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libavcodec/sanm: add codec47 interpolation table support

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Some codec47 frames come with an interpolation table:
Combining 2 adjacent pixels into a 16bit value, this value can
then be used as index into the interpolation table to get a new
pixel value.  This is used for subcodec 1, which encodes a key-
frame at half width and height, and makes these frame less blocky
appearing.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Manuel Lauss 2024-11-08 09:55:03 +01:00 committed by Anton Khirnov
parent 44d32c8a23
commit 1e2a72ae1d
1 changed files with 56 additions and 11 deletions
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67
libavcodec/sanm.c
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@ -291,6 +291,7 @@ typedef struct SANMVideoContext {
int8_t p4x4glyphs[NGLYPHS][16];
int8_t p8x8glyphs[NGLYPHS][64];
uint8_t c47itbl[0x10000];
} SANMVideoContext;
typedef struct SANMFrameHeader {
@ -856,6 +857,55 @@ static int process_block(SANMVideoContext *ctx, uint8_t *dst, uint8_t *prev1,
return 0;
}
static void codec47_read_interptable(SANMVideoContext *ctx)
{
uint8_t *p1, *p2, *itbl = ctx->c47itbl;
int i, j;
for (i = 0; i < 256; i++) {
p1 = p2 = itbl + i;
for (j = 256 - i; j; j--) {
*p1 = *p2 = bytestream2_get_byte(&ctx->gb);
p1 += 1;
p2 += 256;
}
itbl += 256;
}
}
static void codec47_comp1(SANMVideoContext *ctx, uint8_t *dst_in, int width,
int height, ptrdiff_t stride)
{
uint8_t p1, *dst, *itbl = ctx->c47itbl;
uint16_t px;
int i, j;
dst = dst_in + stride;
for (i = 0; i < height; i += 2) {
p1 = bytestream2_get_byte(&ctx->gb);
*dst++ = p1;
*dst++ = p1;
px = p1;
for (j = 2; j < width; j += 2) {
p1 = bytestream2_get_byte(&ctx->gb);
px = (px << 8) | p1;
*dst++ = itbl[px];
*dst++ = p1;
}
dst += stride;
}
memcpy(dst_in, dst_in + stride, width);
dst = dst_in + stride + stride;
for (i = 2; i < height - 1; i += 2) {
for (j = 0; j < width; j++) {
px = (*(dst - stride) << 8) | *(dst + stride);
*dst++ = itbl[px];
}
dst += stride;
}
}
static int old_codec47(SANMVideoContext *ctx, int top,
int left, int width, int height)
{
@ -880,8 +930,11 @@ static int old_codec47(SANMVideoContext *ctx, int top,
av_log(ctx->avctx, AV_LOG_WARNING, "Decoded size is too large.\n");
}
if (skip & 1)
bytestream2_skip(&ctx->gb, 0x8080);
if (skip & 1) {
if (bytestream2_get_bytes_left(&ctx->gb) < 0x8080)
return AVERROR_INVALIDDATA;
codec47_read_interptable(ctx);
}
if (!seq) {
ctx->prev_seq = -1;
memset(prev1, 0, ctx->height * stride);
@ -900,15 +953,7 @@ static int old_codec47(SANMVideoContext *ctx, int top,
case 1:
if (bytestream2_get_bytes_left(&ctx->gb) < ((width + 1) >> 1) * ((height + 1) >> 1))
return AVERROR_INVALIDDATA;
for (j = 0; j < height; j += 2) {
for (i = 0; i < width; i += 2) {
dst[i] =
dst[i + 1] =
dst[stride + i] =
dst[stride + i + 1] = bytestream2_get_byteu(&ctx->gb);
}
dst += stride * 2;
}
codec47_comp1(ctx, dst, width, height, stride);
break;
case 2:
if (seq == ctx->prev_seq + 1) {