proresenc: alpha coding support

doc/encoders.texi

@@ -608,6 +608,7 @@ Select the ProRes profile to encode
 @item lt
 @item standard
 @item hq
+@item 4444
 @end table
 
 @item quant_mat @var{integer}
@@ -637,6 +638,11 @@ Override the 4-byte vendor ID.
 A custom vendor ID like @var{apl0} would claim the stream was produced by
 the Apple encoder.
 
+@item alpha_bits @var{integer}
+Specify number of bits for alpha component.
+Possible values are @var{0}, @var{8} and @var{16}.
+Use @var{0} to disable alpha plane coding.
+
 @end table
 
 @subsection Speed considerations

libavcodec/proresenc.c

@@ -21,6 +21,7 @@
  */
 
 #include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
 #include "avcodec.h"
 #include "dsputil.h"
 #include "put_bits.h"
@@ -34,13 +35,14 @@
 
 #define MAX_MBS_PER_SLICE 8
 
-#define MAX_PLANES 3 // should be increased to 4 when there's AV_PIX_FMT_YUV444AP10
+#define MAX_PLANES 4
 
 enum {
     PRORES_PROFILE_PROXY = 0,
     PRORES_PROFILE_LT,
     PRORES_PROFILE_STANDARD,
     PRORES_PROFILE_HQ,
+    PRORES_PROFILE_4444,
 };
 
 enum {
@@ -119,7 +121,7 @@ static const struct prores_profile {
     int         max_quant;
     int         br_tab[NUM_MB_LIMITS];
     int         quant;
-} prores_profile_info[4] = {
+} prores_profile_info[5] = {
     {
         .full_name = "proxy",
         .tag       = MKTAG('a', 'p', 'c', 'o'),
@@ -151,8 +153,15 @@ static const struct prores_profile {
         .max_quant = 6,
         .br_tab    = { 1566, 1216, 1070, 950 },
         .quant     = QUANT_MAT_HQ,
+    },
+    {
+        .full_name = "4444",
+        .tag       = MKTAG('a', 'p', '4', 'h'),
+        .min_quant = 1,
+        .max_quant = 6,
+        .br_tab    = { 2350, 1828, 1600, 1425 },
+        .quant     = QUANT_MAT_HQ,
     }
-// for 4444 profile bitrate numbers are { 2350, 1828, 1600, 1425 }
 };
 
 #define TRELLIS_WIDTH 16
@@ -195,6 +204,7 @@ typedef struct ProresContext {
     int num_planes;
     int bits_per_mb;
     int force_quant;
+    int alpha_bits;
 
     char *vendor;
     int quant_sel;
@@ -280,6 +290,34 @@ static void get_slice_data(ProresContext *ctx, const uint16_t *src,
     }
 }
 
+static void get_alpha_data(ProresContext *ctx, const uint16_t *src,
+                           int linesize, int x, int y, int w, int h,
+                           int16_t *blocks, int mbs_per_slice, int abits)
+{
+    const int slice_width = 16 * mbs_per_slice;
+    int i, j, copy_w, copy_h;
+
+    copy_w = FFMIN(w - x, slice_width);
+    copy_h = FFMIN(h - y, 16);
+    for (i = 0; i < copy_h; i++) {
+        memcpy(blocks, src, copy_w * sizeof(*src));
+        if (abits == 8)
+            for (j = 0; j < copy_w; j++)
+                blocks[j] >>= 2;
+        else
+            for (j = 0; j < copy_w; j++)
+                blocks[j] = (blocks[j] << 6) | (blocks[j] >> 4);
+        for (j = copy_w; j < slice_width; j++)
+            blocks[j] = blocks[copy_w - 1];
+        blocks += slice_width;
+        src    += linesize >> 1;
+    }
+    for (; i < 16; i++) {
+        memcpy(blocks, blocks - slice_width, slice_width * sizeof(*blocks));
+        blocks += slice_width;
+    }
+}
+
 /**
  * Write an unsigned rice/exp golomb codeword.
  */
@@ -394,6 +432,73 @@ static int encode_slice_plane(ProresContext *ctx, PutBitContext *pb,
     return (put_bits_count(pb) - saved_pos) >> 3;
 }
 
+static void put_alpha_diff(PutBitContext *pb, int cur, int prev, int abits)
+{
+    const int mask  = (1 << abits) - 1;
+    const int dbits = (abits == 8) ? 4 : 7;
+    const int dsize = 1 << dbits - 1;
+    int diff = cur - prev;
+
+    diff &= mask;
+    if (diff >= (1 << abits) - dsize)
+        diff -= 1 << abits;
+    if (diff < -dsize || diff > dsize || !diff) {
+        put_bits(pb, 1, 1);
+        put_bits(pb, abits, diff);
+    } else {
+        put_bits(pb, 1, 0);
+        put_bits(pb, dbits - 1, FFABS(diff) - 1);
+        put_bits(pb, 1, diff < 0);
+    }
+}
+
+static void put_alpha_run(PutBitContext *pb, int run)
+{
+    if (run) {
+        put_bits(pb, 1, 0);
+        if (run < 0x10)
+            put_bits(pb, 4, run);
+        else
+            put_bits(pb, 15, run);
+    } else {
+        put_bits(pb, 1, 1);
+    }
+}
+
+// todo alpha quantisation for high quants
+static int encode_alpha_plane(ProresContext *ctx, PutBitContext *pb,
+                              const uint16_t *src, int linesize,
+                              int mbs_per_slice, uint16_t *blocks,
+                              int quant)
+{
+    const int abits = ctx->alpha_bits;
+    const int mask  = (1 << abits) - 1;
+    const int num_coeffs = mbs_per_slice * 256;
+    int saved_pos = put_bits_count(pb);
+    int prev = mask, cur;
+    int idx = 0;
+    int run = 0;
+
+    cur = blocks[idx++];
+    put_alpha_diff(pb, cur, prev, abits);
+    prev = cur;
+    do {
+        cur = blocks[idx++];
+        if (cur != prev) {
+            put_alpha_run (pb, run);
+            put_alpha_diff(pb, cur, prev, abits);
+            prev = cur;
+            run  = 0;
+        } else {
+            run++;
+        }
+    } while (idx < num_coeffs);
+    if (run)
+        put_alpha_run(pb, run);
+    flush_put_bits(pb);
+    return (put_bits_count(pb) - saved_pos) >> 3;
+}
+
 static int encode_slice(AVCodecContext *avctx, const AVFrame *pic,
                         PutBitContext *pb,
                         int sizes[4], int x, int y, int quant,
@@ -444,14 +549,23 @@ static int encode_slice(AVCodecContext *avctx, const AVFrame *pic,
         src = (const uint16_t*)(pic->data[i] + yp * linesize +
                                 line_add * pic->linesize[i]) + xp;
 
-        get_slice_data(ctx, src, linesize, xp, yp,
-                       pwidth, avctx->height / ctx->pictures_per_frame,
-                       ctx->blocks[0], ctx->emu_buf,
-                       mbs_per_slice, num_cblocks, is_chroma);
-        sizes[i] = encode_slice_plane(ctx, pb, src, linesize,
-                                      mbs_per_slice, ctx->blocks[0],
-                                      num_cblocks, plane_factor,
-                                      qmat);
+        if (i < 3) {
+            get_slice_data(ctx, src, linesize, xp, yp,
+                           pwidth, avctx->height / ctx->pictures_per_frame,
+                           ctx->blocks[0], ctx->emu_buf,
+                           mbs_per_slice, num_cblocks, is_chroma);
+            sizes[i] = encode_slice_plane(ctx, pb, src, linesize,
+                                          mbs_per_slice, ctx->blocks[0],
+                                          num_cblocks, plane_factor,
+                                          qmat);
+        } else {
+            get_alpha_data(ctx, src, linesize, xp, yp,
+                           pwidth, avctx->height / ctx->pictures_per_frame,
+                           ctx->blocks[0], mbs_per_slice, ctx->alpha_bits);
+            sizes[i] = encode_alpha_plane(ctx, pb, src, linesize,
+                                          mbs_per_slice, ctx->blocks[0],
+                                          quant);
+        }
         total_size += sizes[i];
     }
     return total_size;
@@ -564,6 +678,66 @@ static int estimate_slice_plane(ProresContext *ctx, int *error, int plane,
     return FFALIGN(bits, 8);
 }
 
+static int est_alpha_diff(int cur, int prev, int abits)
+{
+    const int mask  = (1 << abits) - 1;
+    const int dbits = (abits == 8) ? 4 : 7;
+    const int dsize = 1 << dbits - 1;
+    int diff = cur - prev;
+
+    diff &= mask;
+    if (diff >= (1 << abits) - dsize)
+        diff -= 1 << abits;
+    if (diff < -dsize || diff > dsize || !diff)
+        return abits + 1;
+    else
+        return dbits + 1;
+}
+
+static int estimate_alpha_plane(ProresContext *ctx, int *error,
+                                const uint16_t *src, int linesize,
+                                int mbs_per_slice, int quant,
+                                int16_t *blocks)
+{
+    const int abits = ctx->alpha_bits;
+    const int mask  = (1 << abits) - 1;
+    const int num_coeffs = mbs_per_slice * 256;
+    int prev = mask, cur;
+    int idx = 0;
+    int run = 0;
+    int bits;
+
+    *error = 0;
+    cur = blocks[idx++];
+    bits = est_alpha_diff(cur, prev, abits);
+    prev = cur;
+    do {
+        cur = blocks[idx++];
+        if (cur != prev) {
+            if (!run)
+                bits++;
+            else if (run < 0x10)
+                bits += 4;
+            else
+                bits += 15;
+            bits += est_alpha_diff(cur, prev, abits);
+            prev = cur;
+            run  = 0;
+        } else {
+            run++;
+        }
+    } while (idx < num_coeffs);
+
+    if (run) {
+        if (run < 0x10)
+            bits += 4;
+        else
+            bits += 15;
+    }
+
+    return bits;
+}
+
 static int find_slice_quant(AVCodecContext *avctx, const AVFrame *pic,
                             int trellis_node, int x, int y, int mbs_per_slice,
                             ProresThreadData *td)
@@ -610,10 +784,16 @@ static int find_slice_quant(AVCodecContext *avctx, const AVFrame *pic,
         src = (const uint16_t*)(pic->data[i] + yp * linesize[i] +
                                 line_add * pic->linesize[i]) + xp;
 
-        get_slice_data(ctx, src, linesize[i], xp, yp,
-                       pwidth, avctx->height / ctx->pictures_per_frame,
-                       td->blocks[i], td->emu_buf,
-                       mbs_per_slice, num_cblocks[i], is_chroma[i]);
+        if (i < 3) {
+            get_slice_data(ctx, src, linesize[i], xp, yp,
+                           pwidth, avctx->height / ctx->pictures_per_frame,
+                           td->blocks[i], td->emu_buf,
+                           mbs_per_slice, num_cblocks[i], is_chroma[i]);
+        } else {
+            get_alpha_data(ctx, src, linesize[i], xp, yp,
+                           pwidth, avctx->height / ctx->pictures_per_frame,
+                           td->blocks[i], mbs_per_slice, ctx->alpha_bits);
+        }
     }
 
     for (q = min_quant; q < max_quant + 2; q++) {
@@ -625,13 +805,16 @@ static int find_slice_quant(AVCodecContext *avctx, const AVFrame *pic,
     for (q = min_quant; q <= max_quant; q++) {
         bits  = 0;
         error = 0;
-        for (i = 0; i < ctx->num_planes; i++) {
+        for (i = 0; i < ctx->num_planes - !!ctx->alpha_bits; i++) {
             bits += estimate_slice_plane(ctx, &error, i,
                                          src, linesize[i],
                                          mbs_per_slice,
                                          num_cblocks[i], plane_factor[i],
                                          ctx->quants[q], td);
         }
+        if (ctx->alpha_bits)
+            bits += estimate_alpha_plane(ctx, &error, src, linesize[3],
+                                         mbs_per_slice, q, td->blocks[3]);
         if (bits > 65000 * 8) {
             error = SCORE_LIMIT;
             break;
@@ -654,13 +837,16 @@ static int find_slice_quant(AVCodecContext *avctx, const AVFrame *pic,
                 for (i = 0; i < 64; i++)
                     qmat[i] = ctx->quant_mat[i] * q;
             }
-            for (i = 0; i < ctx->num_planes; i++) {
+            for (i = 0; i < ctx->num_planes - !!ctx->alpha_bits; i++) {
                 bits += estimate_slice_plane(ctx, &error, i,
                                              src, linesize[i],
                                              mbs_per_slice,
                                              num_cblocks[i], plane_factor[i],
                                              qmat, td);
             }
+            if (ctx->alpha_bits)
+                bits += estimate_alpha_plane(ctx, &error, src, linesize[3],
+                                             mbs_per_slice, q, td->blocks[3]);
             if (bits <= ctx->bits_per_mb * mbs_per_slice)
                 break;
         }
@@ -782,7 +968,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     bytestream_put_byte  (&buf, avctx->color_primaries);
     bytestream_put_byte  (&buf, avctx->color_trc);
     bytestream_put_byte  (&buf, avctx->colorspace);
-    bytestream_put_byte  (&buf, 0x40);          // source format and alpha information
+    bytestream_put_byte  (&buf, 0x40 | (ctx->alpha_bits >> 3));
     bytestream_put_byte  (&buf, 0);             // reserved
     if (ctx->quant_sel != QUANT_MAT_DEFAULT) {
         bytestream_put_byte  (&buf, 0x03);      // matrix flags - both matrices are present
@@ -904,12 +1090,20 @@ static av_cold int encode_init(AVCodecContext *avctx)
                "there should be an integer power of two MBs per slice\n");
         return AVERROR(EINVAL);
     }
+    if (av_pix_fmt_desc_get(avctx->pix_fmt)->flags & AV_PIX_FMT_FLAG_ALPHA) {
+        if (ctx->alpha_bits & 7) {
+            av_log(avctx, AV_LOG_ERROR, "alpha bits should be 0, 8 or 16\n");
+            return AVERROR(EINVAL);
+        }
+    } else {
+        ctx->alpha_bits = 0;
+    }
 
     ctx->chroma_factor = avctx->pix_fmt == AV_PIX_FMT_YUV422P10
                          ? CFACTOR_Y422
                          : CFACTOR_Y444;
     ctx->profile_info  = prores_profile_info + ctx->profile;
-    ctx->num_planes    = 3;
+    ctx->num_planes    = 3 + !!ctx->alpha_bits;
 
     ctx->mb_width      = FFALIGN(avctx->width,  16) >> 4;
 
@@ -1025,7 +1219,7 @@ static const AVOption options[] = {
         AV_OPT_TYPE_INT, { .i64 = 8 }, 1, MAX_MBS_PER_SLICE, VE },
     { "profile",       NULL, OFFSET(profile), AV_OPT_TYPE_INT,
         { .i64 = PRORES_PROFILE_STANDARD },
-        PRORES_PROFILE_PROXY, PRORES_PROFILE_HQ, VE, "profile" },
+        PRORES_PROFILE_PROXY, PRORES_PROFILE_4444, VE, "profile" },
     { "proxy",         NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PRORES_PROFILE_PROXY },
         0, 0, VE, "profile" },
     { "lt",            NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PRORES_PROFILE_LT },
@@ -1034,6 +1228,8 @@ static const AVOption options[] = {
         0, 0, VE, "profile" },
     { "hq",            NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PRORES_PROFILE_HQ },
         0, 0, VE, "profile" },
+    { "4444",          NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PRORES_PROFILE_4444 },
+        0, 0, VE, "profile" },
     { "vendor", "vendor ID", OFFSET(vendor),
         AV_OPT_TYPE_STRING, { .str = "Lavc" }, CHAR_MIN, CHAR_MAX, VE },
     { "bits_per_mb", "desired bits per macroblock", OFFSET(bits_per_mb),
@@ -1052,6 +1248,8 @@ static const AVOption options[] = {
         0, 0, VE, "quant_mat" },
     { "default",       NULL, 0, AV_OPT_TYPE_CONST, { .i64 = QUANT_MAT_DEFAULT },
         0, 0, VE, "quant_mat" },
+    { "alpha_bits", "bits for alpha plane", OFFSET(alpha_bits), AV_OPT_TYPE_INT,
+        { .i64 = 16 }, 0, 16, VE },
     { NULL }
 };
 
@@ -1073,7 +1271,8 @@ AVCodec ff_prores_encoder = {
     .capabilities   = CODEC_CAP_SLICE_THREADS,
     .long_name      = NULL_IF_CONFIG_SMALL("Apple ProRes (iCodec Pro)"),
     .pix_fmts       = (const enum AVPixelFormat[]) {
-                          AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV444P10, AV_PIX_FMT_NONE
+                          AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV444P10,
+                          AV_PIX_FMT_YUVA444P10, AV_PIX_FMT_NONE
                       },
     .priv_class     = &proresenc_class,
 };