virtualenv/FFmpeg
1
0
Fork 0
mirror of https://github.com/FFmpeg/FFmpeg.git synced 2025-01-13 21:28:01 +02:00
Code Issues Releases Activity

avcodec/magicyuv: Don't waste stack space

Browse Source 
Now that the HuffEntries are no longer sorted by the MagicYUV decoder,
their symbols are trivial: The symbol of the element with index i is i.
They can therefore be removed. Furthermore, despite the length of the
codes being in the range 1..32 bits, the actual value of the codes is
<= 4096 (for 12 bit content). The reason for this is that the longer
codes are on the left side of the tree, so that the higher bits of
these codes are simply zero. By using an uint16_t for the codes and
removing the symbols entry, the size of each HuffEntry is decreased from
eight to four, saving 16KB of stack space.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-09-23 16:50:02 +02:00
parent 1bf30a1beb
commit 116b235a0b
1 changed files with 5 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
libavcodec/magicyuv.c
View File

@ -46,9 +46,8 @@ typedef enum Prediction {
} Prediction;
typedef struct HuffEntry {
uint16_t sym;
uint8_t len;
uint32_t code;
uint16_t code;
} HuffEntry;
typedef struct MagicYUVContext {
@ -90,10 +89,9 @@ static int huff_build(HuffEntry he[], uint16_t codes_count[33],
he[i].code = codes_count[he[i].len];
codes_count[he[i].len]++;
}
return ff_init_vlc_sparse(vlc, FFMIN(max, 12), nb_elems,
&he[0].len, sizeof(he[0]), sizeof(he[0].len),
&he[0].code, sizeof(he[0]), sizeof(he[0].code),
&he[0].sym, sizeof(he[0]), sizeof(he[0].sym), 0);
return init_vlc(vlc, FFMIN(max, 12), nb_elems,
&he[0].len, sizeof(he[0]), sizeof(he[0].len),
&he[0].code, sizeof(he[0]), sizeof(he[0].code), 0);
}
static void magicyuv_median_pred16(uint16_t *dst, const uint16_t *src1,
@ -408,10 +406,8 @@ static int build_huffman(AVCodecContext *avctx, const uint8_t *table,
}
length_count[x] += l;
for (; j < k; j++) {
he[j].sym = j;
for (; j < k; j++)
he[j].len = x;
}
if (j == max) {
j = 0;