lavc: add xface image decoder and encoder

Based on libcompface code by James Ashton <James.Ashton@anu.edu.au>, and
relicensed to LGPL with the author's consent.

Changelog

@@ -11,6 +11,7 @@ version next:
 - TAK demuxer, decoder and parser
 - DTS-HD demuxer
 - remove -same_quant, it hasn't worked for years
+- X-Face image encoder and decoder
 
 
 version 1.0:

doc/general.texi

@@ -441,6 +441,8 @@ following image formats are supported:
     @tab Targa (.TGA) image format
 @item XBM  @tab X @tab X
     @tab X BitMap image format
+@item XFace @tab X @tab X
+    @tab X-Face image format
 @item XWD  @tab X @tab X
     @tab X Window Dump image format
 @end multitable

libavcodec/Makefile

@@ -482,6 +482,8 @@ OBJS-$(CONFIG_XAN_WC4_DECODER)         += xxan.o
 OBJS-$(CONFIG_XBIN_DECODER)            += bintext.o cga_data.o
 OBJS-$(CONFIG_XBM_DECODER)             += xbmdec.o
 OBJS-$(CONFIG_XBM_ENCODER)             += xbmenc.o
+OBJS-$(CONFIG_XFACE_DECODER)           += xfacedec.o xface.o
+OBJS-$(CONFIG_XFACE_ENCODER)           += xfaceenc.o xface.o
 OBJS-$(CONFIG_XL_DECODER)              += xl.o
 OBJS-$(CONFIG_XSUB_DECODER)            += xsubdec.o
 OBJS-$(CONFIG_XSUB_ENCODER)            += xsubenc.o

libavcodec/allcodecs.c

@@ -265,6 +265,7 @@ void avcodec_register_all(void)
     REGISTER_DECODER (XAN_WC3, xan_wc3);
     REGISTER_DECODER (XAN_WC4, xan_wc4);
     REGISTER_ENCDEC  (XBM, xbm);
+    REGISTER_ENCDEC  (XFACE, xface);
     REGISTER_DECODER (XL, xl);
     REGISTER_ENCDEC  (XWD, xwd);
     REGISTER_ENCDEC  (Y41P, y41p);

libavcodec/avcodec.h

@@ -283,6 +283,7 @@ enum AVCodecID {
     AV_CODEC_ID_PAF_VIDEO  = MKBETAG('P','A','F','V'),
     AV_CODEC_ID_AVRN       = MKBETAG('A','V','R','n'),
     AV_CODEC_ID_CPIA       = MKBETAG('C','P','I','A'),
+    AV_CODEC_ID_XFACE      = MKBETAG('X','F','A','C'),
 
     /* various PCM "codecs" */
     AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs

libavcodec/codec_desc.c

@@ -1315,6 +1315,12 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .name      = "cpia",
         .long_name = NULL_IF_CONFIG_SMALL("CPiA video format"),
     },
+    {
+        .id        = AV_CODEC_ID_XFACE,
+        .type      = AVMEDIA_TYPE_VIDEO,
+        .name      = "xface",
+        .long_name = NULL_IF_CONFIG_SMALL("X-face image"),
+    },
 
     /* various PCM "codecs" */
     {

libavcodec/version.h

@@ -29,7 +29,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVCODEC_VERSION_MAJOR 54
-#define LIBAVCODEC_VERSION_MINOR 65
+#define LIBAVCODEC_VERSION_MINOR 66
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \

libavcodec/xface.c

@@ -0,0 +1,381 @@
+/*
+ * Copyright (c) 1990 James Ashton - Sydney University
+ * Copyright (c) 2012 Stefano Sabatini
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * X-Face common data and utilities definition.
+ */
+
+#include "xface.h"
+
+void ff_big_add(BigInt *b, uint8_t a)
+{
+    int i;
+    uint8_t *w;
+    uint16_t c;
+
+    a &= XFACE_WORDMASK;
+    if (a == 0)
+        return;
+    w = b->words;
+    c = a;
+    for (i = 0; i < b->nb_words && c; i++) {
+        c += *w;
+        *w++ = c & XFACE_WORDMASK;
+        c >>= XFACE_BITSPERWORD;
+    }
+    if (i == b->nb_words && c) {
+        b->nb_words++;
+        *w = c & XFACE_WORDMASK;
+    }
+}
+
+void ff_big_div(BigInt *b, uint8_t a, uint8_t *r)
+{
+    int i;
+    uint8_t *w;
+    uint16_t c, d;
+
+    a &= XFACE_WORDMASK;
+    if (a == 1 || b->nb_words == 0) {
+        *r = 0;
+        return;
+    }
+
+    /* treat this as a == WORDCARRY and just shift everything right a WORD */
+    if (a == 0) {
+        i = --b->nb_words;
+        w = b->words;
+        *r = *w;
+        while (i--) {
+            *w = *(w + 1);
+            w++;
+        }
+        *w = 0;
+        return;
+    }
+    i = b->nb_words;
+    w = b->words + i;
+    c = 0;
+    while (i--) {
+        c <<= XFACE_BITSPERWORD;
+        c += *--w;
+        d = c / (uint16_t)a;
+        c = c % (uint16_t)a;
+        *w = d & XFACE_WORDMASK;
+    }
+    *r = c;
+    if (b->words[b->nb_words - 1] == 0)
+        b->nb_words--;
+}
+
+void ff_big_mul(BigInt *b, uint8_t a)
+{
+    int i;
+    uint8_t *w;
+    uint16_t c;
+
+    a &= XFACE_WORDMASK;
+    if (a == 1 || b->nb_words == 0)
+        return;
+    if (a == 0) {
+        /* treat this as a == WORDCARRY and just shift everything left a WORD */
+        i = b->nb_words++;
+        w = b->words + i;
+        while (i--) {
+            *w = *(w - 1);
+            w--;
+        }
+        *w = 0;
+        return;
+    }
+    i = b->nb_words;
+    w = b->words;
+    c = 0;
+    while (i--) {
+        c += (uint16_t)*w * (uint16_t)a;
+        *(w++) = c & XFACE_WORDMASK;
+        c >>= XFACE_BITSPERWORD;
+    }
+    if (c) {
+        b->nb_words++;
+        *w = c & XFACE_WORDMASK;
+    }
+}
+
+const ProbRange ff_xface_probranges_per_level[4][3] = {
+    //  black      grey       white
+    { {  1, 255}, {251, 0}, {  4, 251} }, /* Top of tree almost always grey */
+    { {  1, 255}, {200, 0}, { 55, 200} },
+    { { 33, 223}, {159, 0}, { 64, 159} },
+    { {131,   0}, {  0, 0}, {125, 131} }, /* Grey disallowed at bottom */
+};
+
+const ProbRange ff_xface_probranges_2x2[16] = {
+    { 0,   0},  {38,   0}, {38,  38},  {13, 152},
+    {38,  76},  {13, 165}, {13, 178},  { 6, 230},
+    {38, 114},  {13, 191}, {13, 204},  { 6, 236},
+    {13, 217},  { 6, 242}, { 5, 248},  { 3, 253},
+};
+
+/*
+ * The "guess the next pixel" tables follow. Normally there are 12
+ * neighbour pixels used to give 1<<12 cases as we get closer to the
+ * upper left corner lesser numbers of neighbours are available.
+ *
+ * Each byte in the tables represents 8 boolean values starting from
+ * the most significant bit.
+ */
+
+static const uint8_t g_00[] = {
+    0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0xe3, 0xdf, 0x05, 0x17,
+    0x05, 0x0f, 0x00, 0x1b, 0x0f, 0xdf, 0x00, 0x04, 0x00, 0x00,
+    0x0d, 0x0f, 0x03, 0x7f, 0x00, 0x00, 0x00, 0x01, 0x00, 0x1d,
+    0x45, 0x2f, 0x00, 0x00, 0x00, 0x0d, 0x00, 0x0a, 0xff, 0xff,
+    0x00, 0x04, 0x00, 0x05, 0x01, 0x3f, 0xcf, 0xff, 0x10, 0x01,
+    0x80, 0xc9, 0x0f, 0x0f, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
+    0x1b, 0x1f, 0xff, 0xff, 0x4f, 0x54, 0x07, 0x1f, 0x57, 0x47,
+    0xd7, 0x3d, 0xff, 0xff, 0x5f, 0x1f, 0x7f, 0xff, 0x7f, 0x7f,
+    0x05, 0x0f, 0x01, 0x0f, 0x0f, 0x5f, 0x9b, 0xdf, 0x7f, 0xff,
+    0x5f, 0x1d, 0x5f, 0xff, 0x0f, 0x1f, 0x0f, 0x5f, 0x03, 0x1f,
+    0x4f, 0x5f, 0xf7, 0x7f, 0x7f, 0xff, 0x0d, 0x0f, 0xfb, 0xff,
+    0xf7, 0xbf, 0x0f, 0x4f, 0xd7, 0x3f, 0x4f, 0x7f, 0xff, 0xff,
+    0x67, 0xbf, 0x56, 0x25, 0x1f, 0x7f, 0x9f, 0xff, 0x00, 0x00,
+    0x00, 0x05, 0x5f, 0x7f, 0x01, 0xdf, 0x14, 0x00, 0x05, 0x0f,
+    0x07, 0xa2, 0x09, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x5f,
+    0x18, 0xd7, 0x94, 0x71, 0x00, 0x05, 0x1f, 0xb7, 0x0c, 0x07,
+    0x0f, 0x0f, 0x00, 0x0f, 0x0f, 0x1f, 0x84, 0x8f, 0x05, 0x15,
+    0x05, 0x0f, 0x4f, 0xff, 0x87, 0xdf, 0x05, 0x01, 0x10, 0x00,
+    0x0f, 0x0f, 0x00, 0x08, 0x05, 0x04, 0x04, 0x01, 0x4f, 0xff,
+    0x9f, 0x8f, 0x4a, 0x40, 0x5f, 0x5f, 0xff, 0xfe, 0xdf, 0xff,
+    0x7f, 0xf7, 0xff, 0x7f, 0xff, 0xff, 0x7b, 0xff, 0x0f, 0xfd,
+    0xd7, 0x5f, 0x4f, 0x7f, 0x7f, 0xdf, 0xff, 0xff, 0xff, 0xff,
+    0xff, 0x77, 0xdf, 0x7f, 0x4f, 0xef, 0xff, 0xff, 0x77, 0xff,
+    0xff, 0xff, 0x6f, 0xff, 0x0f, 0x4f, 0xff, 0xff, 0x9d, 0xff,
+    0x0f, 0xef, 0xff, 0xdf, 0x6f, 0xff, 0xff, 0xff, 0x4f, 0xff,
+    0xcd, 0x0f, 0x4f, 0xff, 0xff, 0xdf, 0x00, 0x00, 0x00, 0x0b,
+    0x05, 0x02, 0x02, 0x0f, 0x04, 0x00, 0x00, 0x0c, 0x01, 0x06,
+    0x00, 0x0f, 0x20, 0x03, 0x00, 0x00, 0x05, 0x0f, 0x40, 0x08,
+    0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x0c, 0x0f, 0x01, 0x00,
+    0x80, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x14, 0x01, 0x05,
+    0x01, 0x15, 0xaf, 0x0f, 0x00, 0x01, 0x10, 0x00, 0x08, 0x00,
+    0x46, 0x0c, 0x20, 0x00, 0x88, 0x00, 0x0f, 0x15, 0xff, 0xdf,
+    0x02, 0x00, 0x00, 0x0f, 0x7f, 0x5f, 0xdb, 0xff, 0x4f, 0x3e,
+    0x05, 0x0f, 0x7f, 0xf7, 0x95, 0x4f, 0x0d, 0x0f, 0x01, 0x0f,
+    0x4f, 0x5f, 0x9f, 0xdf, 0x25, 0x0e, 0x0d, 0x0d, 0x4f, 0x7f,
+    0x8f, 0x0f, 0x0f, 0xfa, 0x04, 0x4f, 0x4f, 0xff, 0xf7, 0x77,
+    0x47, 0xed, 0x05, 0x0f, 0xff, 0xff, 0xdf, 0xff, 0x4f, 0x6f,
+    0xd8, 0x5f, 0x0f, 0x7f, 0xdf, 0x5f, 0x07, 0x0f, 0x94, 0x0d,
+    0x1f, 0xff, 0xff, 0xff, 0x00, 0x02, 0x00, 0x03, 0x46, 0x57,
+    0x01, 0x0d, 0x01, 0x08, 0x01, 0x0f, 0x47, 0x6c, 0x0d, 0x0f,
+    0x02, 0x00, 0x00, 0x00, 0x0b, 0x4f, 0x00, 0x08, 0x05, 0x00,
+    0x95, 0x01, 0x0f, 0x7f, 0x0c, 0x0f, 0x01, 0x0e, 0x00, 0x00,
+    0x0f, 0x41, 0x00, 0x00, 0x04, 0x24, 0x0d, 0x0f, 0x0f, 0x7f,
+    0xcf, 0xdf, 0x00, 0x00, 0x00, 0x00, 0x04, 0x40, 0x00, 0x00,
+    0x06, 0x26, 0xcf, 0x05, 0xcf, 0x7f, 0xdf, 0xdf, 0x00, 0x00,
+    0x17, 0x5f, 0xff, 0xfd, 0xff, 0xff, 0x46, 0x09, 0x4f, 0x5f,
+    0x7f, 0xfd, 0xdf, 0xff, 0x0a, 0x88, 0xa7, 0x7f, 0x7f, 0xff,
+    0xff, 0xff, 0x0f, 0x04, 0xdf, 0x7f, 0x4f, 0xff, 0x9f, 0xff,
+    0x0e, 0xe6, 0xdf, 0xff, 0x7f, 0xff, 0xff, 0xff, 0x0f, 0xec,
+    0x8f, 0x4f, 0x7f, 0xff, 0xdf, 0xff, 0x0f, 0xcf, 0xdf, 0xff,
+    0x6f, 0x7f, 0xff, 0xff, 0x03, 0x0c, 0x9d, 0x0f, 0x7f, 0xff,
+    0xff, 0xff,
+};
+
+static const uint8_t g_01[] = {
+    0x37, 0x73, 0x00, 0x19, 0x57, 0x7f, 0xf5, 0xfb, 0x70, 0x33,
+    0xf0, 0xf9, 0x7f, 0xff, 0xff, 0xff,
+};
+
+static const uint8_t g_02[] = {
+    0x50,
+};
+
+static const uint8_t g_10[] = {
+    0x00, 0x00, 0x00, 0x00, 0x50, 0x00, 0xf3, 0x5f, 0x84, 0x04,
+    0x17, 0x9f, 0x04, 0x23, 0x05, 0xff, 0x00, 0x00, 0x00, 0x02,
+    0x03, 0x03, 0x33, 0xd7, 0x05, 0x03, 0x5f, 0x3f, 0x17, 0x33,
+    0xff, 0xff, 0x00, 0x80, 0x02, 0x04, 0x12, 0x00, 0x11, 0x57,
+    0x05, 0x25, 0x05, 0x03, 0x35, 0xbf, 0x9f, 0xff, 0x07, 0x6f,
+    0x20, 0x40, 0x17, 0x06, 0xfa, 0xe8, 0x01, 0x07, 0x1f, 0x9f,
+    0x1f, 0xff, 0xff, 0xff,
+};
+
+static const uint8_t g_20[] = {
+    0x04, 0x00, 0x01, 0x01, 0x43, 0x2e, 0xff, 0x3f,
+};
+
+static const uint8_t g_30[] = {
+    0x11, 0x11, 0x11, 0x11, 0x51, 0x11, 0x13, 0x11, 0x11, 0x11,
+    0x13, 0x11, 0x11, 0x11, 0x33, 0x11, 0x13, 0x11, 0x13, 0x13,
+    0x13, 0x13, 0x31, 0x31, 0x11, 0x01, 0x11, 0x11, 0x71, 0x11,
+    0x11, 0x75,
+};
+
+static const uint8_t g_40[] = {
+    0x00, 0x0f, 0x00, 0x09, 0x00, 0x0d, 0x00, 0x0d, 0x00, 0x0f,
+    0x00, 0x4e, 0xe4, 0x0d, 0x10, 0x0f, 0x00, 0x0f, 0x44, 0x4f,
+    0x00, 0x1e, 0x0f, 0x0f, 0xae, 0xaf, 0x45, 0x7f, 0xef, 0xff,
+    0x0f, 0xff, 0x00, 0x09, 0x01, 0x11, 0x00, 0x01, 0x1c, 0xdd,
+    0x00, 0x15, 0x00, 0xff, 0x00, 0x10, 0x00, 0xfd, 0x00, 0x0f,
+    0x4f, 0x5f, 0x3d, 0xff, 0xff, 0xff, 0x4f, 0xff, 0x1c, 0xff,
+    0xdf, 0xff, 0x8f, 0xff, 0x00, 0x0d, 0x00, 0x00, 0x00, 0x15,
+    0x01, 0x07, 0x00, 0x01, 0x02, 0x1f, 0x01, 0x11, 0x05, 0x7f,
+    0x00, 0x1f, 0x41, 0x57, 0x1f, 0xff, 0x05, 0x77, 0x0d, 0x5f,
+    0x4d, 0xff, 0x4f, 0xff, 0x0f, 0xff, 0x00, 0x00, 0x02, 0x05,
+    0x00, 0x11, 0x05, 0x7d, 0x10, 0x15, 0x2f, 0xff, 0x40, 0x50,
+    0x0d, 0xfd, 0x04, 0x0f, 0x07, 0x1f, 0x07, 0x7f, 0x0f, 0xbf,
+    0x0d, 0x7f, 0x0f, 0xff, 0x4d, 0x7d, 0x0f, 0xff,
+};
+
+static const uint8_t g_11[] = {
+    0x01, 0x13, 0x03, 0x7f,
+};
+
+static const uint8_t g_21[] = {
+    0x17,
+};
+
+static const uint8_t g_31[] = {
+    0x55, 0x57, 0x57, 0x7f,
+};
+
+static const uint8_t g_41[] = {
+    0x01, 0x01, 0x01, 0x1f, 0x03, 0x1f, 0x3f, 0xff,
+};
+
+static const uint8_t g_12[] = {
+    0x40,
+};
+
+static const uint8_t g_22[] = {
+    0x00,
+};
+
+static const uint8_t g_32[] = {
+    0x10,
+};
+
+static const uint8_t g_42[] = {
+    0x10,
+};
+
+void ff_xface_generate_face(uint8_t *dst, uint8_t * const src)
+{
+    int h, i, j, k, l, m;
+
+    for (j = 0; j < XFACE_HEIGHT; j++) {
+        for (i = 0; i < XFACE_WIDTH; i++) {
+            h = i + j * XFACE_WIDTH;
+            k = 0;
+
+            /*
+               Compute k, encoding the bits *before* the current one, contained in the
+               image buffer. That is, given the grid:
+
+                l      i
+                |      |
+                v      v
+               +--+--+--+--+--+
+          m -> | 1| 2| 3| 4| 5|
+               +--+--+--+--+--+
+               | 6| 7| 8| 9|10|
+               +--+--+--+--+--+
+          j -> |11|12| *|  |  |
+               +--+--+--+--+--+
+
+               the value k for the pixel marked as "*" will contain the bit encoding of
+               the values in the matrix marked from "1" to "12". In case the pixel is
+               near the border of the grid, the number of values contained within the
+               grid will be lesser than 12.
+             */
+
+            for (l = i - 2; l <= i + 2; l++) {
+                for (m = j - 2; m <= j; m++) {
+                    if (l >= i && m == j)
+                        continue;
+                    if (l > 0 && l <= XFACE_WIDTH && m > 0)
+                        k = 2*k + src[l + m * XFACE_WIDTH];
+                }
+            }
+
+            /*
+              Use the guess for the given position and the computed value of k.
+
+              The following table shows the number of digits in k, depending on
+              the position of the pixel, and shows the corresponding guess table
+              to use:
+
+                 i=1  i=2  i=3       i=w-1 i=w
+               +----+----+----+ ... +----+----+
+           j=1 |  0 |  1 |  2 |     |  2 |  2 |
+               |g22 |g12 |g02 |     |g42 |g32 |
+               +----+----+----+ ... +----+----+
+           j=2 |  3 |  5 |  7 |     |  6 |  5 |
+               |g21 |g11 |g01 |     |g41 |g31 |
+               +----+----+----+ ... +----+----+
+           j=3 |  5 |  9 | 12 |     | 10 |  8 |
+               |g20 |g10 |g00 |     |g40 |g30 |
+               +----+----+----+ ... +----+----+
+            */
+
+#define GEN(table) dst[h] ^= (table[k>>3]>>(7-(k&7)))&1
+
+            switch (i) {
+            case 1:
+                switch (j) {
+                case 1:  GEN(g_22); break;
+                case 2:  GEN(g_21); break;
+                default: GEN(g_20); break;
+                }
+                break;
+            case 2:
+                switch (j) {
+                case 1:  GEN(g_12); break;
+                case 2:  GEN(g_11); break;
+                default: GEN(g_10); break;
+                }
+                break;
+            case XFACE_WIDTH - 1:
+                switch (j) {
+                case 1:  GEN(g_42); break;
+                case 2:  GEN(g_41); break;
+                default: GEN(g_40); break;
+                }
+                break;
+            case XFACE_WIDTH:
+                switch (j) {
+                case 1:  GEN(g_32); break;
+                case 2:  GEN(g_31); break;
+                default: GEN(g_30); break;
+                }
+                break;
+            default:
+                switch (j) {
+                case 1:  GEN(g_02); break;
+                case 2:  GEN(g_01); break;
+                default: GEN(g_00); break;
+                }
+                break;
+            }
+        }
+    }
+}

libavcodec/xface.h

@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 1990 James Ashton - Sydney University
+ * Copyright (c) 2012 Stefano Sabatini
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * X-Face common definitions.
+ */
+
+#include <stdint.h>
+
+/* define the face size - 48x48x1 */
+#define XFACE_WIDTH  48
+#define XFACE_HEIGHT 48
+#define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT)
+
+/* compressed output uses the full range of printable characters.
+ * In ASCII these are in a contiguous block so we just need to know
+ * the first and last. The total number of printables is needed too. */
+#define XFACE_FIRST_PRINT '!'
+#define XFACE_LAST_PRINT '~'
+#define XFACE_PRINTS (XFACE_LAST_PRINT - XFACE_FIRST_PRINT + 1)
+
+/*
+ * Image is encoded as a big integer, using characters from '~' to
+ * '!', for a total of 92 symbols. In order to express 48x48=2304
+ * bits, we need a total of 354 digits, as given by:
+ * ceil(lg_92(2^2304)) = 354
+ */
+#define XFACE_MAX_DIGITS 354
+
+#define XFACE_BITSPERWORD 8
+#define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD)
+#define XFACE_WORDMASK (XFACE_WORDCARRY - 1)
+
+#define XFACE_MAX_WORDS ((XFACE_PIXELS * 2 + XFACE_BITSPERWORD - 1) / XFACE_BITSPERWORD)
+
+/* Portable, very large unsigned integer arithmetic is needed.
+ * Implementation uses arrays of WORDs. */
+typedef struct {
+    int nb_words;
+    uint8_t words[XFACE_MAX_WORDS];
+} BigInt;
+
+/**
+ * Add a to b storing the result in b.
+ */
+void ff_big_add(BigInt *b, uint8_t a);
+
+/**
+ * Divide b by a storing the result in b and the remainder in the word
+ * pointed to by r.
+ */
+void ff_big_div(BigInt *b, uint8_t a, uint8_t *r);
+
+/**
+ * Multiply a by b storing the result in b.
+ */
+void ff_big_mul(BigInt *b, uint8_t a);
+
+/* Each face is encoded using 9 octrees of 16x16 each. Each level of the
+ * trees has varying probabilities of being white, grey or black.
+ * The table below is based on sampling many faces */
+enum XFaceColor { XFACE_COLOR_BLACK = 0, XFACE_COLOR_GREY, XFACE_COLOR_WHITE };
+
+/* Data of varying probabilities are encoded by a value in the range 0 - 255.
+ * The probability of the data determines the range of possible encodings.
+ * Offset gives the first possible encoding of the range. */
+typedef struct {
+    int range;
+    int offset;
+} ProbRange;
+
+extern const ProbRange ff_xface_probranges_per_level[4][3];
+
+extern const ProbRange ff_xface_probranges_2x2[16];
+
+void ff_xface_generate_face(uint8_t *dst, uint8_t * const src);

libavcodec/xfacedec.c

@@ -0,0 +1,207 @@
+/*
+ * Copyright (c) 1990 James Ashton - Sydney University
+ * Copyright (c) 2012 Stefano Sabatini
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * X-Face decoder, based on libcompface, by James Ashton.
+ */
+
+#include "libavutil/pixdesc.h"
+#include "avcodec.h"
+#include "bytestream.h"
+#include "xface.h"
+
+static int pop_integer(BigInt *b, const ProbRange *pranges)
+{
+    uint8_t r;
+    int i;
+
+    /* extract the last byte into r, and shift right b by 8 bits */
+    ff_big_div(b, 0, &r);
+
+    i = 0;
+    while (r < pranges->offset || r >= pranges->range + pranges->offset) {
+        pranges++;
+        i++;
+    }
+    ff_big_mul(b, pranges->range);
+    ff_big_add(b, r - pranges->offset);
+    return i;
+}
+
+static void pop_greys(BigInt *b, char *bitmap, int w, int h)
+{
+    if (w > 3) {
+        w /= 2;
+        h /= 2;
+        pop_greys(b, bitmap,                       w, h);
+        pop_greys(b, bitmap + w,                   w, h);
+        pop_greys(b, bitmap + XFACE_WIDTH * h,     w, h);
+        pop_greys(b, bitmap + XFACE_WIDTH * h + w, w, h);
+    } else {
+        w = pop_integer(b, ff_xface_probranges_2x2);
+        if (w & 1) bitmap[0]               = 1;
+        if (w & 2) bitmap[1]               = 1;
+        if (w & 4) bitmap[XFACE_WIDTH]     = 1;
+        if (w & 8) bitmap[XFACE_WIDTH + 1] = 1;
+    }
+}
+
+static void decode_block(BigInt *b, char *bitmap, int w, int h, int level)
+{
+    switch (pop_integer(b, &ff_xface_probranges_per_level[level][0])) {
+    case XFACE_COLOR_WHITE:
+        return;
+    case XFACE_COLOR_BLACK:
+        pop_greys(b, bitmap, w, h);
+        return;
+    default:
+        w /= 2;
+        h /= 2;
+        level++;
+        decode_block(b, bitmap,                       w, h, level);
+        decode_block(b, bitmap + w,                   w, h, level);
+        decode_block(b, bitmap + h * XFACE_WIDTH,     w, h, level);
+        decode_block(b, bitmap + w + h * XFACE_WIDTH, w, h, level);
+        return;
+    }
+}
+
+typedef struct XFaceContext {
+    AVFrame frame;
+    uint8_t bitmap[XFACE_PIXELS]; ///< image used internally for decoding
+} XFaceContext;
+
+static av_cold int xface_decode_init(AVCodecContext *avctx)
+{
+    XFaceContext *xface = avctx->priv_data;
+
+    avcodec_get_frame_defaults(&xface->frame);
+
+    if (avctx->width || avctx->height) {
+        if (avctx->width != XFACE_WIDTH || avctx->height != XFACE_HEIGHT) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Size value %dx%d not supported, only accepts a size of %dx%d\n",
+                   avctx->width, avctx->height, XFACE_WIDTH, XFACE_HEIGHT);
+            return AVERROR(EINVAL);
+        }
+    }
+
+    avctx->width   = XFACE_WIDTH;
+    avctx->height  = XFACE_HEIGHT;
+    avctx->pix_fmt = AV_PIX_FMT_MONOWHITE;
+
+    return 0;
+}
+
+static av_cold int xface_decode_close(AVCodecContext *avctx)
+{
+    XFaceContext *xface = avctx->priv_data;
+
+    if (xface->frame.data[0])
+        avctx->release_buffer(avctx, &xface->frame);
+
+    return 0;
+}
+
+static int xface_decode_frame(AVCodecContext *avctx,
+                              void *data, int *data_size,
+                              AVPacket *avpkt)
+{
+    XFaceContext *xface = avctx->priv_data;
+    int ret, i, j, k;
+    uint8_t byte;
+    BigInt b = {0};
+    char *buf;
+    int64_t c;
+
+    if (xface->frame.data[0])
+        avctx->release_buffer(avctx, &xface->frame);
+    xface->frame.data[0] = NULL;
+    if ((ret = avctx->get_buffer(avctx, &xface->frame)) < 0)
+        return ret;
+    xface->frame.reference = 0;
+
+    for (i = 0, k = 0; avpkt->data[i] && i < avpkt->size; i++) {
+        c = avpkt->data[i];
+
+        /* ignore invalid digits */
+        if (c < XFACE_FIRST_PRINT || c > XFACE_LAST_PRINT)
+            continue;
+
+        if (++k > XFACE_MAX_DIGITS) {
+            av_log(avctx, AV_LOG_WARNING,
+                   "Buffer is longer than expected, truncating at byte %d\n", i);
+            break;
+        }
+        ff_big_mul(&b, XFACE_PRINTS);
+        ff_big_add(&b, c - XFACE_FIRST_PRINT);
+    }
+
+    /* decode image and put it in bitmap */
+    memset(xface->bitmap, 0, XFACE_PIXELS);
+    buf = xface->bitmap;
+    decode_block(&b, buf,                         16, 16, 0);
+    decode_block(&b, buf + 16,                    16, 16, 0);
+    decode_block(&b, buf + 32,                    16, 16, 0);
+    decode_block(&b, buf + XFACE_WIDTH * 16,      16, 16, 0);
+    decode_block(&b, buf + XFACE_WIDTH * 16 + 16, 16, 16, 0);
+    decode_block(&b, buf + XFACE_WIDTH * 16 + 32, 16, 16, 0);
+    decode_block(&b, buf + XFACE_WIDTH * 32     , 16, 16, 0);
+    decode_block(&b, buf + XFACE_WIDTH * 32 + 16, 16, 16, 0);
+    decode_block(&b, buf + XFACE_WIDTH * 32 + 32, 16, 16, 0);
+
+    ff_xface_generate_face(xface->bitmap, xface->bitmap);
+
+    /* convert image from 1=black 0=white bitmap to MONOWHITE */
+    buf = xface->frame.data[0];
+    for (i = 0, j = 0, k = 0, byte = 0; i < XFACE_PIXELS; i++) {
+        byte += xface->bitmap[i];
+        if (k == 7) {
+            buf[j++] = byte;
+            byte = k = 0;
+        } else {
+            k++;
+            byte <<= 1;
+        }
+        if (j == XFACE_WIDTH/8) {
+            j = 0;
+            buf += xface->frame.linesize[0];
+        }
+    }
+
+    *data_size = sizeof(AVFrame);
+    *(AVFrame*)data = xface->frame;
+
+    return avpkt->size;
+}
+
+AVCodec ff_xface_decoder = {
+    .name           = "xface",
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_XFACE,
+    .priv_data_size = sizeof(XFaceContext),
+    .init           = xface_decode_init,
+    .close          = xface_decode_close,
+    .decode         = xface_decode_frame,
+    .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_MONOWHITE, AV_PIX_FMT_NONE },
+    .long_name      = NULL_IF_CONFIG_SMALL("X-face image"),
+};

libavcodec/xfaceenc.c

@@ -0,0 +1,237 @@
+/*
+ * Copyright (c) 1990 James Ashton - Sydney University
+ * Copyright (c) 2012 Stefano Sabatini
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * X-Face encoder, based on libcompface, by James Ashton.
+ */
+
+#include "xface.h"
+#include "avcodec.h"
+#include "internal.h"
+
+typedef struct XFaceContext {
+    AVClass *class;
+    uint8_t bitmap[XFACE_PIXELS]; ///< image used internally for decoding
+    int max_line_len;             ///< max line length for compressed data
+    int set_header;               ///< set X-Face header in the output
+} XFaceContext;
+
+static int all_same(char *bitmap, int w, int h)
+{
+    char val, *row;
+    int x;
+
+    val = *bitmap;
+    while (h--) {
+        row = bitmap;
+        x = w;
+        while (x--)
+            if (*(row++) != val)
+                return 0;
+        bitmap += XFACE_WIDTH;
+    }
+    return 1;
+}
+
+static int all_black(char *bitmap, int w, int h)
+{
+    if (w > 3) {
+        w /= 2;
+        h /= 2;
+        return (all_black(bitmap, w, h) && all_black(bitmap + w, w, h) &&
+                all_black(bitmap + XFACE_WIDTH * h, w, h) &&
+                all_black(bitmap + XFACE_WIDTH * h + w, w, h));
+    } else {
+        /* at least one pixel in the 2x2 grid is non-zero */
+        return *bitmap || *(bitmap + 1) ||
+               *(bitmap + XFACE_WIDTH) || *(bitmap + XFACE_WIDTH + 1);
+    }
+}
+
+static int all_white(char *bitmap, int w, int h)
+{
+    return *bitmap == 0 && all_same(bitmap, w, h);
+}
+
+typedef struct {
+    const ProbRange *prob_ranges[XFACE_PIXELS*2];
+    int prob_ranges_idx;
+} ProbRangesQueue;
+
+static inline int pq_push(ProbRangesQueue *pq, const ProbRange *p)
+{
+    if (pq->prob_ranges_idx >= XFACE_PIXELS * 2 - 1)
+        return -1;
+    pq->prob_ranges[pq->prob_ranges_idx++] = p;
+    return 0;
+}
+
+static void push_greys(ProbRangesQueue *pq, char *bitmap, int w, int h)
+{
+    if (w > 3) {
+        w /= 2;
+        h /= 2;
+        push_greys(pq, bitmap,                       w, h);
+        push_greys(pq, bitmap + w,                   w, h);
+        push_greys(pq, bitmap + XFACE_WIDTH * h,     w, h);
+        push_greys(pq, bitmap + XFACE_WIDTH * h + w, w, h);
+    } else {
+        const ProbRange *p = ff_xface_probranges_2x2 +
+                 *bitmap +
+            2 * *(bitmap + 1) +
+            4 * *(bitmap + XFACE_WIDTH) +
+            8 * *(bitmap + XFACE_WIDTH + 1);
+        pq_push(pq, p);
+    }
+}
+
+static void encode_block(char *bitmap, int w, int h, int level, ProbRangesQueue *pq)
+{
+    if (all_white(bitmap, w, h)) {
+        pq_push(pq, &ff_xface_probranges_per_level[level][XFACE_COLOR_WHITE]);
+    } else if (all_black(bitmap, w, h)) {
+        pq_push(pq, &ff_xface_probranges_per_level[level][XFACE_COLOR_BLACK]);
+        push_greys(pq, bitmap, w, h);
+    } else {
+        pq_push(pq, &ff_xface_probranges_per_level[level][XFACE_COLOR_GREY]);
+        w /= 2;
+        h /= 2;
+        level++;
+        encode_block(bitmap,                       w, h, level, pq);
+        encode_block(bitmap + w,                   w, h, level, pq);
+        encode_block(bitmap + h * XFACE_WIDTH,     w, h, level, pq);
+        encode_block(bitmap + w + h * XFACE_WIDTH, w, h, level, pq);
+    }
+}
+
+static av_cold int xface_encode_init(AVCodecContext *avctx)
+{
+    avctx->coded_frame = avcodec_alloc_frame();
+    if (!avctx->coded_frame)
+        return AVERROR(ENOMEM);
+    avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
+
+    return 0;
+}
+
+static void push_integer(BigInt *b, const ProbRange *prange)
+{
+    uint8_t r;
+
+    ff_big_div(b, prange->range, &r);
+    ff_big_mul(b, 0);
+    ff_big_add(b, r + prange->offset);
+}
+
+static int xface_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
+                              const AVFrame *frame, int *got_packet)
+{
+    XFaceContext *xface = avctx->priv_data;
+    ProbRangesQueue pq = {{ 0 }, 0};
+    uint8_t bitmap_copy[XFACE_PIXELS];
+    BigInt b = {0};
+    int i, j, k, ret = 0;
+    const uint8_t *buf;
+    uint8_t *p;
+    char intbuf[XFACE_MAX_DIGITS];
+
+    if (avctx->width || avctx->height) {
+        if (avctx->width != XFACE_WIDTH || avctx->height != XFACE_HEIGHT) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Size value %dx%d not supported, only accepts a size of %dx%d\n",
+                   avctx->width, avctx->height, XFACE_WIDTH, XFACE_HEIGHT);
+            return AVERROR(EINVAL);
+        }
+    }
+    avctx->width  = XFACE_WIDTH;
+    avctx->height = XFACE_HEIGHT;
+
+    /* convert image from MONOWHITE to 1=black 0=white bitmap */
+    buf = frame->data[0];
+    for (i = 0, j = 0; i < XFACE_PIXELS; ) {
+        for (k = 0; k < 8; k++)
+            xface->bitmap[i++] = (buf[j]>>(7-k))&1;
+        if (++j == XFACE_WIDTH/8) {
+            buf += frame->linesize[0];
+            j = 0;
+        }
+    }
+
+    /* create a copy of bitmap */
+    memcpy(bitmap_copy, xface->bitmap, XFACE_PIXELS);
+    ff_xface_generate_face(xface->bitmap, bitmap_copy);
+
+    encode_block(xface->bitmap,                         16, 16, 0, &pq);
+    encode_block(xface->bitmap + 16,                    16, 16, 0, &pq);
+    encode_block(xface->bitmap + 32,                    16, 16, 0, &pq);
+    encode_block(xface->bitmap + XFACE_WIDTH * 16,      16, 16, 0, &pq);
+    encode_block(xface->bitmap + XFACE_WIDTH * 16 + 16, 16, 16, 0, &pq);
+    encode_block(xface->bitmap + XFACE_WIDTH * 16 + 32, 16, 16, 0, &pq);
+    encode_block(xface->bitmap + XFACE_WIDTH * 32,      16, 16, 0, &pq);
+    encode_block(xface->bitmap + XFACE_WIDTH * 32 + 16, 16, 16, 0, &pq);
+    encode_block(xface->bitmap + XFACE_WIDTH * 32 + 32, 16, 16, 0, &pq);
+
+    while (pq.prob_ranges_idx > 0)
+        push_integer(&b, pq.prob_ranges[--pq.prob_ranges_idx]);
+
+    /* write the inverted big integer in b to intbuf */
+    i = 0;
+    while (b.nb_words) {
+        uint8_t r;
+        ff_big_div(&b, XFACE_PRINTS, &r);
+        intbuf[i++] = r + XFACE_FIRST_PRINT;
+    }
+
+    if ((ret = ff_alloc_packet2(avctx, pkt, i+2)) < 0)
+        return ret;
+
+    /* revert the number, and close the buffer */
+    p = pkt->data;
+    while (--i >= 0)
+        *(p++) = intbuf[i];
+    *(p++) = '\n';
+    *(p++) = 0;
+
+    pkt->flags |= AV_PKT_FLAG_KEY;
+    *got_packet = 1;
+
+    return 0;
+}
+
+static av_cold int xface_encode_close(AVCodecContext *avctx)
+{
+    av_freep(&avctx->coded_frame);
+
+    return 0;
+}
+
+AVCodec ff_xface_encoder = {
+    .name           = "xface",
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_XFACE,
+    .priv_data_size = sizeof(XFaceContext),
+    .init           = xface_encode_init,
+    .close          = xface_encode_close,
+    .encode2        = xface_encode_frame,
+    .pix_fmts       = (const enum PixelFormat[]) { AV_PIX_FMT_MONOWHITE, AV_PIX_FMT_NONE },
+    .long_name      = NULL_IF_CONFIG_SMALL("X-face image"),
+};

libavformat/img2.c

@@ -74,6 +74,7 @@ static const IdStrMap img_tags[] = {
     { AV_CODEC_ID_PICTOR    , "pic"},
     { AV_CODEC_ID_V210X     , "yuv10"},
     { AV_CODEC_ID_XBM       , "xbm"},
+    { AV_CODEC_ID_XFACE     , "xface"},
     { AV_CODEC_ID_XWD       , "xwd"},
     { AV_CODEC_ID_NONE      , NULL}
 };

libavformat/img2enc.c

@@ -152,7 +152,7 @@ AVOutputFormat ff_image2_muxer = {
     .long_name      = NULL_IF_CONFIG_SMALL("image2 sequence"),
     .extensions     = "bmp,dpx,jls,jpeg,jpg,ljpg,pam,pbm,pcx,pgm,pgmyuv,png,"
                       "ppm,sgi,tga,tif,tiff,jp2,j2c,xwd,sun,ras,rs,im1,im8,im24,"
-                      "sunras,xbm",
+                      "sunras,xbm,xface",
     .priv_data_size = sizeof(VideoMuxData),
     .video_codec    = AV_CODEC_ID_MJPEG,
     .write_header   = write_header,

libavformat/version.h

@@ -31,7 +31,7 @@
 
 #define LIBAVFORMAT_VERSION_MAJOR 54
 #define LIBAVFORMAT_VERSION_MINOR 32
-#define LIBAVFORMAT_VERSION_MICRO 100
+#define LIBAVFORMAT_VERSION_MICRO 101
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \