zimg: add support for 1 bit per pixel formats

Again worthless, slow, and only for libswscale parity.

With this, we support all formats libswscale supports, except bayer
input, and rgb4/bgr4 output. We even support some formats libswscale
doesn't.

It's possible that the zimg wrapper isn't always as fast as libswscale.
But there is optimization potential: the inner repack loops are
self-contained enough that they could be reasonably be implemented in
assembler (probably), and doing everything slice-wise should reduce the
overhead of the separate pack/unpack stages.

2 files changed, 54 insertions, 2 deletions

diff --git a/test/ref/zimg_formats.txt b/test/ref/zimg_formats.txt
index ef5b650a3f..26d260a70e 100644
--- a/test/ref/zimg_formats.txt
+++ b/test/ref/zimg_formats.txt
@@ -74,8 +74,8 @@
       grayf32be    Zin   Zout  SWSin  SWSout |
      mediacodec                              |
            mmal                              |
-          monob                SWSin  SWSout |
-          monow                SWSin  SWSout |
+          monob    Zin   Zout  SWSin  SWSout |
+          monow    Zin   Zout  SWSin  SWSout |
            nv12    Zin   Zout  SWSin  SWSout |
            nv16    Zin   Zout                |
            nv20    Zin   Zout                |
diff --git a/video/zimg.c b/video/zimg.c
index 951cf2c907..cd68495831 100644
--- a/video/zimg.c
+++ b/video/zimg.c
@@ -90,6 +90,8 @@ struct mp_zimg_repack {
     // Output bit depth. If 0, use format defaults. (Used by some packets. This
     // is simpler than defining fringe planar RGB formats for each depth.)
     int override_depth;
+    // Hammer it into using ZIMG_COLOR_GREY.
+    bool override_gray;
 
     // Endian-swap (done before/after actual repacker).
     int endian_size;            // 0=no swapping, 2/4=word byte size to swap
@@ -561,6 +563,40 @@ static int fringe_rgb_repack(void *user, unsigned i, unsigned x0, unsigned x1)
     return 0;
 }
 
+static int bitmap_repack(void *user, unsigned i, unsigned x0, unsigned x1)
+{
+    struct mp_zimg_repack *r = user;
+
+    // Supposedly zimg aligns this at least on 64 byte boundaries. Simplifies a
+    // lot for us.
+    assert(!(x0 & 7));
+
+    uint8_t *p1 =
+        r->mpi->planes[0] + r->mpi->stride[0] * (ptrdiff_t)(i - r->mpi_y0);
+    uint8_t *p2 =
+        r->tmp->planes[0] + r->tmp->stride[0] * (ptrdiff_t)(i & r->zmask[0]);
+
+    uint8_t swap = r->comp_size ? 0xFF : 0;
+    if (r->pack) {
+        for (int x = x0; x < x1; x += 8) {
+            uint8_t d = 0;
+            int max_b = MPMIN(8, x1 - x);
+            for (int b = 0; b < max_b; b++)
+                d |= (!!p2[x + b]) << (7 - b);
+            p1[x / 8] = d ^ swap;
+        }
+    } else {
+        for (int x = x0; x < x1; x += 8) {
+            uint8_t d = p1[x / 8] ^ swap;
+            int max_b = MPMIN(8, x1 - x);
+            for (int b = 0; b < max_b; b++)
+                p2[x + b] = !!(d & (1 << (7 - b)));
+        }
+    }
+
+    return 0;
+}
+
 static int unpack_pal(void *user, unsigned i, unsigned x0, unsigned x1)
 {
     struct mp_zimg_repack *r = user;
@@ -966,6 +1002,16 @@ static void setup_misc_packer(struct mp_zimg_repack *r)
             return;
         r->zimgfmt = grap_fmt;
         r->repack = unpack_pal;
+    } else {
+        enum AVPixelFormat avfmt = imgfmt2pixfmt(r->zimgfmt);
+        if (avfmt == AV_PIX_FMT_MONOWHITE || avfmt == AV_PIX_FMT_MONOBLACK) {
+            r->zimgfmt = IMGFMT_Y8;
+            r->repack = bitmap_repack;
+            r->override_depth = 1;
+            r->override_gray = true;
+            r->comp_size = avfmt == AV_PIX_FMT_MONOWHITE; // abuse to pass a flag
+            return;
+        }
     }
 }
 
@@ -1169,6 +1215,12 @@ static bool setup_format_ne(zimg_image_format *zfmt, struct mp_zimg_repack *r,
     zfmt->color_primaries = mp_to_z_prim(fmt.color.primaries);
     zfmt->chroma_location = mp_to_z_chroma(fmt.chroma_location);
 
+    if (r->override_gray) {
+        zfmt->color_family = ZIMG_COLOR_GREY;
+        zfmt->pixel_range = ZIMG_RANGE_FULL;
+        zfmt->matrix_coefficients = ZIMG_MATRIX_BT470_BG;
+    }
+
     if (ctx && ctx->opts.fast) {
         // mpv's default for RGB output slows down zimg significantly.
         if (zfmt->transfer_characteristics == ZIMG_TRANSFER_IEC_61966_2_1 &&