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authorSteinar H. Gunderson <steinar+ffmpeg@gunderson.no>2020-07-18 16:53:03 +0200
committerMichael Niedermayer <michael@niedermayer.cc>2020-07-19 10:59:43 +0200
commit88d80cb97528d52dac3178cf5393d6095eca6200 (patch)
tree2a8870073dce921e6aa0f10a72da580e206a9a54
parentc63c303a1f2b58677d480505ec93a90f77dd25b5 (diff)
downloadffmpeg-88d80cb97528d52dac3178cf5393d6095eca6200.tar.gz
avcodec/put_bits: Make bit buffers 64-bit
Change BitBuf into uint64_t on 64-bit x86. This means we need to flush the buffer less often, which is a significant speed win. All other platforms, including all 32-bit ones, are unchanged. Output bitstream is the same. All API constraints are kept in place, e.g., you still cannot put_bits() more than 31 bits at a time. This is so that codecs cannot accidentally become 64-bit-only or similar. Benchmarking on transcoding to various formats shows consistently positive results: dnxhd 25.60 fps -> 26.26 fps ( +2.6%) dvvideo 24.88 fps -> 25.17 fps ( +1.2%) ffv1 14.32 fps -> 14.58 fps ( +1.8%) huffyuv 58.75 fps -> 63.27 fps ( +7.7%) jpegls 6.22 fps -> 6.34 fps ( +1.8%) magicyuv 57.10 fps -> 63.29 fps (+10.8%) mjpeg 48.65 fps -> 49.01 fps ( +0.7%) mpeg1video 76.41 fps -> 77.01 fps ( +0.8%) mpeg2video 75.99 fps -> 77.43 fps ( +1.9%) mpeg4 80.66 fps -> 81.37 fps ( +0.9%) prores 12.35 fps -> 12.88 fps ( +4.3%) prores_ks 16.20 fps -> 16.80 fps ( +3.7%) rv20 62.80 fps -> 62.99 fps ( +0.3%) utvideo 68.41 fps -> 76.32 fps (+11.6%) Note that this includes video decoding and all other encoding work, such as DCTs. If you isolate the actual bit-writing routines, it is likely to be much more. Benchmark details: Transcoding the first 30 seconds of Big Buck Bunny in 1080p, Haswell 2.1 GHz, GCC 8.3, generally quantizer locked to 5.0. (Exceptions: DNxHD needs fixed bitrate, and JPEG-LS is so slow that I only took the first 10 seconds, not 30.) All runs were done ten times and single-threaded, top and bottom two results discarded to get rid of outliers, arithmetic mean between the remaining six. Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
-rw-r--r--libavcodec/asvenc.c1
-rw-r--r--libavcodec/put_bits.h31
2 files changed, 25 insertions, 7 deletions
diff --git a/libavcodec/asvenc.c b/libavcodec/asvenc.c
index c2c940f365..28f7a94071 100644
--- a/libavcodec/asvenc.c
+++ b/libavcodec/asvenc.c
@@ -295,6 +295,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
while (put_bits_count(&a->pb) & 31)
put_bits(&a->pb, 8, 0);
+ flush_put_bits(&a->pb);
size = put_bits_count(&a->pb) / 32;
if (avctx->codec_id == AV_CODEC_ID_ASV1) {
diff --git a/libavcodec/put_bits.h b/libavcodec/put_bits.h
index c6a8f3ac14..ddd97906b2 100644
--- a/libavcodec/put_bits.h
+++ b/libavcodec/put_bits.h
@@ -29,12 +29,20 @@
#include <stdint.h>
#include <stddef.h>
+#include "config.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/avassert.h"
+#if ARCH_X86_64
+// TODO: Benchmark and optionally enable on other 64-bit architectures.
+typedef uint64_t BitBuf;
+#define AV_WBBUF AV_WB64
+#define AV_WLBUF AV_WL64
+#else
typedef uint32_t BitBuf;
#define AV_WBBUF AV_WB32
#define AV_WLBUF AV_WL32
+#endif
static const int BUF_BITS = 8 * sizeof(BitBuf);
@@ -163,17 +171,11 @@ void avpriv_put_string(PutBitContext *pb, const char *string,
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
#endif
-/**
- * Write up to 31 bits into a bitstream.
- * Use put_bits32 to write 32 bits.
- */
-static inline void put_bits(PutBitContext *s, int n, BitBuf value)
+static inline void put_bits_no_assert(PutBitContext *s, int n, BitBuf value)
{
BitBuf bit_buf;
int bit_left;
- av_assert2(n <= 31 && value < (1UL << n));
-
bit_buf = s->bit_buf;
bit_left = s->bit_left;
@@ -215,6 +217,16 @@ static inline void put_bits(PutBitContext *s, int n, BitBuf value)
s->bit_left = bit_left;
}
+/**
+ * Write up to 31 bits into a bitstream.
+ * Use put_bits32 to write 32 bits.
+ */
+static inline void put_bits(PutBitContext *s, int n, BitBuf value)
+{
+ av_assert2(n <= 31 && value < (1UL << n));
+ put_bits_no_assert(s, n, value);
+}
+
static inline void put_bits_le(PutBitContext *s, int n, BitBuf value)
{
BitBuf bit_buf;
@@ -258,6 +270,11 @@ static void av_unused put_bits32(PutBitContext *s, uint32_t value)
BitBuf bit_buf;
int bit_left;
+ if (BUF_BITS > 32) {
+ put_bits_no_assert(s, 32, value);
+ return;
+ }
+
bit_buf = s->bit_buf;
bit_left = s->bit_left;