[FFmpeg-devel] [PATCH 1/6] avcodec/mpegvideodata: Make DC scale tables smaller

[Andreas Rheinhardt]

These tables are only accessed in ff_set_qscale()
which only accesses values 1..31 as well as in
encode_picture() in mpegvideo_enc.c, accessing
the value with index 8. So make these tables smaller.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
---
 libavcodec/mpegvideodata.c | 32 ++++----------------------------
 libavcodec/mpegvideodata.h |  2 +-
 2 files changed, 5 insertions(+), 29 deletions(-)

diff --git a/libavcodec/mpegvideodata.c b/libavcodec/mpegvideodata.c
index da0638e052..b98e90cf43 100644
--- a/libavcodec/mpegvideodata.c
+++ b/libavcodec/mpegvideodata.c
@@ -30,46 +30,22 @@ const uint8_t ff_mpeg2_non_linear_qscale[32] = {
     56, 64, 72, 80, 88, 96, 104, 112,
 };
 
-const uint8_t ff_mpeg1_dc_scale_table[128] = {
-    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-    8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+const uint8_t ff_mpeg1_dc_scale_table[32] = {
     8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
     8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
 };
 
-static const uint8_t mpeg2_dc_scale_table1[128] = {
-    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+static const uint8_t mpeg2_dc_scale_table1[32] = {
     4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
     4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
 };
 
-static const uint8_t mpeg2_dc_scale_table2[128] = {
-    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+static const uint8_t mpeg2_dc_scale_table2[32] = {
     2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
     2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
 };
 
-static const uint8_t mpeg2_dc_scale_table3[128] = {
-    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+static const uint8_t mpeg2_dc_scale_table3[32] = {
     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 };
diff --git a/libavcodec/mpegvideodata.h b/libavcodec/mpegvideodata.h
index 14f4806d66..cf783ef31c 100644
--- a/libavcodec/mpegvideodata.h
+++ b/libavcodec/mpegvideodata.h
@@ -25,7 +25,7 @@
 extern const uint8_t ff_alternate_horizontal_scan[64];
 extern const uint8_t ff_alternate_vertical_scan[64];
 
-extern const uint8_t ff_mpeg1_dc_scale_table[128];
+extern const uint8_t ff_mpeg1_dc_scale_table[32];
 extern const uint8_t * const ff_mpeg2_dc_scale_table[4];
 
 extern const uint8_t ff_mpeg2_non_linear_qscale[32];
-- 
2.34.1