diff mbox series

[FFmpeg-devel,2/7] get_bits: support 32bits cache

Message ID 20200414102503.7858-3-christophe.gisquet@gmail.com
State New
Headers show
Series Port cache bitstream reader to 32bits, and improve | expand

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Commit Message

Christophe Gisquet April 14, 2020, 10:24 a.m. UTC 
Therefore, also activate it under ARCH_X86 (testing for more archs welcome)
for the only codecs supporting said cache reader.
For UTVideo, on 8 bits samples and ARCH_X86_32 (X86_64 being unaffected),
timings for one line do ~19.4k -> 15.1k and 16.5k (roughly 17% speedup).
---
 libavcodec/get_bits.h   | 110 ++++++++++++++++++++++++++++------------
 libavcodec/mvha.c       |   2 +-
 libavcodec/utvideodec.c |   2 +-
 3 files changed, 80 insertions(+), 34 deletions(-)

Comments

Carl Eugen Hoyos April 14, 2020, 10:41 p.m. UTC | #1 
Am Di., 14. Apr. 2020 um 12:25 Uhr schrieb Christophe Gisquet
<christophe.gisquet@gmail.com>:
>
> Therefore, also activate it under ARCH_X86 (testing for more archs welcome)
> for the only codecs supporting said cache reader.
> For UTVideo, on 8 bits samples and ARCH_X86_32 (X86_64 being unaffected),
> timings for one line do ~19.4k -> 15.1k and 16.5k

> (roughly 17% speedup).

I cannot reproduce - I see around 30% speedup on x86_32 decoding utvideo =-)

Will test on ppc32 over the weekend.

Carl Eugen
Christophe Gisquet April 15, 2020, 8:25 a.m. UTC | #2 
Hi,

Le mer. 15 avr. 2020 à 00:41, Carl Eugen Hoyos <ceffmpeg@gmail.com> a écrit :
> Will test on ppc32 over the weekend.

Please do. Testing on different endianness and different arch is
probably what this patchset lacks the most.

If you can, on this arch, please test just before and just after
"0006-get_bits-change-refill-to-RAD-pattern.patch"
The impact on x86 was non-trivial, but it may behave quite differently
(better?) on PPC.

Also, regarding the benchmarking, provided there is an encoder (either
in ffmpeg or VfW), I use a soft video, and another which is the soft
video with added grain/noise (see eg ffmpeg filter) added on top of
it.
As the bitstream reader gets faster, the difference in decoding speed
over the 2 may increase.

Thanks,
diff mbox series

Patch

diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h
index 66fb877599..cb4df98e54 100644
--- a/libavcodec/get_bits.h
+++ b/libavcodec/get_bits.h
@@ -58,10 +58,40 @@ 
 #define CACHED_BITSTREAM_READER 0
 #endif
 
+#if CACHED_BITSTREAM_READER
+
+# ifndef BITSTREAM_BITS
+#   if HAVE_FAST_64BIT || defined(LONG_BITSTREAM_READER)
+#     define BITSTREAM_BITS   64
+#   else
+#     define BITSTREAM_BITS   32
+#   endif
+# endif
+
+# if BITSTREAM_BITS == 64
+#   define BITSTREAM_HBITS  32
+typedef uint64_t cache_type;
+#   define AV_RB_ALL  AV_RB64
+#   define AV_RL_ALL  AV_RL64
+#   define AV_RB_HALF AV_RB32
+#   define AV_RL_HALF AV_RL32
+#   define CACHE_TYPE(a) UINT64_C(a)
+# else
+#   define BITSTREAM_HBITS  16
+typedef uint32_t cache_type;
+#   define AV_RB_ALL  AV_RB32
+#   define AV_RL_ALL  AV_RL32
+#   define AV_RB_HALF AV_RB16
+#   define AV_RL_HALF AV_RL16
+#   define CACHE_TYPE(a) UINT32_C(a)
+#endif
+
+#endif
+
 typedef struct GetBitContext {
     const uint8_t *buffer, *buffer_end;
 #if CACHED_BITSTREAM_READER
-    uint64_t cache;
+    cache_type cache;
     unsigned bits_left;
 #endif
     int index;
@@ -121,7 +151,11 @@  static inline unsigned int show_bits(GetBitContext *s, int n);
  */
 
 #if CACHED_BITSTREAM_READER
-#   define MIN_CACHE_BITS 64
+# if BITSTREAM_BITS == 32
+#   define MIN_CACHE_BITS (32-7)
+# else
+#   define MIN_CACHE_BITS  32
+# endif
 #elif defined LONG_BITSTREAM_READER
 #   define MIN_CACHE_BITS 32
 #else
@@ -226,22 +260,34 @@  static inline int get_bits_count(const GetBitContext *s)
 }
 
 #if CACHED_BITSTREAM_READER
-static inline void refill_32(GetBitContext *s, int is_le)
+static inline void refill_half(GetBitContext *s, int is_le)
 {
 #if !UNCHECKED_BITSTREAM_READER
     if (s->index >> 3 >= s->buffer_end - s->buffer)
         return;
 #endif
 
+#if BITSTREAM_BITS == 32
+    if (s->bits_left > 16) {
+        if (is_le)
+        s->cache |= (uint32_t)s->buffer[s->index >> 3] << s->bits_left;
+        else
+        s->cache |= (uint32_t)s->buffer[s->index >> 3] << (32 - s->bits_left);
+        s->index += 8;
+        s->bits_left += 8;
+        return;
+    }
+#endif
+
     if (is_le)
-        s->cache = (uint64_t)AV_RL32(s->buffer + (s->index >> 3)) << s->bits_left | s->cache;
+        s->cache |= (cache_type)AV_RL_HALF(s->buffer + (s->index >> 3)) << s->bits_left;
     else
-        s->cache = s->cache | (uint64_t)AV_RB32(s->buffer + (s->index >> 3)) << (32 - s->bits_left);
-    s->index     += 32;
-    s->bits_left += 32;
+        s->cache |= (cache_type)AV_RB_HALF(s->buffer + (s->index >> 3)) << (BITSTREAM_HBITS - s->bits_left);
+    s->index     += BITSTREAM_HBITS;
+    s->bits_left += BITSTREAM_HBITS;
 }
 
-static inline void refill_64(GetBitContext *s, int is_le)
+static inline void refill_all(GetBitContext *s, int is_le)
 {
 #if !UNCHECKED_BITSTREAM_READER
     if (s->index >> 3 >= s->buffer_end - s->buffer)
@@ -249,22 +295,22 @@  static inline void refill_64(GetBitContext *s, int is_le)
 #endif
 
     if (is_le)
-        s->cache = AV_RL64(s->buffer + (s->index >> 3));
+        s->cache = AV_RL_ALL(s->buffer + (s->index >> 3));
     else
-        s->cache = AV_RB64(s->buffer + (s->index >> 3));
-    s->index += 64;
-    s->bits_left = 64;
+        s->cache = AV_RB_ALL(s->buffer + (s->index >> 3));
+    s->index += BITSTREAM_BITS;
+    s->bits_left = BITSTREAM_BITS;
 }
 
-static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le)
+static inline cache_type get_val(GetBitContext *s, unsigned n, int is_le)
 {
-    uint64_t ret;
+    cache_type ret;
     av_assert2(n>0 && n<=63);
     if (is_le) {
-        ret = s->cache & ((UINT64_C(1) << n) - 1);
+        ret = s->cache & ((CACHE_TYPE(1) << n) - 1);
         s->cache >>= n;
     } else {
-        ret = s->cache >> (64 - n);
+        ret = s->cache >> (BITSTREAM_BITS - n);
         s->cache <<= n;
     }
     s->bits_left -= n;
@@ -274,12 +320,12 @@  static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le)
 static inline unsigned show_val(const GetBitContext *s, unsigned n)
 {
 #ifdef BITSTREAM_READER_LE
-    return s->cache & ((UINT64_C(1) << n) - 1);
+    return s->cache & ((CACHE_TYPE(1) << n) - 1);
 #else
-    return s->cache >> (64 - n);
+    return s->cache >> (BITSTREAM_BITS - n);
 #endif
 }
-#endif
+#endif // ~CACHED_BITSTREAM_READER
 
 /**
  * Skips the specified number of bits.
@@ -384,11 +430,11 @@  static inline unsigned int get_bits(GetBitContext *s, int n)
     av_assert2(n>0 && n<=32);
     if (n > s->bits_left) {
 #ifdef BITSTREAM_READER_LE
-        refill_32(s, 1);
+        refill_half(s, 1);
 #else
-        refill_32(s, 0);
+        refill_half(s, 0);
 #endif
-        if (s->bits_left < 32)
+        if (s->bits_left < BITSTREAM_HBITS)
             s->bits_left = n;
     }
 
@@ -422,8 +468,8 @@  static inline unsigned int get_bits_le(GetBitContext *s, int n)
 #if CACHED_BITSTREAM_READER
     av_assert2(n>0 && n<=32);
     if (n > s->bits_left) {
-        refill_32(s, 1);
-        if (s->bits_left < 32)
+        refill_half(s, 1);
+        if (s->bits_left < BITSTREAM_HBITS)
             s->bits_left = n;
     }
 
@@ -449,9 +495,9 @@  static inline unsigned int show_bits(GetBitContext *s, int n)
 #if CACHED_BITSTREAM_READER
     if (n > s->bits_left)
 #ifdef BITSTREAM_READER_LE
-        refill_32(s, 1);
+        refill_half(s, 1);
 #else
-        refill_32(s, 0);
+        refill_half(s, 0);
 #endif
 
     tmp = show_val(s, n);
@@ -474,16 +520,16 @@  static inline void skip_bits(GetBitContext *s, int n)
         s->cache = 0;
         s->bits_left = 0;
 
-        if (n >= 64) {
+        if (n >= BITSTREAM_BITS) {
             unsigned skip = (n / 8) * 8;
 
             n -= skip;
             s->index += skip;
         }
 #ifdef BITSTREAM_READER_LE
-        refill_64(s, 1);
+        refill_all(s, 1);
 #else
-        refill_64(s, 0);
+        refill_all(s, 0);
 #endif
         if (n)
             skip_remaining(s, n);
@@ -500,9 +546,9 @@  static inline unsigned int get_bits1(GetBitContext *s)
 #if CACHED_BITSTREAM_READER
     if (!s->bits_left)
 #ifdef BITSTREAM_READER_LE
-        refill_64(s, 1);
+        refill_all(s, 1);
 #else
-        refill_64(s, 0);
+        refill_all(s, 0);
 #endif
 
 #ifdef BITSTREAM_READER_LE
@@ -642,7 +688,7 @@  static inline int init_get_bits_xe(GetBitContext *s, const uint8_t *buffer,
 #if CACHED_BITSTREAM_READER
     s->cache              = 0;
     s->bits_left          = 0;
-    refill_64(s, is_le);
+    refill_all(s, is_le);
 #endif
 
     return ret;
diff --git a/libavcodec/mvha.c b/libavcodec/mvha.c
index c603ef6975..9d6dd9352a 100644
--- a/libavcodec/mvha.c
+++ b/libavcodec/mvha.c
@@ -24,7 +24,7 @@ 
 #include <stdlib.h>
 #include <string.h>
 
-#define CACHED_BITSTREAM_READER !ARCH_X86_32
+#define CACHED_BITSTREAM_READER ARCH_X86
 #include "libavutil/intreadwrite.h"
 
 #include "avcodec.h"
diff --git a/libavcodec/utvideodec.c b/libavcodec/utvideodec.c
index 4da257fc61..36dd661e90 100644
--- a/libavcodec/utvideodec.c
+++ b/libavcodec/utvideodec.c
@@ -27,7 +27,7 @@ 
 #include <inttypes.h>
 #include <stdlib.h>
 
-#define CACHED_BITSTREAM_READER !ARCH_X86_32
+#define CACHED_BITSTREAM_READER ARCH_X86
 #define UNCHECKED_BITSTREAM_READER 1
 
 #include "libavutil/intreadwrite.h"