[ffmpeg] - backport - mpegts: Remove one 64-bit integer modulus operation per packet
The common case of the pointer having increased by one packet (which results
in no change to the modulus) can be detected with a 64-bit subtraction,
which is far cheaper than a division on many platforms.
Before After
Mean StdDev Mean StdDev Change
Divisions 248.3 8.8 51.5 7.4 +381.7%
Overall 2773.2 25.6 2372.5 43.1 +16.9%
Signed-off-by: Martin Storsjö <martin@martin.st>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/ffmpeg/libavcodec/mathops.h | 9 | ||||
| -rw-r--r-- | lib/ffmpeg/libavformat/mpegts.c | 5 |
2 files changed, 13 insertions, 1 deletions
diff --git a/lib/ffmpeg/libavcodec/mathops.h b/lib/ffmpeg/libavcodec/mathops.h index 592f5a5e75..1d573424f4 100644 --- a/lib/ffmpeg/libavcodec/mathops.h +++ b/lib/ffmpeg/libavcodec/mathops.h @@ -195,6 +195,15 @@ if ((y) < (x)) {\ # define FASTDIV(a,b) ((uint32_t)((((uint64_t)a) * ff_inverse[b]) >> 32)) #endif /* FASTDIV */ +#ifndef MOD_UNLIKELY +# define MOD_UNLIKELY(modulus, dividend, divisor, prev_dividend) \ + do { \ + if ((prev_dividend) == 0 || (dividend) - (prev_dividend) != (divisor)) \ + (modulus) = (dividend) % (divisor); \ + (prev_dividend) = (dividend); \ + } while (0) +#endif + static inline av_const unsigned int ff_sqrt(unsigned int a) { unsigned int b; diff --git a/lib/ffmpeg/libavformat/mpegts.c b/lib/ffmpeg/libavformat/mpegts.c index 82dd209860..b995f60fd4 100644 --- a/lib/ffmpeg/libavformat/mpegts.c +++ b/lib/ffmpeg/libavformat/mpegts.c @@ -28,6 +28,7 @@ #include "libavutil/avassert.h" #include "libavcodec/bytestream.h" #include "libavcodec/get_bits.h" +#include "libavcodec/mathops.h" #include "avformat.h" #include "mpegts.h" #include "internal.h" @@ -99,6 +100,8 @@ struct MpegTSContext { int raw_packet_size; int pos47; + /** position corresponding to pos47, or 0 if pos47 invalid */ + int64_t pos; /** if true, all pids are analyzed to find streams */ int auto_guess; @@ -1814,7 +1817,7 @@ static int handle_packet(MpegTSContext *ts, const uint8_t *packet) return 0; pos = avio_tell(ts->stream->pb); - ts->pos47= pos % ts->raw_packet_size; + MOD_UNLIKELY(ts->pos47, pos, ts->raw_packet_size, ts->pos); if (tss->type == MPEGTS_SECTION) { if (is_start) { |