> +#define MODEL_MIN_SYMS 2
> +#define MODEL_MAX_SYMS 256
y u no align?
> +#define THRESH_ADAPTIVE -1
> +#define THRESH_LOW 15
> +#define THRESH_HIGH 50
> +#define THRESH_KOSTYA 1985
Will this be in the final push? I don't actually see
it being used anywhere. :P
> +static int arith_get_bit(ArithCoder *c)
> +{
> + int range = c->high - c->low + 1;
> + int bit = (((c->value - c->low) << 1) + 1) / range;
> +
> + if (bit)
> + c->low += range >> 1;
> + else
> + c->high = c->low + (range >> 1) - 1;
> +
> + arith_normalise(c);
> +
> + return bit;
> +}
> +
> +static int arith_get_bits(ArithCoder *c, int bits)
> +{
> + int range = c->high - c->low + 1;
> + int val = (((c->value - c->low + 1) << bits) - 1) / range;
> + int prob = range * val;
> +
> + c->high = ((prob + range) >> bits) + c->low - 1;
> + c->low += prob >> bits;
> +
> + arith_normalise(c);
> +
> + return val;
> +}
> +
> +static int arith_get_number(ArithCoder *c, int mod_val)
> +{
> + int range = c->high - c->low + 1;
> + int val = ((c->value - c->low + 1) * mod_val - 1) / range;
> + int prob = range * val;
> +
> + c->high = (prob + range) / mod_val + c->low - 1;
> + c->low += prob / mod_val;
> +
> + arith_normalise(c);
> +
> + return val;
> +}
> +
> +static int arith_get_prob(ArithCoder *c, int *probs)
> +{
> + int range = c->high - c->low + 1;
> + int val = ((c->value - c->low + 1) * probs[0] - 1) / range;
> + int sym = 1;
> +
> + while (probs[sym] > val)
> + sym++;
> +
> + c->high = range * probs[sym - 1] / probs[0] + c->low - 1;
> + c->low += range * probs[sym] / probs[0];
> +
> + return sym;
> +}
Is there any way to merge parts of these?
> +enum ContextDirection {
> + TOP_LEFT = 0,
> + TOP,
> + TOP_RIGHT,
> + LEFT
> +};
This should be moved to the top of the file, no?
> +static int decode_region(MSS1Context *ctx, ArithCoder *acoder, uint8_t *dst,
> + int x, int y, int width, int height, int stride,
> + PixContext *pctx)
> +{
> + int i, j;
> +
> + dst += x + y * stride;
> +
> + dst[0] = decode_top_left_pixel(acoder, pctx);
> + for (j = 0; j < height; j++) {
> + for (i = 0; i < width; i++) {
> + if (!i && !j)
> + continue;
> +
> + dst[i] = decode_pixel_in_context(acoder, pctx, dst + i, stride,
> + i, j, width - i - 1);
> + }
> + dst += stride;
> + }
> +
> + return 0;
> +}
> +
> +static int decode_region_masked(MSS1Context *ctx, ArithCoder *acoder,
> + uint8_t *dst, int stride, uint8_t *mask,
> + int mask_stride, int x, int y,
> + int width, int height,
> + PixContext *pctx)
> +{
> + int i, j;
> +
> + dst += x + y * stride;
> + mask += x + y * mask_stride;
> +
> + if (mask[0] != 0xFF)
> + dst[0] = decode_top_left_pixel(acoder, pctx);
> + for (j = 0; j < height; j++) {
> + for (i = 0; i < width; i++) {
> + if (!i && !j || mask[i] != 0xFF)
> + continue;
> +
> + dst[i] = decode_pixel_in_context(acoder, pctx, dst + i, stride,
> + i, j, width - i - 1);
> + }
> + dst += stride;
> + mask += mask_stride;
> + }
> +
> + return 0;
> +}
Possible merge?
> +AVCodec ff_mss1_decoder = {
> + .name = "mss1",
> + .type = AVMEDIA_TYPE_VIDEO,
> + .id = CODEC_ID_MSS1,
> + .priv_data_size = sizeof(MSS1Context),
> + .init = mss1_decode_init,
> + .close = mss1_decode_end,
> + .decode = mss1_decode_frame,
> + .capabilities = CODEC_CAP_DR1,
> + .long_name = NULL_IF_CONFIG_SMALL("MS Screen 1"),
> +};
I thought it was called MS Screen Codec 1? I'm probably misremembering.
Sorry for the lack of a real technical review.
- Derek
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