avcodec/gsmdec_template: Fix runtime error: signed integer overflow: -22527 * 99113...
[ffmpeg.git] / libavcodec / xan.c
index 1d697c6..4c01c00 100644 (file)
@@ -1,6 +1,6 @@
 /*
  * Wing Commander/Xan Video Decoder
- * Copyright (C) 2003 the ffmpeg project
+ * Copyright (C) 2003 The FFmpeg project
  *
  * This file is part of FFmpeg.
  *
 #include <string.h>
 
 #include "libavutil/intreadwrite.h"
+#include "libavutil/mem.h"
+
+#define BITSTREAM_READER_LE
 #include "avcodec.h"
 #include "bytestream.h"
-#define ALT_BITSTREAM_READER_LE
 #include "get_bits.h"
-// for av_memcpy_backptr
-#include "libavutil/lzo.h"
+#include "internal.h"
 
 #define RUNTIME_GAMMA 0
 
 typedef struct XanContext {
 
     AVCodecContext *avctx;
-    AVFrame last_frame;
-    AVFrame current_frame;
+    AVFrame *last_frame;
 
-    const unsigned char *buf;
+    const uint8_t *buf;
     int size;
 
     /* scratch space */
-    unsigned char *buffer1;
+    uint8_t *buffer1;
     int buffer1_size;
-    unsigned char *buffer2;
+    uint8_t *buffer2;
     int buffer2_size;
 
     unsigned *palettes;
@@ -72,6 +72,19 @@ typedef struct XanContext {
 
 } XanContext;
 
+static av_cold int xan_decode_end(AVCodecContext *avctx)
+{
+    XanContext *s = avctx->priv_data;
+
+    av_frame_free(&s->last_frame);
+
+    av_freep(&s->buffer1);
+    av_freep(&s->buffer2);
+    av_freep(&s->palettes);
+
+    return 0;
+}
+
 static av_cold int xan_decode_init(AVCodecContext *avctx)
 {
     XanContext *s = avctx->priv_data;
@@ -79,7 +92,7 @@ static av_cold int xan_decode_init(AVCodecContext *avctx)
     s->avctx = avctx;
     s->frame_size = 0;
 
-    avctx->pix_fmt = PIX_FMT_PAL8;
+    avctx->pix_fmt = AV_PIX_FMT_PAL8;
 
     s->buffer1_size = avctx->width * avctx->height;
     s->buffer1 = av_malloc(s->buffer1_size);
@@ -92,33 +105,46 @@ static av_cold int xan_decode_init(AVCodecContext *avctx)
         return AVERROR(ENOMEM);
     }
 
+    s->last_frame = av_frame_alloc();
+    if (!s->last_frame) {
+        xan_decode_end(avctx);
+        return AVERROR(ENOMEM);
+    }
+
     return 0;
 }
 
-static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
-    int dest_len)
+static int xan_huffman_decode(uint8_t *dest, int dest_len,
+                              const uint8_t *src, int src_len)
 {
-    unsigned char byte = *src++;
-    unsigned char ival = byte + 0x16;
-    const unsigned char * ptr = src + byte*2;
-    unsigned char val = ival;
-    unsigned char *dest_end = dest + dest_len;
+    uint8_t byte = *src++;
+    uint8_t ival = byte + 0x16;
+    const uint8_t * ptr = src + byte*2;
+    int ptr_len = src_len - 1 - byte*2;
+    uint8_t val = ival;
+    uint8_t *dest_end = dest + dest_len;
+    uint8_t *dest_start = dest;
+    int ret;
     GetBitContext gb;
 
-    init_get_bits(&gb, ptr, 0); // FIXME: no src size available
+    if ((ret = init_get_bits8(&gb, ptr, ptr_len)) < 0)
+        return ret;
 
-    while ( val != 0x16 ) {
-        val = src[val - 0x17 + get_bits1(&gb) * byte];
+    while (val != 0x16) {
+        unsigned idx = val - 0x17 + get_bits1(&gb) * byte;
+        if (idx >= 2 * byte)
+            return AVERROR_INVALIDDATA;
+        val = src[idx];
 
-        if ( val < 0x16 ) {
+        if (val < 0x16) {
             if (dest >= dest_end)
-                return 0;
+                return dest_len;
             *dest++ = val;
             val = ival;
         }
     }
 
-    return 0;
+    return dest - dest_start;
 }
 
 /**
@@ -126,70 +152,76 @@ static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,
  *
  * @param dest destination buffer of dest_len, must be padded with at least 130 bytes
  */
-static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)
+static void xan_unpack(uint8_t *dest, int dest_len,
+                       const uint8_t *src, int src_len)
 {
-    unsigned char opcode;
+    uint8_t opcode;
     int size;
-    unsigned char *dest_end = dest + dest_len;
+    uint8_t *dest_org = dest;
+    uint8_t *dest_end = dest + dest_len;
+    GetByteContext ctx;
 
-    while (dest < dest_end) {
-        opcode = *src++;
+    bytestream2_init(&ctx, src, src_len);
+    while (dest < dest_end && bytestream2_get_bytes_left(&ctx)) {
+        opcode = bytestream2_get_byte(&ctx);
 
         if (opcode < 0xe0) {
             int size2, back;
-            if ( (opcode & 0x80) == 0 ) {
-
+            if ((opcode & 0x80) == 0) {
                 size = opcode & 3;
 
-                back  = ((opcode & 0x60) << 3) + *src++ + 1;
+                back  = ((opcode & 0x60) << 3) + bytestream2_get_byte(&ctx) + 1;
                 size2 = ((opcode & 0x1c) >> 2) + 3;
+            } else if ((opcode & 0x40) == 0) {
+                size = bytestream2_peek_byte(&ctx) >> 6;
 
-            } else if ( (opcode & 0x40) == 0 ) {
-
-                size = *src >> 6;
-
-                back  = (bytestream_get_be16(&src) & 0x3fff) + 1;
+                back  = (bytestream2_get_be16(&ctx) & 0x3fff) + 1;
                 size2 = (opcode & 0x3f) + 4;
-
             } else {
-
                 size = opcode & 3;
 
-                back  = ((opcode & 0x10) << 12) + bytestream_get_be16(&src) + 1;
-                size2 = ((opcode & 0x0c) <<  6) + *src++ + 5;
-                if (size + size2 > dest_end - dest)
-                    return;
+                back  = ((opcode & 0x10) << 12) + bytestream2_get_be16(&ctx) + 1;
+                size2 = ((opcode & 0x0c) <<  6) + bytestream2_get_byte(&ctx) + 5;
             }
-            memcpy(dest, src, size);  dest += size;  src += size;
+
+            if (dest_end - dest < size + size2 ||
+                dest + size - dest_org < back ||
+                bytestream2_get_bytes_left(&ctx) < size)
+                return;
+            bytestream2_get_buffer(&ctx, dest, size);
+            dest += size;
             av_memcpy_backptr(dest, back, size2);
             dest += size2;
         } else {
             int finish = opcode >= 0xfc;
             size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;
 
-            memcpy(dest, src, size);  dest += size;  src += size;
+            if (dest_end - dest < size || bytestream2_get_bytes_left(&ctx) < size)
+                return;
+            bytestream2_get_buffer(&ctx, dest, size);
+            dest += size;
             if (finish)
                 return;
         }
     }
 }
 
-static inline void xan_wc3_output_pixel_run(XanContext *s,
-    const unsigned char *pixel_buffer, int x, int y, int pixel_count)
+static inline void xan_wc3_output_pixel_run(XanContext *s, AVFrame *frame,
+    const uint8_t *pixel_buffer, int x, int y, int pixel_count)
 {
     int stride;
     int line_inc;
     int index;
     int current_x;
     int width = s->avctx->width;
-    unsigned char *palette_plane;
+    uint8_t *palette_plane;
 
-    palette_plane = s->current_frame.data[0];
-    stride = s->current_frame.linesize[0];
+    palette_plane = frame->data[0];
+    stride = frame->linesize[0];
     line_inc = stride - width;
     index = y * stride + x;
     current_x = x;
-    while(pixel_count && (index < s->frame_size)) {
+    while (pixel_count && index < s->frame_size) {
         int count = FFMIN(pixel_count, width - current_x);
         memcpy(palette_plane + index, pixel_buffer, count);
         pixel_count  -= count;
@@ -204,28 +236,46 @@ static inline void xan_wc3_output_pixel_run(XanContext *s,
     }
 }
 
-static inline void xan_wc3_copy_pixel_run(XanContext *s,
-    int x, int y, int pixel_count, int motion_x, int motion_y)
+static inline void xan_wc3_copy_pixel_run(XanContext *s, AVFrame *frame,
+                                          int x, int y,
+                                          int pixel_count, int motion_x,
+                                          int motion_y)
 {
     int stride;
     int line_inc;
     int curframe_index, prevframe_index;
     int curframe_x, prevframe_x;
     int width = s->avctx->width;
-    unsigned char *palette_plane, *prev_palette_plane;
+    uint8_t *palette_plane, *prev_palette_plane;
+
+    if (y + motion_y < 0 || y + motion_y >= s->avctx->height ||
+        x + motion_x < 0 || x + motion_x >= s->avctx->width)
+        return;
 
-    palette_plane = s->current_frame.data[0];
-    prev_palette_plane = s->last_frame.data[0];
-    stride = s->current_frame.linesize[0];
+    palette_plane = frame->data[0];
+    prev_palette_plane = s->last_frame->data[0];
+    if (!prev_palette_plane)
+        prev_palette_plane = palette_plane;
+    stride = 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)) {
-        int count = FFMIN3(pixel_count, width - curframe_x, width - prevframe_x);
 
-        memcpy(palette_plane + curframe_index, prev_palette_plane + prevframe_index, count);
+    if (prev_palette_plane == palette_plane && FFABS(curframe_index - prevframe_index) < pixel_count) {
+         avpriv_request_sample(s->avctx, "Overlapping copy");
+         return ;
+    }
+
+    while (pixel_count &&
+           curframe_index  < s->frame_size &&
+           prevframe_index < s->frame_size) {
+        int count = FFMIN3(pixel_count, width - curframe_x,
+                           width - prevframe_x);
+
+        memcpy(palette_plane + curframe_index,
+               prev_palette_plane + prevframe_index, count);
         pixel_count     -= count;
         curframe_index  += count;
         prevframe_index += count;
@@ -244,42 +294,67 @@ static inline void xan_wc3_copy_pixel_run(XanContext *s,
     }
 }
 
-static void xan_wc3_decode_frame(XanContext *s) {
+static int xan_wc3_decode_frame(XanContext *s, AVFrame *frame)
+{
 
-    int width = s->avctx->width;
+    int width  = s->avctx->width;
     int height = s->avctx->height;
     int total_pixels = width * height;
-    unsigned char opcode;
-    unsigned char flag = 0;
+    uint8_t opcode;
+    uint8_t flag = 0;
     int size = 0;
     int motion_x, motion_y;
-    int x, y;
+    int x, y, ret;
 
-    unsigned char *opcode_buffer = s->buffer1;
+    uint8_t *opcode_buffer = s->buffer1;
+    uint8_t *opcode_buffer_end = s->buffer1 + s->buffer1_size;
     int opcode_buffer_size = s->buffer1_size;
-    const unsigned char *imagedata_buffer = s->buffer2;
+    const uint8_t *imagedata_buffer = s->buffer2;
 
     /* pointers to segments inside the compressed chunk */
-    const unsigned char *huffman_segment;
-    const unsigned char *size_segment;
-    const unsigned char *vector_segment;
-    const unsigned char *imagedata_segment;
-
-    huffman_segment =   s->buf + AV_RL16(&s->buf[0]);
-    size_segment =      s->buf + AV_RL16(&s->buf[2]);
-    vector_segment =    s->buf + AV_RL16(&s->buf[4]);
-    imagedata_segment = s->buf + AV_RL16(&s->buf[6]);
-
-    xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);
-
-    if (imagedata_segment[0] == 2)
-        xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);
-    else
+    const uint8_t *huffman_segment;
+    GetByteContext       size_segment;
+    GetByteContext       vector_segment;
+    const uint8_t *imagedata_segment;
+    int huffman_offset, size_offset, vector_offset, imagedata_offset,
+        imagedata_size;
+
+    if (s->size < 8)
+        return AVERROR_INVALIDDATA;
+
+    huffman_offset    = AV_RL16(&s->buf[0]);
+    size_offset       = AV_RL16(&s->buf[2]);
+    vector_offset     = AV_RL16(&s->buf[4]);
+    imagedata_offset  = AV_RL16(&s->buf[6]);
+
+    if (huffman_offset   >= s->size ||
+        size_offset      >= s->size ||
+        vector_offset    >= s->size ||
+        imagedata_offset >= s->size)
+        return AVERROR_INVALIDDATA;
+
+    huffman_segment   = s->buf + huffman_offset;
+    bytestream2_init(&size_segment,   s->buf + size_offset,   s->size - size_offset);
+    bytestream2_init(&vector_segment, s->buf + vector_offset, s->size - vector_offset);
+    imagedata_segment = s->buf + imagedata_offset;
+
+    if ((ret = xan_huffman_decode(opcode_buffer, opcode_buffer_size,
+                                  huffman_segment, s->size - huffman_offset)) < 0)
+        return AVERROR_INVALIDDATA;
+    opcode_buffer_end = opcode_buffer + ret;
+
+    if (imagedata_segment[0] == 2) {
+        xan_unpack(s->buffer2, s->buffer2_size,
+                   &imagedata_segment[1], s->size - imagedata_offset - 1);
+        imagedata_size = s->buffer2_size;
+    } else {
+        imagedata_size = s->size - imagedata_offset - 1;
         imagedata_buffer = &imagedata_segment[1];
+    }
 
     /* use the decoded data segments to build the frame */
     x = y = 0;
-    while (total_pixels) {
+    while (total_pixels && opcode_buffer < opcode_buffer_end) {
 
         opcode = *opcode_buffer++;
         size = 0;
@@ -313,40 +388,61 @@ static void xan_wc3_decode_frame(XanContext *s) {
 
         case 9:
         case 19:
-            size = *size_segment++;
+            if (bytestream2_get_bytes_left(&size_segment) < 1) {
+                av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
+                return AVERROR_INVALIDDATA;
+            }
+            size = bytestream2_get_byte(&size_segment);
             break;
 
         case 10:
         case 20:
-            size = AV_RB16(&size_segment[0]);
-            size_segment += 2;
+            if (bytestream2_get_bytes_left(&size_segment) < 2) {
+                av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
+                return AVERROR_INVALIDDATA;
+            }
+            size = bytestream2_get_be16(&size_segment);
             break;
 
         case 11:
         case 21:
-            size = AV_RB24(size_segment);
-            size_segment += 3;
+            if (bytestream2_get_bytes_left(&size_segment) < 3) {
+                av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
+                return AVERROR_INVALIDDATA;
+            }
+            size = bytestream2_get_be24(&size_segment);
             break;
         }
 
+        if (size > total_pixels)
+            break;
+
         if (opcode < 12) {
             flag ^= 1;
             if (flag) {
                 /* run of (size) pixels is unchanged from last frame */
-                xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
+                xan_wc3_copy_pixel_run(s, frame, x, y, size, 0, 0);
             } else {
                 /* output a run of pixels from imagedata_buffer */
-                xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
+                if (imagedata_size < size)
+                    break;
+                xan_wc3_output_pixel_run(s, frame, imagedata_buffer, x, y, size);
                 imagedata_buffer += size;
+                imagedata_size -= size;
             }
         } else {
+            uint8_t vector;
+            if (bytestream2_get_bytes_left(&vector_segment) <= 0) {
+                av_log(s->avctx, AV_LOG_ERROR, "vector_segment overread\n");
+                return AVERROR_INVALIDDATA;
+            }
             /* run-based motion compensation from last frame */
-            motion_x = sign_extend(*vector_segment >> 4,  4);
-            motion_y = sign_extend(*vector_segment & 0xF, 4);
-            vector_segment++;
+            vector = bytestream2_get_byte(&vector_segment);
+            motion_x = sign_extend(vector >> 4,  4);
+            motion_y = sign_extend(vector & 0xF, 4);
 
             /* copy a run of pixels from the previous frame */
-            xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
+            xan_wc3_copy_pixel_run(s, frame, x, y, size, motion_x, motion_y);
 
             flag = 0;
         }
@@ -356,9 +452,7 @@ static void xan_wc3_decode_frame(XanContext *s) {
         y += (x + size) / width;
         x  = (x + size) % width;
     }
-}
-
-static void xan_wc4_decode_frame(XanContext *s) {
+    return 0;
 }
 
 #if RUNTIME_GAMMA
@@ -445,148 +539,111 @@ static const uint8_t gamma_lookup[256] = {
 #endif
 
 static int xan_decode_frame(AVCodecContext *avctx,
-                            void *data, int *data_size,
+                            void *data, int *got_frame,
                             AVPacket *avpkt)
 {
+    AVFrame *frame = data;
     const uint8_t *buf = avpkt->data;
     int ret, buf_size = avpkt->size;
     XanContext *s = avctx->priv_data;
-
-    if (avctx->codec->id == CODEC_ID_XAN_WC3) {
-        const uint8_t *buf_end = buf + buf_size;
-        int tag = 0;
-        while (buf_end - buf > 8 && tag != VGA__TAG) {
-            unsigned *tmpptr;
-            uint32_t new_pal;
-            int size;
-            int i;
-            tag  = bytestream_get_le32(&buf);
-            size = bytestream_get_be32(&buf);
-            size = FFMIN(size, buf_end - buf);
-            switch (tag) {
-            case PALT_TAG:
-                if (size < PALETTE_SIZE)
-                    return AVERROR_INVALIDDATA;
-                if (s->palettes_count >= PALETTES_MAX)
-                    return AVERROR_INVALIDDATA;
-                tmpptr = av_realloc(s->palettes, (s->palettes_count + 1) * AVPALETTE_SIZE);
-                if (!tmpptr)
-                    return AVERROR(ENOMEM);
-                s->palettes = tmpptr;
-                tmpptr += s->palettes_count * AVPALETTE_COUNT;
-                for (i = 0; i < PALETTE_COUNT; i++) {
+    GetByteContext ctx;
+    int tag = 0;
+
+    bytestream2_init(&ctx, buf, buf_size);
+    while (bytestream2_get_bytes_left(&ctx) > 8 && tag != VGA__TAG) {
+        unsigned *tmpptr;
+        uint32_t new_pal;
+        int size;
+        int i;
+        tag  = bytestream2_get_le32(&ctx);
+        size = bytestream2_get_be32(&ctx);
+        if (size < 0) {
+            av_log(avctx, AV_LOG_ERROR, "Invalid tag size %d\n", size);
+            return AVERROR_INVALIDDATA;
+        }
+        size = FFMIN(size, bytestream2_get_bytes_left(&ctx));
+        switch (tag) {
+        case PALT_TAG:
+            if (size < PALETTE_SIZE)
+                return AVERROR_INVALIDDATA;
+            if (s->palettes_count >= PALETTES_MAX)
+                return AVERROR_INVALIDDATA;
+            tmpptr = av_realloc_array(s->palettes,
+                                      s->palettes_count + 1, AVPALETTE_SIZE);
+            if (!tmpptr)
+                return AVERROR(ENOMEM);
+            s->palettes = tmpptr;
+            tmpptr += s->palettes_count * AVPALETTE_COUNT;
+            for (i = 0; i < PALETTE_COUNT; i++) {
 #if RUNTIME_GAMMA
-                    int r = gamma_corr(*buf++);
-                    int g = gamma_corr(*buf++);
-                    int b = gamma_corr(*buf++);
+                int r = gamma_corr(bytestream2_get_byteu(&ctx));
+                int g = gamma_corr(bytestream2_get_byteu(&ctx));
+                int b = gamma_corr(bytestream2_get_byteu(&ctx));
 #else
-                    int r = gamma_lookup[*buf++];
-                    int g = gamma_lookup[*buf++];
-                    int b = gamma_lookup[*buf++];
+                int r = gamma_lookup[bytestream2_get_byteu(&ctx)];
+                int g = gamma_lookup[bytestream2_get_byteu(&ctx)];
+                int b = gamma_lookup[bytestream2_get_byteu(&ctx)];
 #endif
-                    *tmpptr++ = (r << 16) | (g << 8) | b;
-                }
-                s->palettes_count++;
-                break;
-            case SHOT_TAG:
-                if (size < 4)
-                    return AVERROR_INVALIDDATA;
-                new_pal = bytestream_get_le32(&buf);
-                if (new_pal < s->palettes_count) {
-                    s->cur_palette = new_pal;
-                } else
-                    av_log(avctx, AV_LOG_ERROR, "Invalid palette selected\n");
-                break;
-            case VGA__TAG:
-                break;
-            default:
-                buf += size;
-                break;
+                *tmpptr++ = (0xFFU << 24) | (r << 16) | (g << 8) | b;
             }
+            s->palettes_count++;
+            break;
+        case SHOT_TAG:
+            if (size < 4)
+                return AVERROR_INVALIDDATA;
+            new_pal = bytestream2_get_le32(&ctx);
+            if (new_pal < s->palettes_count) {
+                s->cur_palette = new_pal;
+            } else
+                av_log(avctx, AV_LOG_ERROR, "Invalid palette selected\n");
+            break;
+        case VGA__TAG:
+            break;
+        default:
+            bytestream2_skip(&ctx, size);
+            break;
         }
-        buf_size = buf_end - buf;
     }
-    if ((ret = avctx->get_buffer(avctx, &s->current_frame))) {
-        av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
-        return ret;
+    buf_size = bytestream2_get_bytes_left(&ctx);
+
+    if (s->palettes_count <= 0) {
+        av_log(s->avctx, AV_LOG_ERROR, "No palette found\n");
+        return AVERROR_INVALIDDATA;
     }
-    s->current_frame.reference = 3;
+
+    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
+        return ret;
 
     if (!s->frame_size)
-        s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
+        s->frame_size = frame->linesize[0] * s->avctx->height;
 
-    if (avctx->codec->id == CODEC_ID_XAN_WC3) {
-        memcpy(s->current_frame.data[1], s->palettes + s->cur_palette * AVPALETTE_COUNT, AVPALETTE_SIZE);
-    } else {
-        AVPaletteControl *palette_control = avctx->palctrl;
-    palette_control->palette_changed = 0;
-    memcpy(s->current_frame.data[1], palette_control->palette,
-           AVPALETTE_SIZE);
-    s->current_frame.palette_has_changed = 1;
-    }
+    memcpy(frame->data[1],
+           s->palettes + s->cur_palette * AVPALETTE_COUNT, AVPALETTE_SIZE);
 
-    s->buf = buf;
+    s->buf = ctx.buffer;
     s->size = buf_size;
 
-    if (avctx->codec->id == CODEC_ID_XAN_WC3)
-        xan_wc3_decode_frame(s);
-    else if (avctx->codec->id == CODEC_ID_XAN_WC4)
-        xan_wc4_decode_frame(s);
-
-    /* release the last frame if it is allocated */
-    if (s->last_frame.data[0])
-        avctx->release_buffer(avctx, &s->last_frame);
+    if (xan_wc3_decode_frame(s, frame) < 0)
+        return AVERROR_INVALIDDATA;
 
-    *data_size = sizeof(AVFrame);
-    *(AVFrame*)data = s->current_frame;
+    av_frame_unref(s->last_frame);
+    if ((ret = av_frame_ref(s->last_frame, frame)) < 0)
+        return ret;
 
-    /* shuffle frames */
-    FFSWAP(AVFrame, s->current_frame, s->last_frame);
+    *got_frame = 1;
 
     /* always report that the buffer was completely consumed */
     return buf_size;
 }
 
-static av_cold int xan_decode_end(AVCodecContext *avctx)
-{
-    XanContext *s = avctx->priv_data;
-
-    /* release the frames */
-    if (s->last_frame.data[0])
-        avctx->release_buffer(avctx, &s->last_frame);
-    if (s->current_frame.data[0])
-        avctx->release_buffer(avctx, &s->current_frame);
-
-    av_freep(&s->buffer1);
-    av_freep(&s->buffer2);
-
-    return 0;
-}
-
-AVCodec xan_wc3_decoder = {
-    "xan_wc3",
-    AVMEDIA_TYPE_VIDEO,
-    CODEC_ID_XAN_WC3,
-    sizeof(XanContext),
-    xan_decode_init,
-    NULL,
-    xan_decode_end,
-    xan_decode_frame,
-    CODEC_CAP_DR1,
-    .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
-};
-
-/*
-AVCodec xan_wc4_decoder = {
-    "xan_wc4",
-    AVMEDIA_TYPE_VIDEO,
-    CODEC_ID_XAN_WC4,
-    sizeof(XanContext),
-    xan_decode_init,
-    NULL,
-    xan_decode_end,
-    xan_decode_frame,
-    CODEC_CAP_DR1,
-    .long_name = NULL_IF_CONFIG_SMALL("Wing Commander IV / Xxan"),
+AVCodec ff_xan_wc3_decoder = {
+    .name           = "xan_wc3",
+    .long_name      = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_XAN_WC3,
+    .priv_data_size = sizeof(XanContext),
+    .init           = xan_decode_init,
+    .close          = xan_decode_end,
+    .decode         = xan_decode_frame,
+    .capabilities   = AV_CODEC_CAP_DR1,
 };
-*/