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avcodec/sanm: codec31/32 support

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codec31/32 are similar to codec1/3 (RLE coding) but with two 4-bit pixels
per byte; they are only used in the Sega-CD release of Rebel Assault 1.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
This commit is contained in:
Manuel Lauss
2025-05-30 13:10:47 +02:00
parent b7662ddd15
commit d9797544b4
1 changed files with 59 additions and 0 deletions
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59
libavcodec/sanm.c
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@ -909,6 +909,62 @@ static int old_codec1(SANMVideoContext *ctx, GetByteContext *gb, int top,
return 0;
}
static int old_codec31(SANMVideoContext *ctx, GetByteContext *gb, int top,
int left, int width, int height, int p1, int opaque)
{
int i, j, len, flag, code, val, end, pxoff;
const int maxpxo = ctx->height * ctx->pitch;
uint8_t *dst = (uint8_t *)ctx->fbuf;
for (i = 0; i < height; i++) {
if (bytestream2_get_bytes_left(gb) < 2)
return AVERROR_INVALIDDATA;
len = bytestream2_get_le16u(gb);
end = bytestream2_tell(gb) + len;
pxoff = left + ((top + i) * ctx->pitch);
while (bytestream2_tell(gb) < end) {
if (bytestream2_get_bytes_left(gb) < 2)
return AVERROR_INVALIDDATA;
code = bytestream2_get_byteu(gb);
flag = code & 1;
code = (code >> 1) + 1;
if (flag) {
val = bytestream2_get_byteu(gb);
for (j = 0; j < code; j++) {
if ((0 != (val & 0xf)) || opaque) {
if (pxoff >= 0 && pxoff < maxpxo)
*(dst + pxoff) = p1 + (val & 0xf);
}
pxoff++;
if ((0 != (val >> 4)) || opaque) {
if (pxoff >= 0 && pxoff < maxpxo)
*(dst + pxoff) = p1 + (val >> 4);
}
pxoff++;
}
} else {
if (bytestream2_get_bytes_left(gb) < code)
return AVERROR_INVALIDDATA;
for (j = 0; j < code; j++) {
val = bytestream2_get_byteu(gb);
if ((pxoff >= 0) && (pxoff < maxpxo) && ((0 != (val & 0xf)) || opaque))
*(dst + pxoff) = p1 + (val & 0xf);
pxoff++;
if ((pxoff >= 0) && (pxoff < maxpxo) && ((0 != (val >> 4)) || opaque))
*(dst + pxoff) = p1 + (val >> 4);
pxoff++;
}
}
}
}
ctx->rotate_code = 0;
return 0;
}
static int old_codec2(SANMVideoContext *ctx, GetByteContext *gb, int top,
int left, int width, int height)
{
@ -1689,6 +1745,9 @@ static int process_frame_obj(SANMVideoContext *ctx, GetByteContext *gb)
return old_codec21(ctx, gb, top, left, w, h);
case 23:
return old_codec23(ctx, gb, top, left, w, h, param, parm2);
case 31:
case 32:
return old_codec31(ctx, gb, top, left, w, h, param, (codec == 32));
case 37:
ret = old_codec37(ctx, w, h); break;
case 45: