tinfoil patch: no array is written to in bulk before counts are

validated; do not free frames that are not allocated; removed all of the
output modes that no one uses and only PAL8 remains

Originally committed as revision 4517 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 85 insertions, 419 deletions

diff --git a/libavcodec/xan.c b/libavcodec/xan.c
index 377a71ef2c..96cc193295 100644
--- a/libavcodec/xan.c
+++ b/libavcodec/xan.c
@@ -20,12 +20,11 @@
 
 /**
  * @file xan.c
- * Xan video decoder for Wing Commander III & IV computer games
+ * Xan video decoder for Wing Commander III computer game
  * by Mario Brito (mbrito@student.dei.uc.pt)
  * and Mike Melanson (melanson@pcisys.net)
  *
- * The xan_wc3 decoder outputs the following colorspaces natively:
- *   PAL8 (default), RGB555, RGB565, RGB24, BGR24, RGBA32, YUV444P
+ * The xan_wc3 decoder outputs PAL8 data.
  */
 
 #include <stdio.h>
@@ -35,77 +34,32 @@
 
 #include "common.h"
 #include "avcodec.h"
-#include "dsputil.h"
-
-#define PALETTE_COUNT 256
-#define PALETTE_CONTROL_SIZE ((256 * 3) + 1)
 
 typedef struct XanContext {
 
     AVCodecContext *avctx;
-    DSPContext dsp;
     AVFrame last_frame;
     AVFrame current_frame;
 
     unsigned char *buf;
     int size;
 
-    unsigned char palette[PALETTE_COUNT * 4];
-
     /* scratch space */
     unsigned char *buffer1;
+    int buffer1_size;
     unsigned char *buffer2;
+    int buffer2_size;
 
-} XanContext;
-
-/* RGB -> YUV conversion stuff */
-#define SCALEFACTOR 65536
-#define CENTERSAMPLE 128
-
-#define COMPUTE_Y(r, g, b) \
-  (unsigned char) \
-  ((y_r_table[r] + y_g_table[g] + y_b_table[b]) / SCALEFACTOR)
-#define COMPUTE_U(r, g, b) \
-  (unsigned char) \
-  ((u_r_table[r] + u_g_table[g] + u_b_table[b]) / SCALEFACTOR + CENTERSAMPLE)
-#define COMPUTE_V(r, g, b) \
-  (unsigned char) \
-  ((v_r_table[r] + v_g_table[g] + v_b_table[b]) / SCALEFACTOR + CENTERSAMPLE)
-
-#define Y_R (SCALEFACTOR *  0.29900)
-#define Y_G (SCALEFACTOR *  0.58700)
-#define Y_B (SCALEFACTOR *  0.11400)
-
-#define U_R (SCALEFACTOR * -0.16874)
-#define U_G (SCALEFACTOR * -0.33126)
-#define U_B (SCALEFACTOR *  0.50000)
-
-#define V_R (SCALEFACTOR *  0.50000)
-#define V_G (SCALEFACTOR * -0.41869)
-#define V_B (SCALEFACTOR * -0.08131)
+    int frame_size;
 
-/*
- * Precalculate all of the YUV tables since it requires fewer than
- * 10 kilobytes to store them.
- */
-static int y_r_table[256];
-static int y_g_table[256];
-static int y_b_table[256];
-
-static int u_r_table[256];
-static int u_g_table[256];
-static int u_b_table[256];
-
-static int v_r_table[256];
-static int v_g_table[256];
-static int v_b_table[256];
+} XanContext;
 
 static int xan_decode_init(AVCodecContext *avctx)
 {
     XanContext *s = avctx->priv_data;
-    int i;
 
     s->avctx = avctx;
+    s->frame_size = 0;
 
     if ((avctx->codec->id == CODEC_ID_XAN_WC3) && 
         (s->avctx->palctrl == NULL)) {
@@ -115,28 +69,14 @@ static int xan_decode_init(AVCodecContext *avctx)
 
     avctx->pix_fmt = PIX_FMT_PAL8;
     avctx->has_b_frames = 0;
-    dsputil_init(&s->dsp, avctx);
-
-    /* initialize the RGB -> YUV tables */
-    for (i = 0; i < 256; i++) {
-        y_r_table[i] = Y_R * i;
-        y_g_table[i] = Y_G * i;
-        y_b_table[i] = Y_B * i;
-
-        u_r_table[i] = U_R * i;
-        u_g_table[i] = U_G * i;
-        u_b_table[i] = U_B * i;
-
-        v_r_table[i] = V_R * i;
-        v_g_table[i] = V_G * i;
-        v_b_table[i] = V_B * i;
-    }
 
     if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
         return -1;
     
-    s->buffer1 = av_malloc(avctx->width * avctx->height);
-    s->buffer2 = av_malloc(avctx->width * avctx->height);
+    s->buffer1_size = avctx->width * avctx->height;
+    s->buffer1 = av_malloc(s->buffer1_size);
+    s->buffer2_size = avctx->width * avctx->height;
+    s->buffer2 = av_malloc(s->buffer2_size);
     if (!s->buffer1 || !s->buffer2)
         return -1;
 
@@ -156,13 +96,15 @@ static inline void bytecopy(unsigned char *dest, unsigned char *src, int count)
         dest[i] = src[i];
 }
 
-static int xan_huffman_decode(unsigned char *dest, unsigned char *src)
+static int xan_huffman_decode(unsigned char *dest, unsigned char *src, 
+    int dest_len)
 {
     unsigned char byte = *src++;
     unsigned char ival = byte + 0x16;
     unsigned char * ptr = src + byte*2;
     unsigned char val = ival;
     int counter = 0;
+    unsigned char *dest_end = dest + dest_len;
 
     unsigned char bits = *ptr++;
 
@@ -173,6 +115,8 @@ static int xan_huffman_decode(unsigned char *dest, unsigned char *src)
             val = src[val - 0x17];
 
         if ( val < 0x16 ) {
+            if (dest + 1 > dest_end)
+                return 0;
             *dest++ = val;
             val = ival;
         }
@@ -186,12 +130,13 @@ static int xan_huffman_decode(unsigned char *dest, unsigned char *src)
     return 0;
 }
 
-static void xan_unpack(unsigned char *dest, unsigned char *src)
+static void xan_unpack(unsigned char *dest, unsigned char *src, int dest_len)
 {
     unsigned char opcode;
     int size;
     int offset;
     int byte1, byte2, byte3;
+    unsigned char *dest_end = dest + dest_len;
 
     for (;;) {
         opcode = *src++;
@@ -201,9 +146,13 @@ static void xan_unpack(unsigned char *dest, unsigned char *src)
             offset = *src++;
 
             size = opcode & 3;
+            if (dest + size > dest_end)
+                return;
             bytecopy(dest, src, size);  dest += size;  src += size;
 
             size = ((opcode & 0x1c) >> 2) + 3;
+            if (dest + size > dest_end)
+                return;
             bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
             dest += size;
 
@@ -213,9 +162,13 @@ static void xan_unpack(unsigned char *dest, unsigned char *src)
             byte2 = *src++;
 
             size = byte1 >> 6;
+            if (dest + size > dest_end)
+                return;
             bytecopy (dest, src, size);  dest += size;  src += size;
 
             size = (opcode & 0x3f) + 4;
+            if (dest + size > dest_end)
+                return;
             bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
             dest += size;
 
@@ -226,9 +179,13 @@ static void xan_unpack(unsigned char *dest, unsigned char *src)
             byte3 = *src++;
 
             size = opcode & 3;
+            if (dest + size > dest_end)
+                return;
             bytecopy (dest, src, size);  dest += size;  src += size;
 
             size = byte3 + 5 + ((opcode & 0xc) << 6);
+            if (dest + size > dest_end)
+                return;
             bytecopy (dest,
                 dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
                 size);
@@ -239,6 +196,8 @@ static void xan_unpack(unsigned char *dest, unsigned char *src)
             if (size > 0x70)
                 break;
 
+            if (dest + size > dest_end)
+                return;
             bytecopy (dest, src, size);  dest += size;  src += size;
         }
     }
@@ -247,105 +206,6 @@ static void xan_unpack(unsigned char *dest, unsigned char *src)
     bytecopy(dest, src, size);  dest += size;  src += size;
 }
 
-static void inline xan_wc3_build_palette(XanContext *s, 
-    unsigned int *palette_data)
-{
-    int i;
-    unsigned char r, g, b;
-    unsigned short *palette16;
-    unsigned int *palette32;
-    unsigned int pal_elem;
-
-    /* transform the palette passed through the palette control structure
-     * into the necessary internal format depending on colorspace */
-
-    switch (s->avctx->pix_fmt) {
-
-    case PIX_FMT_RGB555:
-        palette16 = (unsigned short *)s->palette;
-        for (i = 0; i < PALETTE_COUNT; i++) {
-            pal_elem = palette_data[i];
-            r = (pal_elem >> 16) & 0xff;
-            g = (pal_elem >> 8) & 0xff;
-            b = pal_elem & 0xff;
-            palette16[i] = 
-                ((r >> 3) << 10) |
-                ((g >> 3) <<  5) |
-                ((b >> 3) <<  0);
-        }
-        break;
-
-    case PIX_FMT_RGB565:
-        palette16 = (unsigned short *)s->palette;
-        for (i = 0; i < PALETTE_COUNT; i++) {
-            pal_elem = palette_data[i];
-            r = (pal_elem >> 16) & 0xff;
-            g = (pal_elem >> 8) & 0xff;
-            b = pal_elem & 0xff;
-            palette16[i] = 
-                ((r >> 3) << 11) |
-                ((g >> 2) <<  5) |
-                ((b >> 3) <<  0);
-        }
-        break;
-
-    case PIX_FMT_RGB24:
-        for (i = 0; i < PALETTE_COUNT; i++) {
-            pal_elem = palette_data[i];
-            r = (pal_elem >> 16) & 0xff;
-            g = (pal_elem >> 8) & 0xff;
-            b = pal_elem & 0xff;
-            s->palette[i * 4 + 0] = r;
-            s->palette[i * 4 + 1] = g;
-            s->palette[i * 4 + 2] = b;
-        }
-        break;
-
-    case PIX_FMT_BGR24:
-        for (i = 0; i < PALETTE_COUNT; i++) {
-            pal_elem = palette_data[i];
-            r = (pal_elem >> 16) & 0xff;
-            g = (pal_elem >> 8) & 0xff;
-            b = pal_elem & 0xff;
-            s->palette[i * 4 + 0] = b;
-            s->palette[i * 4 + 1] = g;
-            s->palette[i * 4 + 2] = r;
-        }
-        break;
-
-    case PIX_FMT_PAL8:
-    case PIX_FMT_RGBA32:
-        palette32 = (unsigned int *)s->palette;
-        memcpy (palette32, palette_data, PALETTE_COUNT * sizeof(unsigned int));
-        break;
-
-    case PIX_FMT_YUV444P:
-        for (i = 0; i < PALETTE_COUNT; i++) {
-            pal_elem = palette_data[i];
-            r = (pal_elem >> 16) & 0xff;
-            g = (pal_elem >> 8) & 0xff;
-            b = pal_elem & 0xff;
-            s->palette[i * 4 + 0] = COMPUTE_Y(r, g, b);
-            s->palette[i * 4 + 1] = COMPUTE_U(r, g, b);
-            s->palette[i * 4 + 2] = COMPUTE_V(r, g, b);
-        }
-        break;
-
-    default:
-        av_log(s->avctx, AV_LOG_ERROR, " Xan WC3: Unhandled colorspace\n");
-        break;
-    }
-}
-
-/* advance current_x variable; reset accounting variables if current_x
- * moves beyond width */
-#define ADVANCE_CURRENT_X() \
-    current_x++; \
-    if (current_x >= width) { \
-        index += line_inc; \
-        current_x = 0; \
-    }
-
 static void inline xan_wc3_output_pixel_run(XanContext *s, 
     unsigned char *pixel_buffer, int x, int y, int pixel_count)
 {
@@ -354,124 +214,27 @@ static void inline xan_wc3_output_pixel_run(XanContext *s,
     int index;
     int current_x;
     int width = s->avctx->width;
-    unsigned char pix;
     unsigned char *palette_plane;
-    unsigned char *y_plane;
-    unsigned char *u_plane;
-    unsigned char *v_plane;
-    unsigned char *rgb_plane;
-    unsigned short *rgb16_plane;
-    unsigned short *palette16;
-    unsigned int *rgb32_plane;
-    unsigned int *palette32;
-
-    switch (s->avctx->pix_fmt) {
-
-    case PIX_FMT_PAL8:
-        palette_plane = s->current_frame.data[0];
-        stride = s->current_frame.linesize[0];
-        line_inc = stride - width;
-        index = y * stride + x;
-        current_x = x;
-        while(pixel_count--) {
-
-            /* don't do a memcpy() here; keyframes generally copy an entire
-             * frame of data and the stride needs to be accounted for */
-            palette_plane[index++] = *pixel_buffer++;
-
-            ADVANCE_CURRENT_X();
-        }
-        break;
-
-    case PIX_FMT_RGB555:
-    case PIX_FMT_RGB565:
-        rgb16_plane = (unsigned short *)s->current_frame.data[0];
-        palette16 = (unsigned short *)s->palette;
-        stride = s->current_frame.linesize[0] / 2;
-        line_inc = stride - width;
-        index = y * stride + x;
-        current_x = x;
-        while(pixel_count--) {
 
-            rgb16_plane[index++] = palette16[*pixel_buffer++];
-
-            ADVANCE_CURRENT_X();
-        }
-        break;
-
-    case PIX_FMT_RGB24:
-    case PIX_FMT_BGR24:
-        rgb_plane = s->current_frame.data[0];
-        stride = s->current_frame.linesize[0];
-        line_inc = stride - width * 3;
-        index = y * stride + x * 3;
-        current_x = x;
-        while(pixel_count--) {
-            pix = *pixel_buffer++;
-
-            rgb_plane[index++] = s->palette[pix * 4 + 0];
-            rgb_plane[index++] = s->palette[pix * 4 + 1];
-            rgb_plane[index++] = s->palette[pix * 4 + 2];
-
-            ADVANCE_CURRENT_X();
+    palette_plane = s->current_frame.data[0];
+    stride = s->current_frame.linesize[0];
+    line_inc = stride - width;
+    index = y * stride + x;
+    current_x = x;
+    while((pixel_count--) && (index < s->frame_size)) {
+
+        /* don't do a memcpy() here; keyframes generally copy an entire
+         * frame of data and the stride needs to be accounted for */
+        palette_plane[index++] = *pixel_buffer++;
+
+        current_x++;
+        if (current_x >= width) {
+            index += line_inc;
+            current_x = 0;
         }
-        break;
-
-    case PIX_FMT_RGBA32:
-        rgb32_plane = (unsigned int *)s->current_frame.data[0];
-        palette32 = (unsigned int *)s->palette;
-        stride = s->current_frame.linesize[0] / 4;
-        line_inc = stride - width;
-        index = y * stride + x;
-        current_x = x;
-        while(pixel_count--) {
-
-            rgb32_plane[index++] = palette32[*pixel_buffer++];
-
-            ADVANCE_CURRENT_X();
-        }
-        break;
-
-    case PIX_FMT_YUV444P:
-        y_plane = s->current_frame.data[0];
-        u_plane = s->current_frame.data[1];
-        v_plane = s->current_frame.data[2];
-        stride = s->current_frame.linesize[0];
-        line_inc = stride - width;
-        index = y * stride + x;
-        current_x = x;
-        while(pixel_count--) {
-            pix = *pixel_buffer++;
-
-            y_plane[index] = s->palette[pix * 4 + 0];
-            u_plane[index] = s->palette[pix * 4 + 1];
-            v_plane[index] = s->palette[pix * 4 + 2];
-
-            index++;
-            ADVANCE_CURRENT_X();
-        }
-        break;
-
-    default:
-        av_log(s->avctx, AV_LOG_ERROR, " Xan WC3: Unhandled colorspace\n");
-        break;
     }
 }
 
-#define ADVANCE_CURFRAME_X() \
-    curframe_x++; \
-    if (curframe_x >= width) { \
-        curframe_index += line_inc; \
-        curframe_x = 0; \
-    }
-
-#define ADVANCE_PREVFRAME_X() \
-    prevframe_x++; \
-    if (prevframe_x >= width) { \
-        prevframe_index += line_inc; \
-        prevframe_x = 0; \
-    }
-
 static void inline xan_wc3_copy_pixel_run(XanContext *s, 
     int x, int y, int pixel_count, int motion_x, int motion_y)
 {
@@ -481,123 +244,31 @@ static void inline xan_wc3_copy_pixel_run(XanContext *s,
     int curframe_x, prevframe_x;
     int width = s->avctx->width;
     unsigned char *palette_plane, *prev_palette_plane;
-    unsigned char *y_plane, *u_plane, *v_plane;
-    unsigned char *prev_y_plane, *prev_u_plane, *prev_v_plane;
-    unsigned char *rgb_plane, *prev_rgb_plane;
-    unsigned short *rgb16_plane, *prev_rgb16_plane;
-    unsigned int *rgb32_plane, *prev_rgb32_plane;
-
-    switch (s->avctx->pix_fmt) {
-
-    case PIX_FMT_PAL8:
-        palette_plane = s->current_frame.data[0];
-        prev_palette_plane = s->last_frame.data[0];
-        stride = s->current_frame.linesize[0];
-        line_inc = stride - width;
-        curframe_index = y * stride + x;
-        curframe_x = x;
-        prevframe_index = (y + motion_y) * stride + x + motion_x;
-        prevframe_x = x + motion_x;
-        while(pixel_count--) {
-
-            palette_plane[curframe_index++] = 
-                prev_palette_plane[prevframe_index++];
-
-            ADVANCE_CURFRAME_X();
-            ADVANCE_PREVFRAME_X();
-        }
-        break;
-
-    case PIX_FMT_RGB555:
-    case PIX_FMT_RGB565:
-        rgb16_plane = (unsigned short *)s->current_frame.data[0];
-        prev_rgb16_plane = (unsigned short *)s->last_frame.data[0];
-        stride = s->current_frame.linesize[0] / 2;
-        line_inc = stride - width;
-        curframe_index = y * stride + x;
-        curframe_x = x;
-        prevframe_index = (y + motion_y) * stride + x + motion_x;
-        prevframe_x = x + motion_x;
-        while(pixel_count--) {
-
-            rgb16_plane[curframe_index++] = 
-                prev_rgb16_plane[prevframe_index++];
-
-            ADVANCE_CURFRAME_X();
-            ADVANCE_PREVFRAME_X();
-        }
-        break;
-
-    case PIX_FMT_RGB24:
-    case PIX_FMT_BGR24:
-        rgb_plane = s->current_frame.data[0];
-        prev_rgb_plane = s->last_frame.data[0];
-        stride = s->current_frame.linesize[0];
-        line_inc = stride - width * 3;
-        curframe_index = y * stride + x * 3;
-        curframe_x = x;
-        prevframe_index = (y + motion_y) * stride + 
-            (3 * (x + motion_x));
-        prevframe_x = x + motion_x;
-        while(pixel_count--) {
-
-            rgb_plane[curframe_index++] = prev_rgb_plane[prevframe_index++];
-            rgb_plane[curframe_index++] = prev_rgb_plane[prevframe_index++];
-            rgb_plane[curframe_index++] = prev_rgb_plane[prevframe_index++];
-
-            ADVANCE_CURFRAME_X();
-            ADVANCE_PREVFRAME_X();
-        }
-        break;
-
-    case PIX_FMT_RGBA32:
-        rgb32_plane = (unsigned int *)s->current_frame.data[0];
-        prev_rgb32_plane = (unsigned int *)s->last_frame.data[0];
-        stride = s->current_frame.linesize[0] / 4;
-        line_inc = stride - width;
-        curframe_index = y * stride + x;
-        curframe_x = x;
-        prevframe_index = (y + motion_y) * stride + x + motion_x;
-        prevframe_x = x + motion_x;
-        while(pixel_count--) {
-
-            rgb32_plane[curframe_index++] = 
-                prev_rgb32_plane[prevframe_index++];
-
-            ADVANCE_CURFRAME_X();
-            ADVANCE_PREVFRAME_X();
-        }
-        break;
-
-    case PIX_FMT_YUV444P:
-        y_plane = s->current_frame.data[0];
-        u_plane = s->current_frame.data[1];
-        v_plane = s->current_frame.data[2];
-        prev_y_plane = s->last_frame.data[0];
-        prev_u_plane = s->last_frame.data[1];
-        prev_v_plane = s->last_frame.data[2];
-        stride = s->current_frame.linesize[0];
-        line_inc = stride - width;
-        curframe_index = y * stride + x;
-        curframe_x = x;
-        prevframe_index = (y + motion_y) * stride + x + motion_x;
-        prevframe_x = x + motion_x;
-        while(pixel_count--) {
-
-            y_plane[curframe_index] = prev_y_plane[prevframe_index];
-            u_plane[curframe_index] = prev_u_plane[prevframe_index];
-            v_plane[curframe_index] = prev_v_plane[prevframe_index];
-
-            curframe_index++;
-            ADVANCE_CURFRAME_X();
-            prevframe_index++;
-            ADVANCE_PREVFRAME_X();
+
+    palette_plane = s->current_frame.data[0];
+    prev_palette_plane = s->last_frame.data[0];
+    stride = s->current_frame.linesize[0];
+    line_inc = stride - width;
+    curframe_index = y * stride + x;
+    curframe_x = x;
+    prevframe_index = (y + motion_y) * stride + x + motion_x;
+    prevframe_x = x + motion_x;
+    while((pixel_count--) && (curframe_index < s->frame_size)) {
+
+        palette_plane[curframe_index++] = 
+            prev_palette_plane[prevframe_index++];
+
+        curframe_x++;
+        if (curframe_x >= width) {
+            curframe_index += line_inc;
+            curframe_x = 0;
         }
-        break;
 
-    default:
-        av_log(s->avctx, AV_LOG_ERROR, " Xan WC3: Unhandled colorspace\n");
-        break;
+        prevframe_x++;
+        if (prevframe_x >= width) {
+            prevframe_index += line_inc;
+            prevframe_x = 0;
+        }
     }
 }
 
@@ -613,7 +284,9 @@ static void xan_wc3_decode_frame(XanContext *s) {
     int x, y;
 
     unsigned char *opcode_buffer = s->buffer1;
+    int opcode_buffer_size = s->buffer1_size;
     unsigned char *imagedata_buffer = s->buffer2;
+    int imagedata_buffer_size = s->buffer2_size;
 
     /* pointers to segments inside the compressed chunk */
     unsigned char *huffman_segment;
@@ -626,10 +299,11 @@ static void xan_wc3_decode_frame(XanContext *s) {
     vector_segment =    s->buf + LE_16(&s->buf[4]);
     imagedata_segment = s->buf + LE_16(&s->buf[6]);
 
-    xan_huffman_decode(opcode_buffer, huffman_segment);
+    xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
 
     if (imagedata_segment[0] == 2)
-        xan_unpack(imagedata_buffer, &imagedata_segment[1]);
+        xan_unpack(imagedata_buffer, &imagedata_segment[1], 
+            imagedata_buffer_size);
     else
         imagedata_buffer = &imagedata_segment[1];
 
@@ -727,13 +401,6 @@ static void xan_wc3_decode_frame(XanContext *s) {
             }
         }
     }
-
-    /* for PAL8, make the palette available on the way out */
-    if (s->avctx->pix_fmt == PIX_FMT_PAL8) {
-        memcpy(s->current_frame.data[1], s->palette, PALETTE_COUNT * 4);
-        s->current_frame.palette_has_changed = 1;
-        s->avctx->palctrl->palette_changed = 0;
-    }
 }
 
 static void xan_wc4_decode_frame(XanContext *s) {
@@ -745,16 +412,6 @@ static int xan_decode_frame(AVCodecContext *avctx,
 {
     XanContext *s = avctx->priv_data;
     AVPaletteControl *palette_control = avctx->palctrl;
-    int keyframe = 0;
-
-    if (palette_control->palette_changed) {
-        /* load the new palette and reset the palette control */
-        xan_wc3_build_palette(s, palette_control->palette);
-        /* If pal8 we clear flag when we copy palette */
-        if (s->avctx->pix_fmt != PIX_FMT_PAL8)
-            palette_control->palette_changed = 0;
-        keyframe = 1;
-    }
 
     if (avctx->get_buffer(avctx, &s->current_frame)) {
         av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");
@@ -762,6 +419,14 @@ static int xan_decode_frame(AVCodecContext *avctx,
     }
     s->current_frame.reference = 3;
 
+    if (!s->frame_size)
+        s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
+
+    palette_control->palette_changed = 0;
+    memcpy(s->current_frame.data[1], palette_control->palette, 
+        AVPALETTE_SIZE);
+    s->current_frame.palette_has_changed = 1;
+
     s->buf = buf;
     s->size = buf_size;
 
@@ -789,7 +454,8 @@ static int xan_decode_end(AVCodecContext *avctx)
     XanContext *s = avctx->priv_data;
 
     /* release the last frame */
-    avctx->release_buffer(avctx, &s->last_frame);
+    if (s->last_frame.data[0])
+        avctx->release_buffer(avctx, &s->last_frame);
 
     av_free(s->buffer1);
     av_free(s->buffer2);