@@ -23,6 +23,7 @@ version 10:

 - support for slice multithreading in libavfilter

 - VC-1 interlaced B-frame support

 - support for WavPack muxing (raw and in Matroska)

+- Go2Webinar decoder

 version 9:

@@ -1575,6 +1575,7 @@ flv_decoder_select="h263_decoder"

 flv_encoder_select="h263_encoder"

 fourxm_decoder_select="dsputil"

 fraps_decoder_select="dsputil huffman"

+g2m_decoder_select="dsputil zlib"

 h261_decoder_select="error_resilience mpegvideo"

 h261_encoder_select="aandcttables mpegvideoenc"

 h263_decoder_select="error_resilience h263_parser mpegvideo"

@@ -507,6 +507,8 @@ following image formats are supported:

     @tab Sorenson H.263 used in Flash

 @item Forward Uncompressed   @tab     @tab  X

 @item Fraps                  @tab     @tab  X

+@item Go2Webinar             @tab     @tab  X

+    @tab fourcc: G2M4

 @item H.261                  @tab  X  @tab  X

 @item H.263 / H.263-1996     @tab  X  @tab  X

 @item H.263+ / H.263-1998 / H.263 version 2  @tab  X  @tab  X

@@ -177,6 +177,7 @@ OBJS-$(CONFIG_FLIC_DECODER)            += flicvideo.o

 OBJS-$(CONFIG_FOURXM_DECODER)          += 4xm.o

 OBJS-$(CONFIG_FRAPS_DECODER)           += fraps.o

 OBJS-$(CONFIG_FRWU_DECODER)            += frwu.o

+OBJS-$(CONFIG_G2M_DECODER)             += g2meet.o mjpeg.o

 OBJS-$(CONFIG_G723_1_DECODER)          += g723_1.o acelp_vectors.o \

                                           celp_filters.o

 OBJS-$(CONFIG_GIF_DECODER)             += gifdec.o lzw.o

@@ -146,6 +146,7 @@ void avcodec_register_all(void)

     REGISTER_DECODER(FOURXM,            fourxm);

     REGISTER_DECODER(FRAPS,             fraps);

     REGISTER_DECODER(FRWU,              frwu);

+    REGISTER_DECODER(G2M,               g2m);

     REGISTER_ENCDEC (GIF,               gif);

     REGISTER_ENCDEC (H261,              h261);

     REGISTER_ENCDEC (H263,              h263);

@@ -270,6 +270,7 @@ enum AVCodecID {

     AV_CODEC_ID_VP9,

     AV_CODEC_ID_AIC,

     AV_CODEC_ID_ESCAPE130,

+    AV_CODEC_ID_G2M,

     /* various PCM "codecs" */

     AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs

@@ -1221,6 +1221,13 @@ static const AVCodecDescriptor codec_descriptors[] = {

         .long_name = NULL_IF_CONFIG_SMALL("Escape 130"),

         .props     = AV_CODEC_PROP_LOSSY,

     },

+    {

+        .id        = AV_CODEC_ID_G2M,

+        .type      = AVMEDIA_TYPE_VIDEO,

+        .name      = "g2m",

+        .long_name = NULL_IF_CONFIG_SMALL("Go2Meeting"),

+        .props     = AV_CODEC_PROP_LOSSY,

+    },

     /* various PCM "codecs" */

     {

new file mode 100644

@@ -0,0 +1,825 @@

+/*

+ * Go2Webinar decoder

+ * Copyright (c) 2012 Konstantin Shishkov

+ *

+ * This file is part of Libav.

+ *

+ * Libav 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.

+ *

+ * Libav 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 Libav; if not, write to the Free Software

+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

+ */

+

+/**

+ * @file

+ * Go2Webinar decoder

+ */

+

+#include <zlib.h>

+

+#include "libavutil/intreadwrite.h"

+#include "avcodec.h"

+#include "bytestream.h"

+#include "dsputil.h"

+#include "get_bits.h"

+#include "internal.h"

+#include "mjpeg.h"

+

+enum ChunkType {

+    FRAME_INFO = 0xC8,

+    TILE_DATA,

+    CURSOR_POS,

+    CURSOR_SHAPE,

+    CHUNK_CC,

+    CHUNK_CD

+};

+

+enum Compression {

+    COMPR_EPIC_J_B = 2,

+    COMPR_KEMPF_J_B,

+};

+

+static const uint8_t luma_quant[64] = {

+     8,  6,  5,  8, 12, 20, 26, 31,

+     6,  6,  7, 10, 13, 29, 30, 28,

+     7,  7,  8, 12, 20, 29, 35, 28,

+     7,  9, 11, 15, 26, 44, 40, 31,

+     9, 11, 19, 28, 34, 55, 52, 39,

+    12, 18, 28, 32, 41, 52, 57, 46,

+    25, 32, 39, 44, 52, 61, 60, 51,

+    36, 46, 48, 49, 56, 50, 52, 50

+};

+

+static const uint8_t chroma_quant[64] = {

+     9,  9, 12, 24, 50, 50, 50, 50,

+     9, 11, 13, 33, 50, 50, 50, 50,

+    12, 13, 28, 50, 50, 50, 50, 50,

+    24, 33, 50, 50, 50, 50, 50, 50,

+    50, 50, 50, 50, 50, 50, 50, 50,

+    50, 50, 50, 50, 50, 50, 50, 50,

+    50, 50, 50, 50, 50, 50, 50, 50,

+    50, 50, 50, 50, 50, 50, 50, 50,

+};

+

+typedef struct JPGContext {

+    DSPContext dsp;

+    ScanTable  scantable;

+

+    VLC        dc_vlc[2], ac_vlc[2];

+    int        prev_dc[3];

+    DECLARE_ALIGNED(16, int16_t, block)[6][64];

+

+    uint8_t    *buf;

+} JPGContext;

+

+typedef struct G2MContext {

+    JPGContext jc;

+    int        version;

+

+    int        compression;

+    int        width, height, bpp;

+    int        tile_width, tile_height;

+    int        tiles_x, tiles_y, tile_x, tile_y;

+

+    int        got_header;

+

+    uint8_t    *framebuf;

+    int        framebuf_stride, old_width, old_height;

+

+    uint8_t    *synth_tile, *jpeg_tile;

+    int        tile_stride, old_tile_w, old_tile_h;

+

+    uint8_t    *kempf_buf, *kempf_flags;

+

+    uint8_t    *cursor;

+    int        cursor_stride;

+    int        cursor_fmt;

+    int        cursor_w, cursor_h, cursor_x, cursor_y;

+    int        cursor_hot_x, cursor_hot_y;

+} G2MContext;

+

+static av_cold int build_vlc(VLC *vlc, const uint8_t *bits_table,

+                             const uint8_t *val_table, int nb_codes,

+                             int is_ac)

+{

+    uint8_t  huff_size[256] = { 0 };

+    uint16_t huff_code[256];

+    uint16_t huff_sym[256];

+    int i;

+

+    ff_mjpeg_build_huffman_codes(huff_size, huff_code, bits_table, val_table);

+

+    for (i = 0; i < 256; i++)

+        huff_sym[i] = i + 16 * is_ac;

+

+    if (is_ac)

+        huff_sym[0] = 16 * 256;

+

+    return ff_init_vlc_sparse(vlc, 9, nb_codes, huff_size, 1, 1,

+                              huff_code, 2, 2, huff_sym, 2, 2, 0);

+}

+

+static av_cold int jpg_init(AVCodecContext *avctx, JPGContext *c)

+{

+    int ret;

+

+    ret = build_vlc(&c->dc_vlc[0], avpriv_mjpeg_bits_dc_luminance,

+                    avpriv_mjpeg_val_dc, 12, 0);

+    if (ret)

+        return ret;

+    ret = build_vlc(&c->dc_vlc[1], avpriv_mjpeg_bits_dc_chrominance,

+                    avpriv_mjpeg_val_dc, 12, 0);

+    if (ret)

+        return ret;

+    ret = build_vlc(&c->ac_vlc[0], avpriv_mjpeg_bits_ac_luminance,

+                    avpriv_mjpeg_val_ac_luminance, 251, 1);

+    if (ret)

+        return ret;

+    ret = build_vlc(&c->ac_vlc[1], avpriv_mjpeg_bits_ac_chrominance,

+                    avpriv_mjpeg_val_ac_chrominance, 251, 1);

+    if (ret)

+        return ret;

+

+    ff_dsputil_init(&c->dsp, avctx);

+    ff_init_scantable(c->dsp.idct_permutation, &c->scantable,

+                      ff_zigzag_direct);

+

+    return 0;

+}

+

+static av_cold void jpg_free_context(JPGContext *ctx)

+{

+    int i;

+

+    for (i = 0; i < 2; i++) {

+        ff_free_vlc(&ctx->dc_vlc[i]);

+        ff_free_vlc(&ctx->ac_vlc[i]);

+    }

+

+    av_freep(&ctx->buf);

+}

+

+static void jpg_unescape(const uint8_t *src, int src_size,

+                         uint8_t *dst, int *dst_size)

+{

+    const uint8_t *src_end = src + src_size;

+    uint8_t *dst_start = dst;

+

+    while (src < src_end) {

+        uint8_t x = *src++;

+

+        *dst++ = x;

+

+        if (x == 0xFF && !*src)

+            src++;

+    }

+    *dst_size = dst - dst_start;

+}

+

+static int jpg_decode_block(JPGContext *c, GetBitContext *gb,

+                            int plane, int16_t *block)

+{

+    int dc, val, pos;

+    const int is_chroma = !!plane;

+    const uint8_t *qmat = is_chroma ? chroma_quant : luma_quant;

+

+    c->dsp.clear_block(block);

+    dc = get_vlc2(gb, c->dc_vlc[is_chroma].table, 9, 3);

+    if (dc < 0)

+        return AVERROR_INVALIDDATA;

+    if (dc)

+        dc = get_xbits(gb, dc);

+    dc = dc * qmat[0] + c->prev_dc[plane];

+    block[0] = dc;

+    c->prev_dc[plane] = dc;

+

+    pos = 0;

+    while (pos < 63) {

+        val = get_vlc2(gb, c->ac_vlc[is_chroma].table, 9, 3);

+        if (val < 0)

+            return AVERROR_INVALIDDATA;

+        pos += val >> 4;

+        val &= 0xF;

+        if (pos > 63)

+            return val ? AVERROR_INVALIDDATA : 0;

+        if (val) {

+            int nbits = val;

+

+            val = get_xbits(gb, nbits);

+            val *= qmat[ff_zigzag_direct[pos]];

+            block[c->scantable.permutated[pos]] = val;

+        }

+    }

+    return 0;

+}

+

+static inline void yuv2rgb(uint8_t *out, int Y, int U, int V)

+{

+    out[0] = av_clip_uint8(Y + (             91881 * V + 32768 >> 16));

+    out[1] = av_clip_uint8(Y + (-22554 * U - 46802 * V + 32768 >> 16));

+    out[2] = av_clip_uint8(Y + (116130 * U             + 32768 >> 16));

+}

+

+static int jpg_decode_data(JPGContext *c, int width, int height,

+                           const uint8_t *src, int src_size,

+                           uint8_t *dst, int dst_stride,

+                           const uint8_t *mask, int mask_stride, int num_mbs,

+                           int swapuv)

+{

+    GetBitContext gb;

+    uint8_t *tmp;

+    int mb_w, mb_h, mb_x, mb_y, i, j;

+    int bx, by;

+    int unesc_size;

+    int ret;

+

+    tmp = av_realloc(c->buf, src_size + FF_INPUT_BUFFER_PADDING_SIZE);

+    if (!tmp)

+        return AVERROR(ENOMEM);

+    c->buf = tmp;

+    jpg_unescape(src, src_size, c->buf, &unesc_size);

+    memset(c->buf + unesc_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);

+    init_get_bits(&gb, c->buf, unesc_size * 8);

+

+    width = FFALIGN(width, 16);

+    mb_w  =  width        >> 4;

+    mb_h  = (height + 15) >> 4;

+

+    if (!num_mbs)

+        num_mbs = mb_w * mb_h;

+

+    for (i = 0; i < 3; i++)

+        c->prev_dc[i] = 1024;

+    bx = by = 0;

+    for (mb_y = 0; mb_y < mb_h; mb_y++) {

+        for (mb_x = 0; mb_x < mb_w; mb_x++) {

+            if (mask && !mask[mb_x]) {

+                bx += 16;

+                continue;

+            }

+            for (j = 0; j < 2; j++) {

+                for (i = 0; i < 2; i++) {

+                    if ((ret = jpg_decode_block(c, &gb, 0,

+                                                c->block[i + j * 2])) != 0)

+                        return ret;

+                    c->dsp.idct(c->block[i + j * 2]);

+                }

+            }

+            for (i = 1; i < 3; i++) {

+                if ((ret = jpg_decode_block(c, &gb, i, c->block[i + 3])) != 0)

+                    return ret;

+                c->dsp.idct(c->block[i + 3]);

+            }

+

+            for (j = 0; j < 16; j++) {

+                uint8_t *out = dst + bx * 3 + (by + j) * dst_stride;

+                for (i = 0; i < 16; i++) {

+                    int Y, U, V;

+

+                    Y = c->block[(j >> 3) * 2 + (i >> 3)][(i & 7) + (j & 7) * 8];

+                    U = c->block[4 ^ swapuv][(i >> 1) + (j >> 1) * 8] - 128;

+                    V = c->block[5 ^ swapuv][(i >> 1) + (j >> 1) * 8] - 128;

+                    yuv2rgb(out + i * 3, Y, U, V);

+                }

+            }

+

+            if (!--num_mbs)

+                return 0;

+            bx += 16;

+        }

+        bx  = 0;

+        by += 16;

+        if (mask)

+            mask += mask_stride;

+    }

+

+    return 0;

+}

+

+static void kempf_restore_buf(const uint8_t *src, int len,

+                              uint8_t *dst, int stride,

+                              const uint8_t *jpeg_tile, int tile_stride,

+                              int width, int height,

+                              const uint8_t *pal, int npal, int tidx)

+{

+    GetBitContext gb;

+    int i, j, nb, col;

+

+    init_get_bits(&gb, src, len * 8);

+

+    if (npal <= 2)       nb = 1;

+    else if (npal <= 4)  nb = 2;

+    else if (npal <= 16) nb = 4;

+    else                 nb = 8;

+

+    for (j = 0; j < height; j++, dst += stride, jpeg_tile += tile_stride) {

+        if (get_bits(&gb, 8))

+            continue;

+        for (i = 0; i < width; i++) {

+            col = get_bits(&gb, nb);

+            if (col != tidx)

+                memcpy(dst + i * 3, pal + col * 3, 3);

+            else

+                memcpy(dst + i * 3, jpeg_tile + i * 3, 3);

+        }

+    }

+}

+

+static int kempf_decode_tile(G2MContext *c, int tile_x, int tile_y,

+                             const uint8_t *src, int src_size)

+{

+    int width, height;

+    int hdr, zsize, npal, tidx = -1, ret;

+    int i, j;

+    const uint8_t *src_end = src + src_size;

+    uint8_t pal[768], transp[3];

+    uLongf dlen = (c->tile_width + 1) * c->tile_height;

+    int sub_type;

+    int nblocks, cblocks, bstride;

+    int bits, bitbuf, coded;

+    uint8_t *dst = c->framebuf + tile_x * c->tile_width * 3 +

+                   tile_y * c->tile_height * c->framebuf_stride;

+

+    if (src_size < 2)

+        return AVERROR_INVALIDDATA;

+

+    width  = FFMIN(c->width  - tile_x * c->tile_width,  c->tile_width);

+    height = FFMIN(c->height - tile_y * c->tile_height, c->tile_height);

+

+    hdr = *src++;

+    sub_type = hdr >> 5;

+    if (sub_type == 0) {

+        int j;

+        memcpy(transp, src, 3);

+        src += 3;

+        for (j = 0; j < height; j++, dst += c->framebuf_stride)

+            for (i = 0; i < width; i++)

+                memcpy(dst + i * 3, transp, 3);

+        return 0;

+    } else if (sub_type == 1) {

+        return jpg_decode_data(&c->jc, width, height, src, src_end - src,

+                               dst, c->framebuf_stride, NULL, 0, 0, 0);

+    }

+

+    if (sub_type != 2) {

+        memcpy(transp, src, 3);

+        src += 3;

+    }

+    npal = *src++ + 1;

+    memcpy(pal, src, npal * 3); src += npal * 3;

+    if (sub_type != 2) {

+        for (i = 0; i < npal; i++) {

+            if (!memcmp(pal + i * 3, transp, 3)) {

+               tidx = i;

+               break;

+            }

+        }

+    }

+

+    if (src_end - src < 2)

+        return 0;

+    zsize = (src[0] << 8) | src[1]; src += 2;

+

+    if (src_end - src < zsize)

+        return AVERROR_INVALIDDATA;

+

+    ret = uncompress(c->kempf_buf, &dlen, src, zsize);

+    if (ret)

+        return AVERROR_INVALIDDATA;

+    src += zsize;

+

+    if (sub_type == 2) {

+        kempf_restore_buf(c->kempf_buf, dlen, dst, c->framebuf_stride,

+                          NULL, 0, width, height, pal, npal, tidx);

+        return 0;

+    }

+

+    nblocks = *src++ + 1;

+    cblocks = 0;

+    bstride = FFALIGN(width, 16) >> 4;

+    // blocks are coded LSB and we need normal bitreader for JPEG data

+    bits = 0;

+    for (i = 0; i < (FFALIGN(height, 16) >> 4); i++) {

+        for (j = 0; j < (FFALIGN(width, 16) >> 4); j++) {

+            if (!bits) {

+                bitbuf = *src++;

+                bits   = 8;

+            }

+            coded = bitbuf & 1;

+            bits--;

+            bitbuf >>= 1;

+            cblocks += coded;

+            if (cblocks > nblocks)

+                return AVERROR_INVALIDDATA;

+            c->kempf_flags[j + i * bstride] = coded;

+        }

+    }

+

+    memset(c->jpeg_tile, 0, c->tile_stride * height);

+    jpg_decode_data(&c->jc, width, height, src, src_end - src,

+                    c->jpeg_tile, c->tile_stride,

+                    c->kempf_flags, bstride, nblocks, 0);

+

+    kempf_restore_buf(c->kempf_buf, dlen, dst, c->framebuf_stride,

+                      c->jpeg_tile, c->tile_stride,

+                      width, height, pal, npal, tidx);

+

+    return 0;

+}

+

+static int g2m_init_buffers(G2MContext *c)

+{

+    int aligned_height;

+

+    if (!c->framebuf || c->old_width < c->width || c->height < c->height) {

+        c->framebuf_stride = FFALIGN(c->width * 3, 16);

+        aligned_height     = FFALIGN(c->height,    16);

+        av_free(c->framebuf);

+        c->framebuf = av_mallocz(c->framebuf_stride * aligned_height);

+        if (!c->framebuf)

+            return AVERROR(ENOMEM);

+    }

+    if (!c->synth_tile || !c->jpeg_tile ||

+        c->old_tile_w < c->tile_width ||

+        c->old_tile_h < c->tile_height) {

+        c->tile_stride = FFALIGN(c->tile_width * 3, 16);

+        aligned_height = FFALIGN(c->tile_height,    16);

+        av_free(c->synth_tile);

+        av_free(c->jpeg_tile);

+        c->synth_tile  = av_mallocz(c->tile_stride      * aligned_height);

+        c->jpeg_tile   = av_mallocz(c->tile_stride      * aligned_height);

+        c->kempf_buf   = av_mallocz((c->tile_width + 1) * aligned_height

+                                    + FF_INPUT_BUFFER_PADDING_SIZE);

+        c->kempf_flags = av_mallocz( c->tile_width      * aligned_height);

+        if (!c->synth_tile || !c->jpeg_tile ||

+            !c->kempf_buf || !c->kempf_flags)

+            return AVERROR(ENOMEM);

+    }

+

+    return 0;

+}

+

+static int g2m_load_cursor(G2MContext *c, GetByteContext *gb)

+{

+    int i, j, k;

+    uint8_t *dst;

+    uint32_t bits;

+

+    c->cursor_stride = c->cursor_w * 4;

+    c->cursor        = av_realloc(c->cursor, c->cursor_stride * c->cursor_h);

+    if (!c->cursor)

+        return AVERROR(ENOMEM);

+

+    dst = c->cursor;

+    switch (c->cursor_fmt) {

+    case 1: // old monochrome

+        for (j = 0; j < c->cursor_h; j++) {

+            for (i = 0; i < c->cursor_w; i += 32) {

+                bits = bytestream2_get_be32(gb);

+                for (k = 0; k < 32; k++) {

+                    dst[0] = !!(bits & 0x80000000);

+                    dst += 4;

+                    bits <<= 1;

+                }

+            }

+        }

+

+        dst = c->cursor;

+        for (j = 0; j < c->cursor_h; j++) {

+            for (i = 0; i < c->cursor_w; i += 32) {

+                bits = bytestream2_get_be32(gb);

+                for (k = 0; k < 32; k++) {

+                    int mask_bit = !!(bits & 0x80000000);

+                    switch (dst[0] * 2 + mask_bit) {

+                    case 0:

+                        dst[0] = 0xFF; dst[1] = 0x00;

+                        dst[2] = 0x00; dst[3] = 0x00;

+                        break;

+                    case 1:

+                        dst[0] = 0xFF; dst[1] = 0xFF;

+                        dst[2] = 0xFF; dst[3] = 0xFF;

+                        break;

+                    default:

+                        dst[0] = 0x00; dst[1] = 0x00;

+                        dst[2] = 0x00; dst[3] = 0x00;

+                    }

+                    dst += 4;

+                    bits <<= 1;

+                }

+            }

+        }

+        break;

+    case 32: // full colour

+        /* skip monochrome version of the cursor and decode RGBA instead */

+        bytestream2_skip(gb, c->cursor_h * (FFALIGN(c->cursor_w, 32) >> 3));

+        for (j = 0; j < c->cursor_h; j++) {

+            for (i = 0; i < c->cursor_w; i++) {

+                int val = bytestream2_get_be32(gb);

+                *dst++ = val >>  0;

+                *dst++ = val >>  8;

+                *dst++ = val >> 16;

+                *dst++ = val >> 24;

+            }

+        }

+        break;

+    default:

+        return AVERROR_PATCHWELCOME;

+    }

+    return 0;

+}

+

+#define APPLY_ALPHA(src, new, alpha) \

+    src = (src * (256 - alpha) + new * alpha) >> 8

+

+static void g2m_paint_cursor(G2MContext *c, uint8_t *dst, int stride)

+{

+    int i, j;

+    int x, y, w, h;

+    const uint8_t *cursor;

+

+    if (!c->cursor)

+        return;

+

+    x = c->cursor_x - c->cursor_hot_x;

+    y = c->cursor_y - c->cursor_hot_y;

+

+    cursor = c->cursor;

+    w      = c->cursor_w;

+    h      = c->cursor_h;

+

+    if (x + w > c->width)

+        w = c->width - x;

+    if (y + h > c->height)

+        h = c->height - y;

+    if (x < 0) {

+        w      +=  x;

+        cursor += -x * 4;

+    } else {

+        dst    +=  x * 3;

+    }

+    if (y < 0) {

+        h      +=  y;

+        cursor += -y * c->cursor_stride;

+    } else {

+        dst    +=  y * stride;

+    }

+    if (w < 0 || h < 0)

+        return;

+

+    for (j = 0; j < h; j++) {

+        for (i = 0; i < w; i++) {

+            uint8_t alpha = cursor[i * 4];

+            APPLY_ALPHA(dst[i * 3 + 0], cursor[i * 4 + 1], alpha);

+            APPLY_ALPHA(dst[i * 3 + 1], cursor[i * 4 + 2], alpha);

+            APPLY_ALPHA(dst[i * 3 + 2], cursor[i * 4 + 3], alpha);

+        }

+        dst    += stride;

+        cursor += c->cursor_stride;

+    }

+}

+

+static int g2m_decode_frame(AVCodecContext *avctx, void *data,

+                            int *got_picture_ptr, AVPacket *avpkt)

+{

+    const uint8_t *buf = avpkt->data;

+    int buf_size = avpkt->size;

+    G2MContext *c = avctx->priv_data;

+    AVFrame *pic = data;

+    GetByteContext bc, tbc;

+    int magic;

+    int got_header = 0;

+    uint32_t chunk_size, cur_size;

+    int chunk_type;

+    int i;

+    int ret;

+

+    if (buf_size < 12) {

+        av_log(avctx, AV_LOG_ERROR,

+               "Frame should have at least 12 bytes, got %d instead\n",

+               buf_size);

+        return AVERROR_INVALIDDATA;

+    }

+

+    bytestream2_init(&bc, buf, buf_size);

+

+    magic = bytestream2_get_be32(&bc);

+    if ((magic & ~0xF) != MKBETAG('G', '2', 'M', '0') ||

+        (magic & 0xF) < 2 || (magic & 0xF) > 4) {

+        av_log(avctx, AV_LOG_ERROR, "Wrong magic %08X\n", magic);

+        return AVERROR_INVALIDDATA;

+    }

+

+    if ((magic & 0xF) != 4) {

+        av_log(avctx, AV_LOG_ERROR, "G2M2 and G2M3 are not yet supported\n");

+        return AVERROR(ENOSYS);

+    }

+

+    while (bytestream2_get_bytes_left(&bc) > 5) {

+        chunk_size = bytestream2_get_le32(&bc) - 1;

+        chunk_type = bytestream2_get_byte(&bc);

+        if (chunk_size > bytestream2_get_bytes_left(&bc)) {

+            av_log(avctx, AV_LOG_ERROR, "Invalid chunk size %d type %02X\n",

+                   chunk_size, chunk_type);

+            break;

+        }

+        switch (chunk_type) {

+        case FRAME_INFO:

+            c->got_header = 0;

+            if (chunk_size < 21) {

+                av_log(avctx, AV_LOG_ERROR, "Invalid frame info size %d\n",

+                       chunk_size);

+                break;

+            }

+            c->width  = bytestream2_get_be32(&bc);

+            c->height = bytestream2_get_be32(&bc);

+            if (c->width  < 16 || c->width  > avctx->width ||

+                c->height < 16 || c->height > avctx->height) {

+                av_log(avctx, AV_LOG_ERROR,

+                       "Invalid frame dimensions %dx%d\n",

+                       c->width, c->height);

+                c->width = c->height = 0;

+                bytestream2_skip(&bc, bytestream2_get_bytes_left(&bc));

+            }

+            if (c->width != avctx->width || c->height != avctx->height)

+                avcodec_set_dimensions(avctx, c->width, c->height);

+            c->compression = bytestream2_get_be32(&bc);

+            if (c->compression != 2 && c->compression != 3) {

+                av_log(avctx, AV_LOG_ERROR,

+                       "Unknown compression method %d\n",

+                       c->compression);

+                return AVERROR_PATCHWELCOME;

+            }

+            c->tile_width  = bytestream2_get_be32(&bc);

+            c->tile_height = bytestream2_get_be32(&bc);

+            if (!c->tile_width || !c->tile_height) {

+                av_log(avctx, AV_LOG_ERROR,

+                       "Invalid tile dimensions %dx%d\n",

+                       c->tile_width, c->tile_height);

+                return AVERROR_INVALIDDATA;

+            }

+            c->tiles_x = (c->width  + c->tile_width  - 1) / c->tile_width;

+            c->tiles_y = (c->height + c->tile_height - 1) / c->tile_height;

+            c->bpp = bytestream2_get_byte(&bc);

+            chunk_size -= 21;

+            bytestream2_skip(&bc, chunk_size);

+            if (g2m_init_buffers(c))

+                return AVERROR(ENOMEM);

+            got_header = 1;

+            break;

+        case TILE_DATA:

+            if (!c->tiles_x || !c->tiles_y) {

+                av_log(avctx, AV_LOG_WARNING,

+                       "No frame header - skipping tile\n");

+                bytestream2_skip(&bc, bytestream2_get_bytes_left(&bc));

+                break;

+            }

+            if (chunk_size < 2) {

+                av_log(avctx, AV_LOG_ERROR, "Invalid tile data size %d\n",

+                       chunk_size);

+                break;

+            }

+            c->tile_x = bytestream2_get_byte(&bc);

+            c->tile_y = bytestream2_get_byte(&bc);

+            if (c->tile_x >= c->tiles_x || c->tile_y >= c->tiles_y) {

+                av_log(avctx, AV_LOG_ERROR,

+                       "Invalid tile pos %d,%d (in %dx%d grid)\n",

+                       c->tile_x, c->tile_y, c->tiles_x, c->tiles_y);

+                break;

+            }

+            chunk_size -= 2;

+            ret = 0;

+            switch (c->compression) {

+            case COMPR_EPIC_J_B:

+                av_log(avctx, AV_LOG_ERROR,

+                       "ePIC j-b compression is not implemented yet\n");

+                return AVERROR(ENOSYS);

+            case COMPR_KEMPF_J_B:

+                ret = kempf_decode_tile(c, c->tile_x, c->tile_y,

+                                        buf + bytestream2_tell(&bc),

+                                        chunk_size);

+                break;

+            }

+            if (ret && c->framebuf)

+                av_log(avctx, AV_LOG_ERROR, "Error decoding tile %d,%d\n",

+                       c->tile_x, c->tile_y);

+            bytestream2_skip(&bc, chunk_size);

+            break;

+        case CURSOR_POS:

+            if (chunk_size < 5) {

+                av_log(avctx, AV_LOG_ERROR, "Invalid cursor pos size %d\n",

+                       chunk_size);

+                break;

+            }

+            c->cursor_x = bytestream2_get_be16(&bc);

+            c->cursor_y = bytestream2_get_be16(&bc);

+            bytestream2_skip(&bc, chunk_size - 4);

+            break;

+        case CURSOR_SHAPE:

+            if (chunk_size < 8) {

+                av_log(avctx, AV_LOG_ERROR, "Invalid cursor data size %d\n",

+                       chunk_size);

+                break;

+            }

+            bytestream2_init(&tbc, buf + bytestream2_tell(&bc),

+                             chunk_size - 4);

+            cur_size        = bytestream2_get_be32(&tbc);

+            c->cursor_w     = bytestream2_get_byte(&tbc);

+            c->cursor_h     = bytestream2_get_byte(&tbc);

+            c->cursor_hot_x = bytestream2_get_byte(&tbc);

+            c->cursor_hot_y = bytestream2_get_byte(&tbc);

+            c->cursor_fmt   = bytestream2_get_byte(&tbc);

+            if (cur_size >= chunk_size ||

+                c->cursor_w * c->cursor_h / 4 > cur_size) {

+                av_log(avctx, AV_LOG_ERROR, "Invalid cursor data size %d\n",

+                       chunk_size);

+                break;

+            }

+            g2m_load_cursor(c, &tbc);

+            bytestream2_skip(&bc, chunk_size);

+            break;

+        case CHUNK_CC:

+        case CHUNK_CD:

+            bytestream2_skip(&bc, chunk_size);

+            break;

+        default:

+            av_log(avctx, AV_LOG_WARNING, "Skipping chunk type %02X\n",

+                   chunk_type);

+            bytestream2_skip(&bc, chunk_size);

+        }

+    }

+    if (got_header)

+        c->got_header = 1;

+

+    if (c->width && c->height) {

+        if ((ret = ff_get_buffer(avctx, pic, 0)) < 0) {

+            av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

+            return ret;

+        }

+

+        pic->key_frame = got_header;

+        pic->pict_type = got_header ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;

+

+        for (i = 0; i < avctx->height; i++)

+            memcpy(pic->data[0] + i * pic->linesize[0],

+                   c->framebuf  + i * c->framebuf_stride,

+                   c->width * 3);

+        g2m_paint_cursor(c, pic->data[0], pic->linesize[0]);

+

+        *got_picture_ptr = 1;

+    }

+

+    return buf_size;

+}

+

+static av_cold int g2m_decode_init(AVCodecContext *avctx)

+{

+    G2MContext * const c = avctx->priv_data;

+    int ret;

+

+    if ((ret = jpg_init(avctx, &c->jc)) != 0) {

+        av_log(avctx, AV_LOG_ERROR, "Cannot initialise VLCs\n");

+        jpg_free_context(&c->jc);

+        return AVERROR(ENOMEM);

+    }

+

+    avctx->pix_fmt     = PIX_FMT_RGB24;

+

+    return 0;

+}

+

+static av_cold int g2m_decode_end(AVCodecContext *avctx)

+{

+    G2MContext * const c = avctx->priv_data;

+

+    jpg_free_context(&c->jc);

+

+    av_freep(&c->kempf_buf);

+    av_freep(&c->kempf_flags);

+    av_freep(&c->synth_tile);